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Volume 11, Num 2 article 7

Towards a new kind of component: Superconductor Single Electron Transistor SSET

M. Boujida and A. Mansouri

 

Single-electron transistors (SETs) are used to perform sensitive charge measurements and are widely discussed as possible components of dense integrated circuit. An exact model for a single-electron transistor (SET) was developed [1] early, within the circuit simulation package SPICE; it's constituted by two tunnel junctions, with two gates coupled to the island. We will present here a description of previews results of SET [1] and our perspective for a superconductor single electron transistor.

Superconducting single-electron transistors (SSET's) are small islands of superconducting material isolated from an external circuit by tunnel barriers (Josephson junctions). The normal tunnel barrier resistances: R >RQ= h / 4e2 » 6.5 KΩ are sufficient to constrain the excess charge on the island to integer multiples of e.

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Key Words: Single electron transistor, SET, SSET, SNS-SET, junction, superconductor.

University of Sidi Mohammed Ben Abdullah Faculty of Science and Techniques Laboratory of Signals Systems and Components Electrical Engineering School, Route Immouzer BP 2202 Fès Morocco

 

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Volume 11, Num 2 article 8

Phase diagrams of site diluted semi infinite ferromagnetic film

R. Masrour (a,*), M. Hamedoun(a), K. Bouslykhane(a), A. Hourmatallah (a,b),

N. Benzakour(a) and A. Filali (a)

        The magnetic susceptibility of a semi-infinite ferromagnetic films with a simple cubic lattice and the face centered cubic lattice is investigated by the method of exact high-temperature series expansions (HTSE) extrapolated with the Padé approximants method for Heisenberg, XY and Ising models. The magnetic phase diagrams in (tc(n), x) plane are obtained. The value of the percolation threshold Xp is obtained. The Xp is defined at which tc=0.

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Keywords: magnetic susceptibility; semi-infinite film; magnetic phase diagrams; percolation threshold.

a: Laboratoire de Physique du Solide, Université Sidi Mohammed Ben Abdellah, Faculté des sciences Dhar
Mahraz, BP 1796, Fes, Morocco.
b: Equipe de Physique du Solide, Ecole Normale Supérieure, BP 5206, Bensouda, Fes, Morocco.
* Corresponding Author e-mail: rachidmasrour@hotmail.com

 

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Volume 11, Num 2 article 9

Analysis of temperature effect on I-V characteristics of silicon (npn) emitter-base

Haddou EL ghazi1,*, Anouar Jorio1,2, Izeddine Zorkani1

The current through silicon emitter-base (npn) junctions is measured for forward and reverse polarizations. The I-V characteristics are presented for unirradiated samples at different temperatures. For forward bias, we have studied the reverse saturation current (IS), the series resistance (RS) and the ideality factor (n) as function of temperature. The temperature effect is more consistent with the generation current from the space charge region. For reverse polarization, we have studied Ln (IR/T1/2) as function of the reciprocal temperature and we found 0.29 eV for the activation energy which is in good agreement with the result obtained from electroluminescence (EL) spectra.

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Keywords: Si junctions, Temperature effect, I-V characteristics, ideality factor, Series resistance, activation energy.

1 Solid State Physic Laboratory, Faculty of Sciences, Dhar El Mehraz, Fez, Morocco.

2 Regional center of interface, Sidi Mohammed Ben Abdellah University, Morocco

*Corresponding Author  Email: hadghazi@gmail.com

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Volume 11, Num 2 article 10

MAGNETIC AND ELECTRIC FIELD EFFECTS ON THE BINDING ENERGY OF A SHALLOW DONOR IN QUANTUM DOT–QUANTUM WELL

K. RAHMANI1, I. ZORKANI1

We studied the simultaneous of the magnetic and electric field effects on the binding energy for a shallow donor confined to move in spherical Quantum Dot – Quantum Well (GaAs-GaAlAs). Calculations are performed in the framework of the effective mass approximation using the Hass variational approach. We describe the effect of the quantum confinement by a infinite deep potential. The result shows that the corrections due to the magnetic and electric field are very important and cannot be neglected or ignored. We have demonstrated the existence of a critical value (a/b)cri which can be used to distinguish the three dimensions confinement from the spherical surface confinement and it’s may be important for the nanofabrication techniques.

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key words: Quantum Dot - Quantum Well, Magnetic Field, Electric Field

* kh.rahmani@enssup.gov.ma

1Groupe de Photoélectronique, LPS, Département de Physique,
Faculté des Sciences Dhar Mehrez, B.P. 1796 Fes, Morocco

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Volume 11, Num 2 article 11

NEW APPROCH TO DETERMINE THE ACCURATE
MINORITY CARRIER LIFETIME

M. Idali Oumhand and M. Zazoui

In the recent years, considerable research has been done on multijunction (MJ) solar cell. A monolithic MJ solar cell is composed of several junctions connected in series, all of which should be closely current matched for efficient photovoltaic device operation. The most successful implementation of this device is the InGaP/GaAs/Ge triple junction cell, attaining efficiencies in excess of 29 % AM0. The degradation of the cell characteristics under the high energy electron and proton irradiation depends on the semiconductor material and the specific solar cell structure.  High energy particles lead to displacement damage and deep recombination centres reducing the minority carrier lifetime.  In the present work, we present a new method, which allows to get exact value of the minority carrier lifetime and to apply this to p+/n InGaP solar cell material..

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L.PM.C. UFR Matériaux en Couches Minces et Systèmes pour la Conversion Photovoltaïque

B. P. 146, Bd Hassan II, F.S.T. Mohammedia, Morocco.

zazouimimoun@yahoo.fr

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Volume 11, Num 2 article 12

The vortex motion and the magnetization study in YBa2Cu3O7-d single crystal

A. Ramzi*, 1, A. Taoufik1, A. Tirbiyine1,2, A. Abaragh1, H. Darhmaoui3, S. Senoussi4, L. Bougarfa1, F. Chibane1, M. Boujida5, A. Labrag1, A. Bouaaddi1 and M. Bghour1

We have investigated the vortex motion and the magnetization of high critical temperature superconductors YBa2Cu3O7-d Measurements were made using a vibrating sample magnetometer technique. Several magnetization hysteresis cycles have been obtained for different angles, θ, between the applied magnetic field, H, and the crystallographic c-axis. For T = 30 K we observed a central peak and for T = 80 K we observed a second peak or "fishtail".

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PACS 74.25.Fy, 74.40.+k

1 Equip of Materials Superconductors at High Critical Temperature, Ibn Zohr University, Agadir, Morocco.
2 Cadi AyyadUniversity, Poly-disciplinary Faculty, B. P. 4162, Route Sidi Bouzid 46000 Safi, Morocco.
3 School of Science and Engineering, Al Akhawayn University, Ifrane, Morocco 53000
4 Solids physics laboratory, Paris-Sud University, Orsay, France.
5 Sidi Mohammed ben Abdellah University, sciences and technic Faculty, B. P. 2202, Route Route d’Imouzzarr Fes, Morocco.

* Corresponding author : ab_ramzi@yahoo.fr

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Volume 11, Num 2 article 13

TEM study of GaN/AlN quantum dots
deposited on vicinal silicon

M. Benaissa1,*, P. Vennéguès2 and F. Semond2

Transmission electron microscopy was performed to investigate the use of AlN epitaxial films deposited on vicinal Si(111) as templates for the growth of GaN quantum dots. It is found that the substrate vicinality induces both a slight tilt of the AlN (0001) direction with respect to the (111) direction and a step bunching mechanism. As a consequence, a dislocation dragging behavior is observed giving rise to dislocation-free areas well suited for the nucleation of GaN quantum dots. The microstructure of different QD encountered in the GaN/AlN system is also described.

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keywords : GaN, quantum dots, dislocation, vicinal substrate, transmission electron microscopy

1 CNRST, Angle Allal Fassi / FAR, B.P. 8027 N.U. , Hay Riad, 10000 Rabat, MAROC

² CRHEA-CNRS, rue Bernard Grégory, 06560 Valbonne, France 

* benaissa@cnrst.ma

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Volume 11, Num 2 article 14

Modelling and simulation of vibrationnal properties of carbon nanotubes and derivatives

A. Rahmani, K. Sbai, H. Chadli and J.-L. Sauvajol*

The aim of the present paper is to identify the main Raman vibrational features of carbon nanotubes and derivatives. In this goal, Raman active mode calculations have been performed on different single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) as well as peapods. The comparison between the calculations performed on these different systems allows us to identify the Raman-active modes of each carbon nanomaterials. In SWCNTs, the tangential modes are located around 1590 cm-1 and the radial breathing mode follows A/D law. This latter law is modified in bundle of SWCNTs, DWCNTs or peapods.

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Keywords: Nanotube, Nanopeapod, Fullerene, Raman spectroscopy, spectral moment method.

Equipe de Physique Informatique et Modélisation des Systèmes, Université MY Ismail, Faculté des Sciences, BP 11201, Zitoune, 50000 Meknès, Morocco

* Laboratoire des Colloïdes, Verres et Nanomatériaux (UMR CNRS 5587),CP026, Université Montpellier II, 34095 Montpellier Cedex 5, France

 

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Volume 11, Num 2 article 15

Photodegradation of 2-naphthol
Using Nanocrystalline T
iO2

S. Qourzal*, M. Tamimi, A. Assabbane and Y. Ait-Ichou

The kinetics of the photocatalytic degradation of 2-naphthol has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions, which is essential from application point of view. The degradation was studied using different parameters such as types of TiO2, catalyst concentration, substrate concentration, reaction pH and in the presence of different electron acceptors such as hydrogen peroxide (H2O2), potassium bromate (KBrO3) and potassium persulphate (K2S2O8) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatlyst ″Degussa P-25″ was found to be more efficient as compared with other photocatalysts. The results indicate the process follows Langmuir-Hinshelwood-type kinetics and inference is made of the reaction taking place on the semiconductor particle surface. An analysis of Total Organic Carbon (TOC) showed that a complete mineralization of 2-naphthol can be easily achieved.

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Keywords: Photocatalysis, Titanium dioxide, 2-naphthol, Water treatment.

Laboratoire de Chimie-Physique, Equipe de Photocatalyse et Environnement, Département de Chimie,

Faculté des Sciences, Université Ibn Zohr, B. P. 8106 Cité Dakhla, 80000 Agadir, Maroc

*Corresponding author: samir_qourzal@yahoo.fr

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Volume 11, Num 2 article 16

Hybrid Nanomaterials Based on Anionic Clays for Application to Water Dichlorophenoxyacetate and-Purification: Cases of 2,4 chlorobenzenesulfonate-4

M. Lakraimi1, A. Legrouri2*, A. Barroug3, A. De Roy4, J. P. Besse4

The elimination of the herbicide 2,4dichlorophenoxycetic acid (2,4D) and the surfactant 4chlorobenzenesulfonic acid (4CBS) from aqueous solutions by the layered double hydroxides (LDHs) through anion exchange and/or adsorption proved to be effective. The interaction of LDHs with these pollutants was investigated by a combination of spectroscopic and physico-chemical methods. Treatment of solutions containing variable concentrations of 2,4D and 4CBS led to their elimination with an uptake ratio of up to 98% for 2,4D and 95% for 4CBS. Infrared spectroscopy and X-ray diffraction indicated that this maximum of retention corresponds to an elimination of the pollutants by exchange reactions, leading to their intercalation between the LDH layers, in addition to adsorption. Thermal decomposition of LDHs samples used in water purification experiments, coupled with mass spectrometry analysis of the evolved gases, allowed to confirm the organic-inorganic hybrid character of the materials.

Key Words: layered double hydroxides, anionic clays, 2,4dichlorophenoxyacetate, 4chlorobenzenesulfonate water treatment, adsorption, anion exchange.

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1 Ecole Normale Supérieure, B.P. S41, Marrakech 40001, Morocco
2 School of Science & Engineering, Al Akhawayn University, PO Box 1871, Ifrane 53000, Morocco.
3 Laboratoire de Chimie-Physique, Faculté des Sciences Semlalia, Université Cadi Ayyad, B.P. 2390, Marrakech 40001, Morocco
4 Laboratoire des Matériaux Inorganiques, UPRES-A 6002, Université Blaise Pascal, 63177 Aubière-Cedex, France

* Correspondence: E-mail: legrouri@aui.ma

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Volume 11, Num 2 article 17

Sol gel synthesis of  multiphase lanthanum oxicarbonate and langasite thin films.

K. Ouzaouit1,2, S. Villain1, A.Essoumhi1, A. Benlhachemi2, H. Benyaich2,  J-R. Gavarri1

Precursors of lanthanum oxide and of (3La2O3, 5Ga2O3, SiO2) system were first elaborated then thermally decomposed into polycrystalline lanthanum oxide and langasite La3Ga5SiO14. The as prepared lanthanum oxide powder was then hydrated and carbonated to give hydroxicarbonates: thermal decomposition of these complex system La2O3-X(OH)y(CO3)z was studied by Fourier Transform infrared spectroscopy. Spin coating process applied to these precursors was optimized to elaborate thin films of lanthanum oxicarbonate La2O2CO3, lanthanum oxide La2O3 and langasite, on silicium substrates (Si-(001)). Thin films are partly textured. Making use of same spin coating process, multiphase thin films of langasite covered with La2O3 particles were obtained.

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Keywords: thin films, sol-gel growth, lanthanum carbonate, X-ray diffraction

1Laboratoire Matériaux & Microélectronique de Provence, L2MP, UMR CNRS 6137, Université du Sud Toulon-Var,

BP 20132,  83957 La Garde, Cedex – France

2Laboratoire Matériaux et Environnement, Faculté des Sciences, Université Ibn Zohr,

BP 8106 Cité Dakhla, 80 000, Agadir - Maroc

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Volume 11, Num 2 article 18

Flux flow noise in high Tc
superconductors thin films

A. Bouaaddi1, A. Taoufik1, A. Labrag1, M. Bghour1, A. Abaragh1, A. Ramzi1, A.Tirbiyine3 and S. Senoussi2

We have studied the fraction pinned of vortex in a type II superconductors. The sample used is the YBa2Cu3O7-d thin films. This fraction pinned is determined from the comparison of the experimental results and the theoretical results previously definite. In continuation one will study the variations of this fraction according to the temperature of the applied magnetic field and the electric current crossing the sample.

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1Laboratory of materials superconductors at high critical temperature, Ibn Zohr University, Agadir, Morocco.

2Laboratory of Solid Physics, Paris-Sud University, Orsay, France.

3Université Cadi Ayyad, Faculté Poly-disciplinaire, B. P. 4162, Route Sidi Bouzid  46000 Safi, Morocco.

Email : abouaaddi@yahoo.fr

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Volume 11, Num 2 article 19

The critical current density and the vortex pinning in high quality YBa2Cu3O7-d thin films

A. Ramzi*, 1, A. Taoufik1, A. Tirbiyine1, 2, A. Labrag1, A. Abaragh1, H. Darhmaoui3, S. Senoussi4, L. Bougarfa1, F. Chibane1, M. Boujida5, A. Bouaaddi1 and M. Bghour1

We have measured the critical current density Jc of high quality c-axis oriented YBa2Cu3O7-d thin films. Measurements were performed for various magnetic field and temperature values, and as a function of the angle q between the c-axis and the applied magnetic field direction. A maximum of the critical current density was obtained when the flux lines are aligned along the CuO planes (q = 90°); another maximum in Jc was also observed when the magnetic field is adjusted parallel to the c-axis. We attribute these effects to different, intrinsic and extrinsic, pinning mechanisms of vortices in the sample.

* Corresponding author : ab_ramzi@yahoo.fr

PACS 74.25.Fy, 74.40.+k

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1 Equip of materials superconductors at high critical temperature, Ibn Zohr University, Agadir, Morocco.

2 Cadi Ayyad University, Poly-disciplinary Faculty, B. P. 4162, Route Sidi Bouzid 46000 Safi, Morocco.

3 School of Science and Engineering, Al Akhawayn University, Ifrane, Morocco 53000

4 Solids physics laboratory, Paris-Sud University, Orsay, France.

5 Sidi Mohammed ben Abdellah University, sciences and technic Faculty, B. P. 2202, Route Route d’Imouzzarr  Fes, Morocco.

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Volume 11, Num 2 article 20

Surface Nanofabrication in Photosensitive Polymers at the diffraction limit of light and down to 47 nm by Metal Tip-Enhanced Near Field light : Light Induced Nanomovement of Polymers

Zouheir Sekkat1-4,*, Hidekazu Ishitobi3, Mamoru Tanabe4, Satoru Shoji4, and Satoshi Kawata3,4

This paper discusses surface nanofabrication in azo-polymers. Nanoscale polymer movement is induced by a tightly focused laser beam in an azo-polymer film just at the diffraction limit of light. The deformation pattern which is produced by photoisomerization of the azo dye is strongly dependent on the incident laser polarization and the longitudinal focus position of the laser beam along the optical axis. The anisotropic nanofluidity of the polymer film and the optical gradient force played important roles in the light induced polymer movement. We also explored the limits of the size of the photo-induced deformation, and we found that the deformation depends on the laser intensity and the exposure time. The smallest deformation size achieved was 200 nm in full width of half maximum; a value which is nearly equal to the size of the diffraction limited laser spot. Beyond the limit of light diffraction, a nano protrusion was optically induced on the surface of the films by metal tip enhanced near-filed illumination. A silver coated tip was located inside the diffraction limited spot of a focused laser beam (460 nm), and an enhanced near-field, with 30 nm light spot, was generated in the vicinity of the tip due to localized surface plasmons. The incident light intensity was carefully regulated to induce surface nanodeformation by such a near-field spot. A nano protrusion with 47 nm full width of half maximum and 7 nm height was induced with a resolution beyond the diffraction limit of the light. The protrusion occurs because the film is attracted towards the tip end during irradiation. At the top of the protrusion, an anisotropic nanomovement of the polymer occurs in a direction nearly parallel to the polarization of the incident light, and suggests the existence at the tip end of not only a longitudinal, i.e., along the tip long axis, but also a lateral component of the electric field of light. The azo-polymer film helps map the electric field in the close vicinity of the tip.

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1 Nanophotonics Laboratory, The Institute of Nanomaterials and Nanotechnology, INANOTECH,Rabat, Morocco
2 Hassan II Academy of Science and Technology, Rabat, Morocco.
3 Nanophotonics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
4 Department of Applied Physics, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871,
Japan
* Author for Correspondence, e-mail: z.sekkat@inanotech.ma

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Volume 11, Num 2 article 21

Raman-Active modes in Homogeneous and Inhomogeneous Bundle of Single-Walled Carbon Nanotubes

K. Sbai, A. Rahmani, H. chadli and J. L.  Sauvajol*

In the present work, the non-resonant Raman active modes were calculated for several diameters, chiralities and sizes for homogeneous and inhomogeneous bundles of single-walled carbon nanotubes (BSWCNT's), using the spectral moment’s method (SMM). Additional intense Raman active modes are present in the breathing-like modes (BLM) spectra of these systems in comparison with a single fully symmetric A1g mode characteristic of isolated nanotubes (SWCNT's). The dependence of the frequency of these modes in terms of diameters, lengths and number of tubes is investigated. We find that for finite bundle, additional breathing-like modes (BLM's) appear as a specific signature. Finally, the effects of the inhomogeneous bundles on the Raman spectra were studied.

Corresponding Author: email kh.sbai@yahoo.fr

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Keywords: Nanotube, non-resonant Raman, Raman spectroscopy, spectral moment method.

Equipe de Physique Informatique & Modélisation des Systèmes, Université MY Ismail, Faculté des Sciences,BP 11201, Zitoune, 50000 Meknès, Morocco.

* Laboratoire des Colloïdes, Verres et Nanomatériaux (UMR CNRS 5587), Université Montpellier II, 34095 Montpellier Cedex 5, France.

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Volume 11, Part 1 article 22

Nonresonant Raman spectrum of C60 nanopeapod: C60 polymerization effects

H. Chadli, A. Rahmani, K. Sbai and  J. L. Sauvajol*

We present a force constants model for the vibrational modes in C60 dimer and polymer phases. The results of this model are used to calculate the nonresonant Raman spectra of infinitely long isolated C60 dimer and polymer peapod in the framework of bond-polarization theory by using the spectral moment’s method. The changes of the Raman spectrum in terms of the structure of the C60 molecules inside the nanotubes are identified. We show that the lowest Raman frequency region of the nanotube is more affected by the C60 chain insertion in comparison with the higher one.

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Keywords: nanopeapod, Fullerene, Raman spectroscopy, nanotube, spectral moment method.

Equipe de Physique Informatique & Modélisation des Systèmes, Université MY Ismail, Faculté des Sciences,BP 11201, Zitoune, 50000 Meknès, Morocco.

* Laboratoire des Colloïdes, Verres et Nanomatériaux (UMR CNRS 5587), Université Montpellier II, 34095 Montpellier Cedex 5, France.

Corresponding author: email abdelali@fsmek.ac.ma.

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Volume 11, Part 1 article 23

Finite size effects on Raman spectrum of single-walled boron nitride nanotube

B. Fakrach, A. Rahmani, H. Chadli and K. Sbai

Using the spectral moments method, we present calculations of Raman active modes of Single Walled Boron Nitride Nanotube (SW-BNNT). The Spectra are computed for chiral and achiral nanotubes in terms of their diameter and length. The behaviors of low frequency Raman active modes characteristic, in terms of the tube diameter revealed that these frequencies are diameter dependent. We show that the number of Raman active modes, their frequencies, and intensities depend on the length and chirality of the nanotubes. These predictions are useful to interpret the experimental Raman spectra of BNNTs.

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Equipe de Physique Informatique & Modélisation des Systèmes, Université MY Ismail, Faculté des Sciences,BP 11201, Zitoune, 50000 Meknès, Morocco.

* Laboratoire des Colloïdes, Verres et Nanomatériaux (UMR CNRS 5587), Université Montpellier II, 34095 Montpellier Cedex 5, France.

Corresponding author: email abdelali@fsmek.ac.ma.

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Volume 11, Num 2 article 24

Surface Optical Waves at Air/Metal Interfaces: Surface Plasmon Polaritons

R. Lghoul, M. Chraibi, I. Maouli, N. Bouzidi, A. Ouardaoui, K. Smith, F. Berrada, K. Loudiyi, H. Darhmaoui and Z. Sekkat*

The surface plasmon resonance (SPR) phenomenon has been known for nearly five decades now; since then this method has made great advances in terms of instrumentation development and applications, and it still attracts researchers because of certain subtle issues that could benefit from it mainly detection and analysis of chemical and biochemical substances in different areas including medicine, environmental monitoring, biotechnology and drug and food monitoring. Our interest is focused on the use of this technique for studying thin coating and some application in nanophotonics. In this paper, we discuss the configuration of surface plasmons at air/metal interface by Atenuated total reflection (ATR) technique in the Kretchman configuration, and we present preliminary experimental results on surface plasmons at a Ag/air interface that we obtained in our laboratory.

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Keywords: surface plasmons, thin films characterization.

Nanotechnology Laboratory, School of Science & Engineering, Al Akhawayn University in Ifrane PO BOX 104, Ifrane, 53000, Morocco.

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Volume 11, Num 2 article 25

Single-Molecule Fluorophores as Environmental Nanoprobes

N. Liua, Z. Lua, H. Ougaddouma, H. Wanga, R. Webera, J. Williamsa, Z. Yanga,
R. Twiega Samuel J. Lordb

The DCDHF dyes are under development as a promising new class of single-molecule fluorophores. The utility of these fluorophores is derived from a range of attributes including their synthetic accessibility, structural versatility and photostability, all permitting a range of practical labelling applications. Their polarity- and viscosity-dependent emission, required for their application as local environment nanoprobes, is of particular interest. A wide range of DCDHF chromophores with different p-systems have been prepared for control of absorption and emission characteristics.  Structure-function analysis has been performed in conjunction with theoretical evaluations of these chromophores.

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Keywords: Single molecule, DCDHF fluorophore, environmental sensitivity.

a Kent State University, Department of Chemistry Kent, Ohio USA 44242

b Stanford University, Department of Chemistry Stanford, California USA 94305