PRIMERAS JORNADAS JÓVENES ICMUV

El 23 de Junio a las 12h presentamos algunas de las actividades del Instituto

en un piscolabis científico con 22 pósters

Aquí puedes encontrar los abstracts

¡El ICMUV rejuvenece! ¿Sabes quén es quién?

 

PRIMERAS JORNADAS JÓVENES ICMUV 1

- Multifunctional polymer/metal oxide hybrid nanoparticles by miniemulsion polymerization Olaia Álvarez Bermúdez, Katharina Landfester, Rafael Muñoz Espí

2

- Stability of gallium selenide nanoflakes: effects on their morphological and optical properties Daniel Andres Penares, Mauro Brotons Gisbert, Ana Cros, Juan P. Martínez Pastor, Juan F. Sánchez-Royo

3

- Morphological manipulation of the luminescent response of atomically thin Indium Selenide

nanosheets Mauro Brotons Gisbert Mauro BrotonsGisbert, Daniel Andres Penares, Rafael Abargues, Pedro J. Rodríguez

Ana Cros, Alfredo Segura, Juan P. Martínez Pastor, Juan F. Sánchez Royo

4

- Waveguide acousto-optical modulators for integrated photonics Dominik Bühler, Antonio Crespo Poveda, Andrés Cantarero, Mauricio Morais de Lima

5

- A passively mode locked high peak power all fiber laser Antonio Alejandro Carrascosa Rubio, José L. Cruz, Antonio Díez, Miguel V. Andrés

6

- Conducting polymers and hybrid materials for thermoelectric applications

Mario Culebras Rubio

7

- Synthesis of Nanowires by the hard template method and its applications Antonio García Barberá

8

- Use of Static Magnetic Fields for Multipactor Mitigation in Coaxial Transmission Lines Daniel González Iglesias, Benito Gimeno Martínez, Rafael Mata Sanz

9

- Multipactor RF Breakdown Analysis in a Parallel-plate Waveguide partially filled with a

Magnetized Ferrite Daniel González Iglesias, Benito Gimeno Martínez, Rafael Mata Sanz

i

10

- Microscopio de fuerzas atómicas: Un bastón para el mundo nanométrico Daniel Martínez Cercós, Eleonora Secco

11

- El ESA/VSC Laboratorio Europeo de Materiales de Alta Potencia para el Espacio. Consorcio

Espacial Valenciano Rafael Mata Sanz, Daniel Sánchez Iglésias, Benito Gimeno Martínez

12

- Fabrication of solution processed QD-solids by doctor blading technique and their application for

photodetection Alberto Maulu, P. J. Rodríguez Cantó, Rafael Abargues, Juan P. Martínez Pastor

13

- Generalized plane piezoelectric problem: Application to Heterostructure Nanowires Heruy Mengistu, Alberto García Cristobal

14

- High-performance PbS colloidal quantum dot photodetectors operating at telecommunications

wavelengths.

Juan Navarro Arenas, P. J. Rodríguez Cantó, A. Maulu, I. Suarez, R. Abargues, J. P. Martínez Pastor

15

- High-Q-one and two-dimensional phononic cavities André Oliveira Bilobran, M. M. de Lima Jr., A. Cantarero, P. V. Santos

16

- Demonstration of a fractional differentiator based on long period gratings in fiber optics Luis Poveda Wong, Antonio Carrascosa, Christian Cuadrado Laborde, José Luis Cruz, Antonio Díez, Miguel Vicente

Andrés

17

- UV-patternable nanocomposite containing CdSe and PbS quantum dots as miniaturized

luminescent chemo-sensors Pedro J. Rodríguez Cantó

18

- Porous core-shell nanoparticles for biomedical applications Soledad Roig Sánchez, Jamal El Haskouri, Pedro Amorós

19

- Characterization of Middle Paleolithic flint from the “Abrigo de la Quebrada” site (Chelva,

Valencia, Spain) by spectroscopic techniques Clodoaldo Rodán García, Jorgelina Carballo, Sonia Murcia, Aleix Eixea, Valentín Villaverde, João Zilhão

20

- Surface waves resonances of a standard optical fiber: Characterization of the elasto-optic effect. Xavier Roselló Mechó, M. Delgado Pinar, A. Díez, M. V. Andrés

ii

21

- Tunable Raman scattering in Au nanorods decorated ZnO nanowire hybrid structures E. Secco, A. Pescaglini, D. Cammi, C. Ronning, Nuria Garro , D. Iacopino

22

- Concentration and redirection of light in in metal nanoparticle/polymer nanocomposites

waveguides Mattia Signoretto. I. Suárez, R. Abargues, P. Rodríguez Cantó, V. Chirvony, J. Martínez-Pastor

iii

Multifunctional polymer/metal oxide hybrid nanoparticles by miniemulsion polymerization

Olaia Álvarez Bermúdez*1,2, Katharina Landfester2, Rafael Muñoz-Espí1 1) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedràtic José

Beltrán 2, 46980 Paterna, Valencia, Spain2) Max Planck Institute for Polymer Research, Mainz, Germany

*E-mail: olaia.alvarez@uv.es

The latest trends in materials science are addressed towards the design of complex polymer–inorganic hybrid materials. The integration of different inorganic functionalities with the stability, biocompatibility or processability features of polymers allows the generation of multifunctional nanoparticles [1]. In this context, colloidal strategies offer a “green” and versatile pathway for synthesizing nanostructured systems [2]. Morphology plays an essential role in the final properties of hybrid materials and its relevance increases with the complexity of the system. However, the establishment of a precise structural control remains a challenging task, hindered by the different polarity of the polymer and the inorganic components. This work is focused on the development of colloidal nanoparticles that comprise two different metal oxides in the same polymer particle: magnetite in the inner part and a second catalytically active oxide on the surface, prepared either ex situ prior polymerization or crystallized in situ. To overcome structural limitations, miniemulsion polymerization has been selected as a synthetic route. Structure of hybrid colloidal systems is mostly governed by self-assembly processes driven by a minimization of the overall interfacial energy that we address by chemical modification of the surface of the inorganic components with alkoxysilanes. Silane chemistry offers a broad spectrum of accessible functional groups and chain lengths that will affect in a different manner the migration of metal oxide nanoparticles during the in-situ polymerization, so that the final location of the functional inorganic component can be controlled [3, 4]. The metal oxide nanoparticles are hydrophobized by silanization for compatibilization with the monomer, which is polymerized afterwards by free-radical miniemulsion polymerization. In summary, we develop magnetically separable hybrid systems with applicability in catalysis, aiming a control of the migration of the inorganic components within polymer by specific surface functionalization.

[1] Fischer, V., Bannwarth, M. B., Jakob, G., Landfester, K., Muñoz-Espí, R., Journal of Physical Chemistry C 117, 5999–6005, 2013. [2] M. A. Hood, M. Mari, R. Muñoz-Espí. Materials 2014, 7, 4057–4087. [3] A. Schoth, C. Wagner, L. L. Hecht, S. Winzen, R. Muñoz-Espí, H. P. Schuchman, K. Landfester, Colloid. Polym. Sci. 2014, 292, 2427–2437. [4] A. Schoth, A. D. Keith, K. Landfester, R. Muñoz-Espí, RSC Adv. 2016, DOI: 10.1039/c6ra08896a

1

Stability of gallium selenide nanoflakes: effects on their morphological

and optical properties

Daniel Andres-Penares1, Mauro Brotons-Gisbert

1, Ana Cros

1, Juan P. Martínez-Pastor

1,

Juan F. Sánchez-Royo1

1) Materials Science Institute (ICMUV), University of Valencia, C/ Catedrático José

Beltrán 2, 46980 Paterna, Valencia, Spain

*E-mail: lowdim@uv.es

In the last years, two-dimensional materials have achieved the scientific community

attention since the first graphene exfoliation [1], due to their outstanding and

unexpected new properties. In particular, 2D layered semiconductors have been studied

looking for their implementation in new optoelectronic devices. Is in this context,

gallium selenide (GaSe), an indirect III-VI layered semiconductor with a 2.02 eV band

gap at room temperature [2], has a huge interest due to its applications in

optoelectronics and its complementarity with other layered semiconductors with a lower

band gap. It is remarkable that GaSe has an absortion edge near 620 nm which shifts to

higher energies as long as the number of layers is reduced, arriving to the UV in the

monolayer [3]. Nevertheless, the low stability of GaSe in air hampers its promising

applications.

In the present work, we study the stability of GaSe nanoflakes in ambient conditions by

photoluminescence (PL) and atomic force microscopy (AFM). AFM characterization

reveals deep changes in sample morphology due to sample oxidation. The band gap of

GaSe nanoflakes, as revealed by PL measurements, increases as the sample thickness

decreases. However, sample stability deeply alters luminescent response of the

nanoflakes. Discussion is oriented to prevent or struggle this problem.

Figure 1. On the left, GaSe flake optical image. On the right, photoluminescence spectra

measured in the points marked in the image

[1] Electric Field Effect in Atomically Thin Carbon Films; Novoselov, K. S.; Geim, A.

K.; Morozov, S. V.; Jiang, D.; Zhang, Y.; Dubonos, S. V.; Grigorieva, I. V.; Firsov, A.

A. Science 2004, 306 (5696), 666−669.

[2] Light-induced transmission nonlinearities in gallium selenide ; Ch. Ferrer-Roca, J.

Bouvier, A. Segura, M. V. Andres, and V.Munoz. J. Appl. Phys., 85, 666–669, (1999).

[3] Size-induced effects in gallium selenide electronic structure: The influence of

interlayer interactions; D. V. Rybkovskiy. Phys. Rev. B, 84, 085314, (2011).

2

Morphological manipulation of the luminescent response of atomically thin

Indium Selenide nanosheets

Mauro Brotons-Gisbert, Daniel Andres-Penares, Rafael Abargues, Pedro J. Rodríguez-Canto,

Ana Cros, Alfredo Segura, Juan P. Martínez-Pastor, Juan F. Sánchez-Royo

Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José

Beltrán 2, 46980 Paterna, Valencia, Spain

*E-mail: lowdim@uv.es

Many efforts have been devoted to manipulate the morphology of two-dimensional (2D)

materials to tune and improve their functionalities. Single layers (SLs) of transition-metal

dichalcogenides offer unquestionable technological applications [1-3]. Nevertheless, tuning

their properties for optoelectronic applications is challenging due to the intrinsically localized

nature and orbital character of the d-states that dominate their valence and conduction bands.

2D forms of other layered semiconductors, as Indium Selenide, are less explored and may

exhibit interesting and tunable properties [4,5]. First-principles calculations predicted that 2D

InSe should produce a band-gap tuning window as large as 1.1 eV [4]. Also, devices based on

few-layer InSe have shown promising applications [6,7]. In this communication, we show the

ability of nanotexturing strategies to enhance the luminescent response of atomically thin

Indium Selenide nanosheets. Besides, quantum-size effects make this two-dimensional

semiconductor to exhibit one of the largest band gap tunability ranges observed in a

two-dimensional semiconductor: from 1.25 eV, in bulk, to 2.1 eV, in the single layer. These

results are relevant for the design of new optoelectronic devices, including heterostructures of

two-dimensional materials with optimized band gap functionalities and in-plane

heterojunctions with minimal junction defect density.

Figure 1: (Left) Experimental scheme and

demosntration of the nanotexturing strategy

to enhance the luminescent response of 2D

InSe. (Right) InSe photoluminescence for

nanosheets with different thicknesses.

[1] A. Splendiani et al., Nano Lett., 10 (2010) 1271-1275.

[2] B. Radisavljevic et al., Nature Nanotech., 6 (2011) 147-150.

[3] Y. J. Zhang et al., Science, 344 (2014) 725-728.

[4] J. F. Sánchez-Royo et al., Nano Res., 7 (2014) 1556-1568.

[5] G. W. Mudd et al., Adv. Mater., 25, (2013) 5714-5718.

[6] W. Feng et al., Adv. Mater., 26 (2014) 6587-6593.

[7] W. Luo et al., Adv. Opt. Mater., 3 (2015) 1418-1423.

3

Waveguide acousto-optical modulators for

integrated photonics

D. D. Bühler, A. Crespo-Poveda, A. Cantarero and M. M. de Lima, Jr.

Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José Beltrán 2, 46980 Paterna, Valencia, Spain

E-mail:dominik.buhler@uv.es

We investigate designs for an acoustically tuneable arrayed waveguide system for

the application in integrated photonics. We will explore novel concepts beyond

recently demonstrated devices based on an array of ridge single-mode waveguides

(WG) tuned by a standing surface acoustic wave (SAW) [1]. The SAW is induced by

two interdigital transducers that are placed opposite of each other in such a way that

its propagation direction coincides perpendicularly with the WGs and enables us to

alter the refractive index of each arm discretely. The WGs connect two multimode

interference (MMI) couplers of distinct lengths that are employed as power splitters

and combiners, respectively. In this manner, light entering one of the first MMI’s

channel can be dynamically modulated to exit at a specific output channel of the

second MMI.

As a first step, we redesigned the devices through detailed simulations for operation

at the telecommunication wavelengths around 1.55 µm, working on a (Al,Ga)As

platform and tuned by a SAW in the low GHz frequency. After careful optimization,

the system will be fabricated and subsequently experimentally characterized. Further

tasks include the adaption of the modulator to an InP platform, taking advantage of

integrated light sources and opening the way for even more compact device

structures.

[1] A. Crespo-Poveda et al. Optics Express 23, 21213 (2015)

4

A Passively Mode-Locked High Peak Power all Fiber Laser

Antonio Carrascosa*, José L. Cruz, Antonio Díez and Miguel V. Andrés

Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José Beltrán 2, 46980 Paterna, Valencia, Spain

*E-mail: antonio.carrascosa@uv.es

Mode-Locked Laser can generate short pulses (femtosecond to picosecond), an essential characteristic that makes the laser suitable for many applications such as material processing [1], CARS microscopy, fluorescence lifetime imaging measurements, high-resolution LIDAR systems [2, 3] and supercontinuum source [4].

We are developing a passively mode-locked fiber laser where all components used are made in optical fiber. This set up is more compact and robust than lasers built on free space allowing an increase in stability and beam quality. The active medium is an ytterbium doped fiber and the laser modulation is generated by a saturable absorbed. The laser is able to work at different repetition rate and power is adjustable. Figure 1 shows the laser set up where there are 3 parts. 1st the Oscillator, 2nd pre-Amplifier and frequency rate selector and 3rd the Amplifier. Figure 2 shows the laser pulse train stability.

The laser power is tunable reaching an average maximum power of 6W @ 20MHz, 4.3W @ 2MHz, 3.88W @1MHz and 3.47W @750KHz and maximum peak power of 13KW @ 20MHz, 106KW @ 2MHz, 194W @1MHz and 220KW @750KHz. Figure 3 shows the laser peak power as function of pump power.

Figure 3: Laser peak power as function of pump power

[1] Rafael R. Gattass & Eric Mazur. Femtosecond laser micromachining in transparent materials. Nature Photonics 2, 219 - 225 (2008)

[2] Baumgartl M, Gottschall T, Abreu-Afonso J, Díez A, Meyer T, Dietzek B, Rothhardt M, Popp J, Limpert J, Tünnermann A. Alignment-free, all-spliced fiber laser source for CARS microscopy based on four-wave-mixing. Opt Express 20 (19). 2012

[3] Xiaolong Tian, Ming Tang, Perry Ping Shum, Yandong Gong, Chinlon Lin, Songnian Fu, and Taishi Zhang. High-energy laser pulse with a submegahertz repetition rate from a passively mode-locked fiber laser. Opt Letters Vol. 34, No. 9. 2009

[4] S. Kivistö, R. Herda, and O. G. Okhotnikov. All-fiber supercontinuum source based on a mode-locked ytterbium laser with dispersion compensation by linearly chirped Bragg grating. Opt Express, Vol. 16, No. 1. 2008

5

Conducting polymers and hybrid materials for thermoelectric applications

Mario Culebras1

1) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José Beltrán 2,

46980 Paterna, Valencia, Spain

*E-mail: mario.culebras@uv.es

More than two thirds parts of the energy that is produced is lost as heat losses. In

consideration of that, it is crucial to find effective ways to recover all this loss energy. The use

of thermoelectric materials makes possible to recover all this energy due to the Seebeck effect.

In the last few years, several intrinsically conducting polymers (ICPs) have been successfully

used in the field of thermoelectricity. The dimensionless figure of merit ZT (ZT=S2σT/κ)

where S, σ and κ are the Seebeck coefficient, the electrical and thermal conductivities,

respectively, has been improved several orders of magnitude, until values very close to those

of inorganic materials. Polymers show, in addition, many advantages over inorganic materials,

such as: non scarcity of raw materials, lack of toxicity, lower cost of production and many

others. In this work, the focus is to provide several routes to increase the thermoelectric

efficiency of conducting polymers such as: chemical and electrochemical de/doping or the

incorporation of nanofillers to the polymer matrix. Using these methods it is possible to

achieve a ZT > 0.2 for ICPs[1, 2]. In addition, a new method for the fabrication of

thermoelectric modules (TEG) has been developed using only one type of ICP. As a proof of

concept, we have developed a thermal sensor based on poly(3,4 ethylenedioxythiophene)

(PEDOT) nanofilms as thermoelectric material.

Figure 1: Scheme of

thermoelectric generator.

[1] M. Culebras, C. Gómez, A. Cantarero, Review on Polymers for Thermoelectric Applications,

Materials 7 (2014) 6701-6732.

[2] M. Culebras, B. Uriol, C.M. Gomez, A. Cantarero, Controlling the thermoelectric properties of

polymers: application to PEDOT and polypyrrole, Phys Chem Chem Phys 17 (2015) 15140-15145.

6

Synthesis of Nanowires by the hard template method and its applications

Antonio García-Barberá1

1) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José

Beltrán 2, 46980 Paterna, Valencia, Spain

*E-mail: antonio.garcia-barbera@uv.es

Nanostructured materials have become an important field in Science. This is a

multidisciplinary branch where many others can converge: Biology, Physics, Chemistry,

Material Science and so on. Nanotechnology [1] has allowed to pass from the mesoscopic to

the nanoscopic scale. With the reduction of the materials lengths new phenomena have been

achieved, which cannot be described by the classical physics because it belongs to the quantic

regime.

In order to achieve architectures at the nanoscale several strategies are available [2].

Each of them presents a series of own techniques for systems depending on the structure to be

made. One of these possibilities is the structuration that employs pre-structured environments.

This environment is known as template [3]. Within them, they can be differentiated between:

soft (dynamic structure) and hard (static structure) environments.

Regarding to hard templates, several metal oxides are commonly used, but the

aluminium oxide system (alumina, Al2O3) is the most extended [4]. This oxide presents a

nanoporous arrangement that can be obtained by controlling the oxidation conditions of the

aluminium metal. This porous oxide can be used as hard template to growth organic and

metallic nanowires by electrochemical reaction. The nanowires generated by this process

present a huge quality and homogeneity, being able to apply on such diverse topics as the

nature of them.

Figure 1: Evolution of the nanostructuration process: template (left) and nanowires (right).

[1] Nalwa, H. S., ed Handbook of nanostructured Materials and Nanotechnology, Academic Press: New York (2000).

[2] Rodgers, P., Nanofabrication: top down, bottom up, Nature Technology, 87: 10.1038 (2006).

[3] Stein, A., Rudisill, S.G. and Petkovic N. D., Perspective on the influence of interactions between hard and soft templates

and precursors on morphology of hierarchically structures porous materials, Chemistry Materials, 26: pag. 259-276 (2014).

[4] X.Y. Han, W.Z. Shen, Improved two-step anodization technique for ordered porous anodic aluminum membranes,

Journal of Electroanalytical Chemistry, 655: pag. 56-64 (2011)

7

Use of Static Magnetic Fields for Multipactor Mitigation in Coaxial

Transmission Lines

Daniel González-Iglesias1, Benito Gimeno Martínez

1, Rafael Mata Sanz

1

1)Dpto. de Física Aplicada y Electromagnetismo, Instituto de Ciencia de Materiales (ICMUV),

Consorcio Espacial Valenciano, Paterna, Valencia, Spain

*E-mail: Daniel.gonzalez-iglesias@uv.es, Benito.gimeno@uv.es, Rafael.mata@uv.es

The main aim of this work is the analysis of the mitigation of a multipactor discharge [1]

existing within a coaxial waveguide structure by means of the use of a DC magnetic field. In a

first step, multipactor numerical simulations were performed assuming that the coaxial

waveguide was immersed in an axial DC homogenous magnetic field. To reach this goal, we

developed in-house a multipactor simulation code based on the effective electron model.

Numerical simulations show the capability of an axial DC homogeneous magnetic field to

prevent the discharge, whenever the strength of the applied magnetic field is over an onset

that depends on the specific RF frequency. Then, a long solenoid was designed and

manufactured to implement a DC homogeneous magnetic field over a coaxial sample, which

was inserted within. An experimental test campaign was carried out to confirm the theoretical

predictions, finding good agreement between both of them. In a second stage, we explored the

feasibility of using permanent magnets to achieve the multipactor mitigation. First, the

magnetic field of a permanent magnet was numerically computed in order to perform

multipactor simulations. Preliminary theoretical results support the feasibility of multipactor

mitigation for a certain frequency range of the RF signal. Due to that, a neodymium

permanent was designed and manufactured in order to carry out a second test campaign.

Experimental results are in agreement with theory and multipactor mitigation was found when

using permanent magnets.

[1] J. Vaughan, “Multipactor,” IEEE Trans. Electron Devices, vol. 35, no. 7, pp.

1172–1180, Jul. 1988.

8

Multipactor RF Breakdown Analysis in a Parallel-plate Waveguide partially

filled with a Magnetized Ferrite

Daniel González-Iglesias1, Benito Gimeno Martínez

1, Rafael Mata Sanz

1

1)Dpto. de Física Aplicada y Electromagnetismo, Instituto de Ciencia de Materiales (ICMUV),

Consorcio Espacial Valenciano, Paterna, Valencia, Spain

*E-mail: Daniel.gonzalez-iglesias@uv.es, Benito.gimeno@uv.es, Rafael.mata@uv.es

The purpose of this work is the analysis of the multipactor effect [1] in a parallel-plate

waveguide with a ferrite slab magnetized by means of a static magnetic field. To reach this

aim, we developed in-house a multipactor simulation code based on the Monte-Carlo method

to compute the multipactor RF voltage threshold. The software code, based on the effective

electron model, allows the 3D tracking of the individual trajectories of a set of effective

electrons. The current simulation model includes the space charge effect, that takes into

account the coulombian interaction among electrons by means of a single electron sheet

model, as well as the dielectric polarization effect of the ferrite that leads to the presence of a

DC electric field. Multipactor susceptibility chart for a ferrite loaded waveguide assuming

several values of the ferrite magnetization field is presented. Effective electron trajectories at

some interesting points of the curves are depicted for a better understanding of the breakdown

phenomenon, finding double-surface and single-surface multipactor regimes.

[1] J. Vaughan, “Multipactor,” IEEE Trans. Electron Devices, vol. 35, no. 7, pp.

1172–1180, Jul. 1988.

9

Microscopio de fuerzas atómicas: Un bastón para el mundo

nanométrico Daniel Martínez Cercós1 & Eleonora Secco1

1) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José Beltrán 2, 46980 Paterna, Valencia, Spain

*E-mail: marcerda@alumni.uv.eseleonora.secco@uv.es

“En el año 2000, cuando se mire hacia atrás, todo el mundo se preguntará por qué hasta el año 1960 nadie empezó a moverse seriamente en esta dirección”.

Éstas eran las palabras de Richard Feynman (Nobel de física en 1965) en el año 1959 durante una conferencia en el Instituto de Tecnología de California en Pasadena que trató sobre cómo manipular, controlar y fabricar objetos de muy pequeñas dimensiones. Podríamos decir que este fue el inicio teórico de lo hoy conocido como nanotecnología. Sin embargo, en la época no se disponía de las herramientas necesarias para este propósito. Ya en 1982, cuando Gerd Binnig y Heinrich Rohrer inventaron el microscopio de efecto túnel (STM), se comenzó a dotar de ojos y manos a la nanotecnología. Los microscopios de campo cercano, como el STM, constituyen una familia de instrumentos que permiten estudiar la superficie y manipular diversos materiales en una escala comprendida entre la micra (1000 nm) y las distancias atómicas (0.1 nm). El problema del STM es que está limitado al estudio de materiales conductores, limitación que quedó resuelta en 1986 con el desarrollo del Microscopio de Fuerzas Atómicas (Atomic Force Microscope, AFM) por Binnig, Quate y Gerber. Desde ese momento, se ha hecho posible la manipulación y el estudio de materiales, estructuras, dispositivos y sistemas funcionales a través del control y ensamblado de la materia a la escala del nanómetro abriéndose así un camino real en la nanociencia y la nanotecnología, mostrándonos un nuevo mundo lleno de posibilidades y materializando las palabras que, ya en 1959, se atrevió decir Feynman.

En este trabajo presentaremos una descripción básica del AFM y algunos resultados obtenidos mediante esta técnica y otras relacionadas con ella (Kelvin Probe Force Microscopy, KPFM).

[1] E. Meyer, H. J. Hug y R. Bennewitz. Scanning Probe Microscopy. The Lab on a Tip.

(Springer, Berlin, 2004)

[2] Peter Milde. (2011). Visualization of local charge densities with Kelvin Probe Force

Microscopy. Technische Universität Dresden.

[3] Fundación Española para la Ciencia y la Tecnología, FECYT. (2009). Nanociencia y

nanotecnología. Entre la ciencia ficción del presente y la tecnología del futuro.

Extraído de: http://www.fecyt.es/es/publicacion/unidad-didactica-nanociencia-y-

nanotecnologia-entre-la-ciencia-ficcion-del-presente-y-la

10

El ESA/VSC Laboratorio Europeo de Materiales de Alta Potencia para el

Espacio. Consorcio Espacial Valenciano

Rafael Mata Sanz1,*

, Daniel Sánchez Iglésias2, Benito Gimeno Martínez

1

1) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José Beltrán 2, 46980 Paterna,

Valencia, Spain

2) Val Space Consortium, ESA-VSC High Power Space Materials Laboratory, Escuela Técnica Superior de Ingeniería,

University of Valencia, Avenida de la Universidad s/n, 46100 Burjassot, Valencia, Spain.

*E-mail: rafael.mata@uv.es

Hoy en día, los satélites participan activamente en la vida social, tecnológica y científica. Todos los días la

humanidad hace uso de ellos, como por ejemplo: en meteorología, comunicaciones o sistemas de posicionamiento.

Para que todo esto sea posible, es necesario un control del tráfico de información mediante ondas de comunicación

entre los satélites y la tierra. Pero, las ondas que transportan esta información pueden interaccionar de forma

nociva con los propios componentes que conforman el satélite. En el ESA/VSC Laboratorio Europeo de

Materiales de Alta Potencia para Espacio [1] se investigan los diferentes procesos relacionados con la interacción

entre las ondas y los materiales que componen los distintos dispositivos instalados en los satélites. Entre los cuales

podemos destacar a continuación.

Cuando los satélites son lanzados a la órbita que les corresponde, es necesario que todo el aire que queda atrapado

en su interior se libere antes de ser encendidos. Este proceso se conoce como venteo y/o desgasificado de un

componente. Algunos componentes utilizados en el mundo de las comunicaciones requieren estar fabricados en un

determinado material. No obstante, hay muchos factores a tener en cuenta, como por ejemplo, la necesidad de que

el material sea ligero, y además, buen conductor. Por este motivo, en ocasiones un componente puede estar

fabricado en un determinado material aislante de baja densidad, pero, debe de estar recubierto por una fina capa de

metal que mejore su respuesta eléctrica. Para ello se realizan recubrimientos de metales sobre superficies.

Finalmente, los electrones de los vientos solares o de los propios componentes del satélite pueden interaccionar

con el campo electromagnético de las ondas y ser acelerado hacia las paredes del material. Dependiendo de la

velocidad con la que colisionen, pueden suceder varios procesos. El primero es que pueden rebotar en la superficie

y retroceder como si de una pelota de tenis se tratase. Por otra parte, pueden ser absorbidos y, mediante colisiones

con los átomos, ceder su energía a los demás electrones del material, pudiendo así, ser arrancados. Estos últimos

producen al Emisión Secundaria de Electrones (SEY) y pueden ser acelerados nuevamente por la onda

electromagnética de comunicación; y así sucesivamente pudiendo provocar la destrucción del dispositivo. La SEY

depende fuertemente de parámetros superficiales y de la temperatura [2] y el VSC se analizan todas esta

propiedades de los materiales que puedan afectar a las telecomunicaciones entre los satélites y la tierra.

[1] http://www.val-space.com/

[2] R. Mata, M. A. Cuenca, B. Gimeno, V. E. Boria, D. Ramirez, E. Sanchis, and D. Raboso, “Roughness control of silver

growth by means of EBPVD and its influence on secondary emission yield parameters as a function of temperature,” in

Proceedings of 8th International Workshop on Multipactor, Corona and Passive Intermodulation in Space RF Hardware,

Valencia, Spain, 17-19 September 2014.

11

Fabrication of solution-processed QD-solids by doctor blading technique and

their application for photodetection

1) Maulu*,1, P. J. Rodríguez-Cantó1, I. Suarez1, R. Abargues2, J. P. Martínez-Pastor1

1) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José Beltrán 2,

46980 Paterna, Valencia, Spain

2) Intenanomat S.L. C/Catedrático José Beltrán 2, 46980 Paterna, Spain

*E-mail: maulu@uv.es

Colloidal quantum dots (CQDs) are increasingly gaining much attention in the photonic

community as active material for optical and optoelectronic applications [1]. The reason of

that comes from the extraordinary optical properties of QDs that arise from the quantum

confinement of excitons when the size of the nanocrystals lies below the exciton bohr radius.

Therefore, the control of the QD radius allows the absorption and emission wavelength of

light to be tuned [2]. CQDs are typically synthesized using hot injection techniques that

provide high-quality QDs capped with organic molecules. Hence, the solution-processibility

make them adequate candidates for the development of QD-solids, which can be considered

one of the more advanced concepts for photodetection [3].

In this work, we focused our research on the synthesis and characterization of IR CQDs (PbS,

PbSe, and lead-free QDs) and the development of QD-solids to approach photodetection in

the IR regime (900 – 1700 nm). The colloidal QDs are deposited onto the substrate by doctor

blading technique to form layers with thicknesses of 300 – 800 nm. This coating technique is

an attractive alternative to conventional spin coating since it is capable of achieving great

thicknesses consuming far less material and less processing time than the conventional

spin-coating. To enhance the electronic transport and successfully passivate surface defects in

the CQD films we carry out different ligand exchange strategies using organic ligands and

monovalent halide anions. Moreover, optical characterization of the resulting layers will be

discussed in detail.

For the fabrication of the photodetector, we have considered two different designs based on

the QD-solid concept: CQDs deposited on a nano/micro-gap area between the metal contacts

or a Schottky-heterostructure design. The optoelectronic characteristics of both device

architectures will be investigated and presented in detail.

[1] G. Konstantatos and E. Sargent. Colloidal Quantum Dot Optoelectronics and

Photovoltaics. Cambridge University Press, 2013.

[2] Cademartiri, L.; Montanari, E.; Calestani, G.; Migliori, A.; Guagliardi, A.; Ozin, G. A.

Size-Dependent Extinction Coefficients of PbS Quantum Dots. J. Am. Chem. Soc. 2006, 128,

10337–10346.

[3] Hongbo Li,ab Dong Chen,a Linlin Li,a Fangqiong Tang,*a Lin Zhanga and Jun Rena.

Size- and shape-controlled synthesis of PbSe and PbS nanocrystals via a facile method. The

Royal Society of Chemistry 2010; 12, 1127–1133.

12

Generalized Plane Piezoelectric Problem: Applicationto Heterostructure Nanowires

H. T. Mengistu1, A. García-Cristóbal1

1Material Science Institute, University of Valencia, Valencia, Spain

Abstract

The possibility to dispose of two-dimensional (2D) approaches to problems originally posed ina three-dimensional (3D) geometry is always desirable since it reduces significantly thecomputing resources needed for numerical studies. In this work we report on a new 2D approachcalled Generalized Plane Piezoelectric (GPP) problem [1] and apply it to the calculation of thestrain and electric fields in heterostructure (core-shell) nanowires. The approach is based on theidea that for systems with infinite length or with large aspect ratio, all the cross sections can beconsidered to be at identical conditions, and hence the strain and electric fields depend only onin-plane coordinates (x_1,x_2) [2]. The GPP approach is able to accommodate piezoelectricproblems with any cross-section geometry, symmetry and a wide range of compatible boundaryconditions. Therefore, it is well suited to treat piezoelectric problems in nanowires of anymaterial type under different kinds of externally applied constraints or stresses and imposedpotentials or surface charges.

As an illustration of the potential applications of the GPP approach, we present a study of thepiezoelectric problem in a lattice mismatched zincblende InN/GaN core-shell nanowire with axisalong the [111] crystallographic direction. The numerical calculations of GPP are performed ona discretized form of the GPP problem in the framework of continuum piezomechanics by usingCOMSOL Multiphysics® software. When compared with results of the equivalent problemsolved by direct 3D calculations, our 2D calculations exhibit an excellent agreement. Thisagreement shows the reliability of the GPP approach to obtain efficiently accurate strain, electricand potential distributions for wire-like systems.

This work has been financially supported by the European Union through the Grant AgreementNo.265073-NANOWIRING of the Seventh Framework Program, and by the Ministry ofFinances and Competitiveness (MINECO) of Spain through Grants CSD2010- 00044 of theProgramme ''Consolider Ingenio 2010'' and MAT2012-33483.

13

Reference

[1]. Tungyang Chen and Donsen Lai, Proc. Soc. Lond A 453, 2689-2713 (1997)

[2]. Chyanbin Hwu, Anisotropic Elastic Plates, Springer, pp. 29-52 (2010)

13b

High-performance PbS colloidal quantum dot photodetectors operating

at telecommunications wavelengths.

1) J. Navarro*,1, P. J. Rodríguez-Cantó1, A. Maulu1, I. Suarez1 R. Abargues2, J. P. Martínez-Pastor1

1)Institut de Ciència dels Materials (ICMUV), Universitat de València,

Catedrático José Beltrán 2, 46980 Paterna, Valencia, Spain

2) Intenanomat S.L. C/Catedrático José Beltrán 2, 46980 Paterna, Spain

*E-mail: Juan.Navarro-Arenas@uv.es

[1] Saran, R., & Curry, R. J. (2016). Lead sulphide nanocrystal photodetector technologies. Nature Photonics, 10(2), 81–92.

doi:10.1038/nphoton.2015.280

[2] Konstantatos, G., & Sargent, E. H. (2007). PbS colloidal quantum dot photoconductive photodetectors:

Transport, traps, and gain. Applied Physics Letters, 91(17), 100–102. doi:10.1063/1.2800805

[3] Tang, J., Kemp, K. W., Hoogland, S., Jeong, K. S., Liu, H., Levina, L., Sargent, E. H. (2011). Colloidal-quantum-dot

photovoltaics using atomic-ligand passivation. Nature Materials, 10(10), 765–771. doi:10.1038/nmat3118

Semiconducting, PbS colloidal quantum dots offer a promising perspective on highly sensitive IR

photodetection [1] because of its particular advantages, combining solution-processing with the spectral

tunability provided by the quantum size effect. However, reported photodetectors to date show deterioration

in performance under the effects of oxidation processes, which give rise to oxide trapping states. The

photoconductive gain originates from the recirculation of holes during trapped electrons lifetime. Long-lived

trapping of the opposite sing carriers increase gain but also lowers the speed of response [3]. Here, we report

on stable and high-performance micro-gap photoconductors (5 µm gap) encapsulated with a transparent

organosilicone (PDMS). The sealed devices show responsivities in the order of 102 A/W and detectivities of

109 jones (1 jones = 1 cm Hz1/2 W-1) at 1550 nm, the most widely used wavelength in optical communication

systems.

For further investigation in this topic, some ideas have been proposed in order to increase the overall device

performance. An absorption enhancement may be achieved by coupling the dots with gold nanoparticles.

The surface plasmon resonance provides intense enhancement of the electromagnetic near-field, gathering

the impinging light and focusing it on the dots located in the vicinities of the MNPs. An additional

performance boost might be achieved by improving charge transport. This can be accomplished by replacing

the synthesis organic capping ligands on the QD surface with inorganic halide anions (Br-, Cl-) ligand

passivators [3].

900 1050 1200 1350 1500 1650

30

40

50

60

70

80

Re

sp

on

siv

ity (

A/W

)

Wavelength (nm)

Figure 1:

Microgap responsivity

curve (left).

Typical photoconductor

device architecture. Not

to scale (right).

14

High-Q one- and two-dimensional phononic cavities

A. L. O. Bilobran1,*

, M. M. de Lima Jr.1,†

, A. Cantarero1 ; P. V. Santos

2

1Materials Science Institute, University of Valencia, PO Box 22085, ES46071 Valencia, Spain 2Paul-Drude-Institut für Festköperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany

*andre.oliveira@uv.es †mmlimajr@uv.es

Bloch oscillations, Wannier-Stark ladders and Landau-Zener tunneling are paradigm quantum

effects. Recently it was demonstrated that these fundamental effects of quantum-wave

transport can be studied with surface acoustic waves (SAWs) propagating in 1D coupled

acoustic cavities [1]. The coupled phononic cavities - a periodic arrangement of metal stripes

within a surface acoustic delay line on piezoelectric substrate - implies a local change in the

SAW propagation properties, which results from the mechanical loading as well as the

screening of the piezoelectric potential underneath the metal stripes. The acoustic field

distribution can be electrically tuned by controlling the potential of the cavities’ electrodes [2].

The goal of the project is to extend this seminal work to 2D tunable phononic cavities as well

as obtaining cavities with high Q-factor for different applications.

[1] M. M. de Lima et al. Phys. Rev. Lett. 104, 165502 (2010).

[2] M. M. de Lima et al. Appl. Phys. Lett. 100, 261904 (2012).

15

Demonstration of a fractional differentiator based on long period gratings in

fiber optics

Luis Poveda-Wong1, Antonio Carrascosa

1, Christian Cuadrado-Laborde

2, José Luis Cruz

1, Antonio

Díez1, Miguel Vicente Andrés

1

1Instituto de Ciencias de los Materiales de la Universidad de Valencia (ICMUV), Valencia, Spain

2Instituto de Física Rosario (CONICET-UNR), Rosario, Argentina

*E-mail: luis.poveda@uv.es

In this work we experimentally characterized a long period grating (LPG) as a device

capable of producing the fractional derivative of the complex envelope of an optical pulse [1],

under certain bandwidth constraints. We proceeded to experimentally prove the behavior of a

LPG as a differentiator by means of a mode-locked ytterbium fiber laser, whose pulses had

21,4 ps of FWHM and central emission at 1038 nm. We fabricated a LPG centered at the

laser’s main wavelength and with similar bandwidth. The results are shown in Figure 1:

Fig. 1. a) Laser pulse at the input of the LPG and b) differentiated pulse at its output.

By measuring the output pulse’s instantaneous frequency with a technique proposed by

Cuadrado-Laborde [2], we concluded that the LPG’s differentiation order was 0,5. This device

was then used for an application in a real-time phase reconstruction procedure that makes use

of 0,5th order photonic differentiators [3].

References

[1] M.V. Andrés and C. Cuadrado-Laborde, “Design of an ultra-broadband all-optical

fractional differentiator with a long-period fiber grating,” Optical and Quantum Electronics 42,

571-576 (2011)

[2] C. Cuadrado-Laborde, A. Carrascosa, P. Pérez-Millán, et al. ”Phase recovery by using

optical fiber dispersion” Optics Letters 39, 598-601 (2014)

[3] L.Poveda-Wong, A. Carrascosa, C. Cuadrado-Laborde, et al. “Instantaneous frequency

measurement by in-fiber 0.5th

order fractional differentiation,” Optics Communications 371,

89-92 (2016)

16

UV-patternable nanocomposite containing CdSe and PbS quantum dots as

miniaturized luminescent chemo-sensors

Pedro J. Rodríguez-Cantó 1,2

1) Intenanomat S.L., Calle Catedrático Beltrán 2, 46980 Paterna, España

2) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José Beltrán

2, 46980 Paterna, Valencia, Spain

*E-mail: pedro.j.rodriguez@uv.es

The role of nanoscience in analytical science has been greatly established for the development

of (bio)chemical sensors with enhanced performance. The design of low-cost,

easy-to-fabricate and portable analytical devices with a low limit of detection (LOD), good

selectivity, high sensitivity and short response time are in high demand.1,2

Part of that has

been made possible by the use of nanomaterials. In particular, (bio)chemical sensors based on

fluorescent quantum dots (QDs) have attracted intense interest because of their excellent

optical and electronic properties compared to the routinely employed fluorescent organic

dyes.3 These properties include size-tunable light emission over a wide range of energies, high

photoluminescence quantum yield (PL QY), narrow emission line width, and good solution

processability.4 In addition, the physicochemical stability of QDs, their extremely large

surface area, as well as the possibility of functionalizing their surface by conjugation with

appropriate molecules make them very attractive nanomaterials for ultrasensitive sensors with

the possibility of multiplex (bio)chemical detection.5

In this work, we have developed a novel multifunctional hybrid polymer-based luminescent

material particularly formulated for photolithography and tested it as a miniaturized

chemosensor. This nanocomposite was formulated with either luminescent CdSe (for the

visible) or PbS (for the near-IR) colloidal QDs embedded in a polyisoprene-based photoresist

(PIP). The resulting nanocomposite combined the extraordinary optical properties of the QDs

with the lithographic characteristics of the resist matrix (Fig. 1). Both the optical properties of

QDs and the lithographic performance of the photoresist were preserved after the

incorporation of QDs into the photoresist. We checked the sensing capability of this QD–PIP

nanocomposite using 1 cm2 square patterns as a disposable gas sensor by monitoring the PL

intensity upon exposure to 2-mercaptoethanol (MET) and ethylenediamine (EDA) using two

types of QDs: CdSe and PbS. The transduction mechanism of the sensor is based on the

changes of the QD photoluminescence (PL) when molecules are adsorbed onto the QD

surface. The CdSe–PIP pattern sensor showed a decay of PL when exposed to different

amounts of MET and EDA in vapour and found LOD values around 10-3

ng L-1

and 125 ng

L-1

, respectively (Fig. 2). From the calibration curve, we determined that the binding affinity

17

of MET to CdSe–PIP is around four orders of magnitude higher than that of EDA. We also

observed a linear sensing behavior within a broad concentration range, which allows us to use

CdSe–PIP as quantitative sensor for MET and EDA. Furthermore, the PbS–PIP

nanocomposite showed different sensor responses depending on the target analyte, whereas

the exposure of PbS–PIP sensor to EDA led to the quenching of the QD PL, and exposure to

MET molecules resulted in a 6.5-fold enhancement of the PL intensity. The different

responses of CdSe and PbS QDs to MET can be explained by the difference in the energy of

these QDs valence band top with respect to the redox level of the thiol molecule. In

conclusion, these results demonstrate that a completely disposable sensing platform

technology can be developed using this novel QD–PIP luminescent nanocomposite, which

may also form the basis for the development of miniaturized chemosensors, which may be of

interest for several fields such as the food industry, environmental monitoring, and health.

(left) Fig. 1: Optical microscope pictures of different CdSe–PIP nanocomposite structures on glass

patterned by UV lithography: (a) interdigitates,(b) solid square, and (c) framework. (right) Fig. 2. PL

decay response of CdSe-nanocomposite miniaturized sensor as a function of the mass concentration of

EDA and MET in the vapour phase for an exposure time of 15 min. Inset: linear dependence and

corresponding regression line of the sensor response.

[1] F. S. Ligler, Anal. Chem., 2009, 81, 519.

[2] R. Abargues, P. J. Rodriguez-Canto, S. Albert, I. Suarez and J. P. Martínez-Pastor, J. Mater. Chem.

C, 2014, 2, 908.

[3] U. Resch-Genger, M. Grabolle, S. Cavaliere-Jaricot, R. Nitschke and T. Nann, Nat. Methods, 2008,

5, 763.

[4] Nanocrystal Quantum Dots, ed. V. I. Klimov, CRC Press, Boca Raton, FL, 2nd edn, 2010.

17b

[5] M. F. Frasco and N. Chaniotakis, Sensors, 2009, 9, 7266.

17c

Porous core-shell nanoparticles for biomedical applications

Soledad Roig-Sánchez1*, Jamal El Haskouri1, Pedro Amorós1

1) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José

Beltrán 2, 46980 Paterna, Valencia, Spain

*E-mail: soledad.roig@uv.es

Application of nanomaterials in biomedicine has tremendous potential for the development of

new diagnostic and therapeutic modalities. One of the biggest attractions of the discovery of the

surfactant-templated M41S silicas [1] was the ability of tune their pores (size, length, hierarchy,

etc). However, almost ten years passed before the first studies where mesoporous sílica

nanoparticles (MSN) of the MCM-41 family used for biomedical applications [2] were

published. Currently, the MSN are an excellent platform for the design of multifuncional

materials for biomedical applications due to its ability to be use in diagnosis as well as in

therapy (theragnostic materials). [3]

We have synthesized a diversity of core-shell porous silicas via an adaptation of the so-called

“atrane route” [4], which is based on the use of: 1) a hydroalcoholic reaction medium

supporting the formation of silatranes as inorganic precursors and 2) a cationic surfactant as

supramolecular template and, consequently, as a porogen agent after template removal. We

have used a molar ratio of the reagents according to 2 Si: 7 triethanolamine: 1.1 CTMABr : 4

Alkane : x H2O : y Ethanol (912 ≤ x ≤ 1026; 114 ≤ y ≤ 228).

In the absence of ethanol, we obtain aggregates of nanometric mesoporous particles (UVM-7

type). The alcohol incorporation is a key factor to dispose of an emulsion able to favor the

formation of spherical core-shell particles. By tuning the water/ethanol molar ratio, we can

obtain particles in the 100-1000 nm range. Our objective is the control of a large variety of

parameters: particle diameter, shell thickness, pore size and dispersibility. Additionally, the use

of the atrane method seems to be adequate to incorporate Gd and Fe as heteroelements for the

isolation of nanoparticles of interest in MRI.

[1] J. S. Beck, J. C. Vartuli, W. J. Roth, M. E. Leonowicz, C. T. Kresge, K. D. Schmitt, C. T.-W. Chu, D. H. Olson, E. W.

Sheppard, S. B. McCullen, J. B. Higgins, and J. L. Schlenkert, “A New Family of Mesoporous Molecular Sieves

Prepared with Liquid Crystal Templates,” J. Am. Chem. Soc., no. 114, pp. 10834–10843, 1992.

[2] M. Vallet-Regi, A. Rámila, R. P. Del Real, and J. Pérez-Pariente, “A new property of MCM-41: Drug delivery

system,” Chem. Mater., vol. 13, no. 2, pp. 308–311, 2001.

[3] F. Tang, L. Li, and D. Chen, “Mesoporous silica nanoparticles: Synthesis, biocompatibility and drug delivery,” Adv.

Mater., vol. 24, no. 12, pp. 1504–1534, 2012.

[4] S. Cabrera, J. El Haskouri, C. Guillem, J. Latorre, A. Beltrán-Porter, D. Beltrán-Porter, M. D. Marcos, and P. Amorós,

“Generalised syntheses of ordered mesoporous oxides: The atrane route,” Solid State Sci., vol. 2, no. 4, pp. 405–420,

2000.

18

Characterization of Middle Paleolithic flint from the “Abrigo de la

Quebrada” site (Chelva, Valencia, Spain) by spectroscopic techniques

Clodoaldo Roldán(1)

, Jorgelina Carballo(1)

, Sonia Murcia(1)

,

Aleix Eixea(2)

, Valentín Villaverde(2)

, João Zilhão(2)

(1)Instituto de Ciencia de los Materiales, Universidad de Valencia (ICMUV).

C/ Catedrático José Beltrán, 2, 46980 Paterna (Valencia, Spain).

E-mail: clodoaldo.roldan@uv.es ; jorgelina.carballo@uv.es ; sonia.mascaros@uv.es

(2) Departamento de Prehistoria y Arqueología, Universidad de Valencia.

Av. Blasco Ibáñez, 28, 46010 Valencia. E-mail: alejo.eixea@uv.es ; valentin.villaverde@uv.es

(3 )ICREA-Departament de Prehistòria, Història Antiga i Arqueologia. Universitat de Barcelona. C/

Montalegre 6. 08001 Barcelona. E-mail: joao.zilhao@ub.edu

The information available for the Valencia region on prehistoric raw material sources and

procurement is scant. Systematic studies have been carried out over limited areas only, and

geological mapping of the distribution of the siliceous variants used is nonexistent. As far as

the Valencia province is concerned, research has been limited to isolated classification of

finds from the sites of Parpalló and Cova Negra deposited in museum collections.

This work is concerned with the characterization of the flint samples found at the Middle

Palaeolithic site of the “Abrigo de la Quebrada” (Chelva, Valencia, Spain) and preliminary

analyses using optical and spectroscopic techniques are presented. Forty-one samples of

different types of flint from the Quebrada site and five geological samples collected in the

Chelva area, previously characterized macro and microscopically, were analyzed by EDXRF

and XRD. Additionally, six flint samples from the archaeological sites of “Cova de les

Cendres” (Moraira, Alicante) and “Cova Negra” (Xátiva, Valencia), and three geological

samples from the reference collection of Valencia University, all of them located outside the

Chelva geographical zone, were also analyzed and results are compared with the samples

from the “Abrigo de la Quebrada” site. Cluster analysis (CA) and Principal Component

Analysis (PCA) are used as clustering and data reduction techniques for EDXRF analyses.

Crystalline phases and crystalline index of quartz were used to discriminate between local and

allochthonous flint samples.

Despite the fact that our study is still in its initial stages, these data are consistent with a

highly mobile settlement pattern in the regional Middle Palaeolithic and will allow some

interesting observations pertaining to the use of raw materials and their procurement, thereby

increasing the available information with data on a geographical area that had not been

studied so far.

KEYWORDS: Flint, EDXRF, XRD, Middle Palaeolithic

19

Surface Waves Resonances of a Standard Optical Fiber:

characterization of the elasto-optic effect

X. Roselló-Mechó*, M. Delgado-Pinar, A. Díez and M. V. Andrés

ICMUV, Universidad de Valencia, 46100 Burjassot (Valencia), España

*E-mail: xavier.rosello@uv.es

A standard optical fiber under axial strain exhibits an anisotropic refractive index due to the

elasto-optic effect. This effect has not usually been observed in the conventional applications of

optical fibers since the electromagnetic fields of the optical modes are mainly transversal to the axis of

the fiber. However, there are some novel applications, such as silica nanowires [1], where there is a

significant longitudinal component of the electromagnetic field and the index anisotropy is relevant.

Thus, it is necessary to carry out a tensor analysis of the problem. This is also the case for whispering

gallery modes (WGMs). In this work, we do a complete theoretical study of WGMs considering the

index anisotropy induced by the elasto-optic effect. WGMs have been demonstrated to be useful for

accurate diameter [2] and temperature [3] characterization of optical fibers, since the spectral position

of the WGM resonances of an optical fiber depends on the refractive index of the silica. Thus, any

variation of this parameter will shift the resonances in wavelength. In our case, we measured the

wavelength shift of TE and TM WGM resonances of an optical fiber under axial strain by means of the

setup depicted in Fig. 1(a). The results are shown in Fig. 1(b), where we compared the measurements

(dots) with the simulations (lines) taking into account the tensorial character of the elasto-optic effect.

Fig. 1. (a) Scheme of the experimental setup: R and T stand for reflection and transmission ports. (b) Theoretical (lines) and

experimental (points) relative shift of the TE and TM WGM resonances versus the strain applied to the fiber.

The lines represent the simulation for the following parameters: a = 125µm, p11 = 0.121, p12 = 0.27

and υ = 0.168. Both experimental and simulated results show a good agreement. In conclusion, in this

work we demonstrate the anisotropy of the refractive index of an axially stretched optical fiber, both

theoretically and experimentally.

[1] J. Lægsgaard, “Theory of surface second-harmonic generation in silica nanowires”, J. Opt. Soc. Am. B 27, 1317 (2010).

[2] T. A. Birks, J. C. Knight, and T. E. Dimmick, “High-resolution measurement of the fiber diameter variations using

Whispering Gallery Modes and no optical alignment,” IEEE Photon. Technol. Lett. 12, 182 (2000).

[3] M. Delgado-Pinar, I. L. Villegas, A. Díez, J. L. Cruz, and M. V. Andrés, “Measurement of the temperature profile induced

by the optical signal in FBGs using whispering-gallery modes”, Opt. Lett. 39, 6277 (2014).

20

Tunable Raman scattering in Au nanorods decorated ZnO nanowire hybrid

structures

E. Secco,1 A.Pescaglini,

2 D. Cammi,

3 C. Ronning,

3 N. Garro,

1 and D. Iacopino

2

1) Institute of Materials Science, Universidad de Valencia, Valencia, Spain

2) Tyndall National Institute, University College Cork, Cork, Ireland

3) Institute for Solid State Physics, University of Jena, Jena, Germany

Email: eleonora.secco@uv.es

The large band-gap and the high exciton binding energy as well as the ease of manufacturing make ZnO

nanowires (NWs) suitable for a number of optoelectronic devices, including light-emitting diodes, laser diode

and photodetectors in the UV range[1]. Recently, semiconductor NWs decorated with metal nanostructures have

attracted increasing interest due their high potential for plasmonic applications. For instance, chemically-

synthesized metal nanorods (NRs) have been proposed as an extremely powerful and low-cost tool for light

manipulation due to the ability to support collective electron oscillation, called localized surface plasmon

(LSP)[2]. Harnessing properties of hybrid NW-NRs systems appears to be a promising route towards fabrication

of novel optoelectronic devices with engineered properties and high performances[3]. However, so far only

limited information is available on such systems, mainly due to the lack of reliable fabrication techniques and

limited support from theoretical studies.

We developed two new approaches to fabricate in-plain ZnO NW-Au NRs hybrid systems. The first method,

based on temperature-controlled droplet deposition, was suitable to realize high-yield of hybrid devices with a

selective NRs accumulation on the upper or lateral side of the NW. The second method, designed for NW-field

effect transistor devices, allowed NRs deposition on a target NW by means of electric field-mediated assembly.

Systematic investigation of plasmonic-semiconductor coupling in hybrid structures was carried out by Raman

spectroscopy. The intensity of the A1(LO) polar mode of ZnO measured from an individual hybrid NW

increased by several orders of magnitude when the laser wavelength matched the LSP absorption frequency of

the NRs. Moreover this resonant condition was demonstrated to be tunable from the visible to the infrared

spectrum region by engineering the optical extinction of NRs. The results showed a coupling mechanism

between the phonon mode and the LSP related to the dipole symmetry of the LSP radiation. This demonstrates

that modification with metal nanorods is an effective approach to enhance and manipulate the properties of

single semiconductor NWs and opens a promising scenario for optoelectronic devices with integrated

capabilities and high performance.

Fig.1: a) Au nanorod-ZnO nanowire hybrid nanostructure. Decoration methodologies allow deposition of gold nanorods on top of the

nanowire. b) Comparison between the Raman spectrum of bare ZnO nanowire (black line) and hybrid nanostructure (red line) normalized

to the Si peak. The ZnO A1 (LO) polar mode is detectable only in the hybrid nanostructure.

[1] S. Chu, G. Wang, W. Zhou, Y. Lin, L. Chernyak, J. Zhao, J. Kong, L. Li, J. Ren, J. Liu, Nat Nano, 6 (2011) 506-510.

[2] J.A. Schuller, E.S. Barnard, W. Cai, Y.C. Jun, J.S. White, M.L. Brongersma, Nat Mater, 9 (2010) 193-204.

[3] J.K. Hyun, L.J. Lauhon, Nano Letters, 11 (2011) 2731-2734.

21

Concentration and redirection of light in in metal nanoparticle/polymer

nanocomposites waveguides

M. Signoretto 1*, I. Suárez

1, R. Abargues

2, P. Rodríguez-Cantó

2, V. Chirvony

1, and J.

Martínez-Pastor1

1 C/Catedrático Jose Beltrán 2, ICMUV, University of Valencia, 46980 Paterna, (Spain)

2 Intenanomat S.L, C/Catedrático José Beltrán 2, 46980 Paterna, Spain

* E-mail: sigmatt@uv.es

Metal nanoparticles (MNPs) are potential candidates to provide novel functionalities in

photonic devices [1]. Their exotic optical properties derived from the highly localized surface

plasmon polariton (LR-SPP) can be applied to redirect photons or to concentrate the

electromagnetic energy. For example MNPs have been used to increase efficiency of solar

cells, to construct optical sensors or to confine light in the nanometer scale. Moreover, the

development of layers or patterns of MNPs, creates not only a suitable technique to integrate

these nanostructures in optoelectronic devices, but also a way to tune their optical properties.

In this way we propose a novel technology able to control in situ the size of Au

MNPs embedded in the commercially available resist Novolak (NV). When the MNP-NV

nanocomposite is embedded in a solution of the precursor metal salt, the MNPs can act as a

seed for further MNPs growth [2]. In this way, the intensity and position of the MNP

plasmonic resonance can be tuned with the size of the nanostructures.

The host matrix is a commercially available resist suitable for e-beam or UV

lithography so that the nanocomposite can be patterne and hence can be easily integrated in

different photonic structures. For example, we incorporated the nanocomposite in an optical

waveguide by patterning a MNP-Nv film on a SiO2/Si substrate and then capping with a

PMMA layer [2]. In this way, we demonstrate coupling of normally incident light to the

PMMA waveguide in a broad wavelength range (400-780 nm) with the coupling efficiencies

larger than 1 % measured at the output edge of the waveguide structure [2]. Finally, an active

material was embedded into the PMMA film doped with an organic dye in order to study the

interaction of the dye photoluminescence with the plasmonic resonance of the MNPs. In this

way, a significant enhancement of the PL was detected for the cases when the PL spectrally

overlaps with the plasmon resonance.

1. P. Mulvaney, "Not all that's gold does glitter" MRS Bull., 1009-1014, 2001.

2. Signoretto M., Suárez I., Chirvony V. S., Abargues R., Rodríguez-Cantó P. J., and

Martínez-Pastor J., “Polymer waveguide couplers based on metal nanoparticle-polymer

nanocomposites”, Nanotechnology, vol. 26, no. 47, 475201-475210, 2015.

22