Author: Hong Lam Tran
Publisher:
ISBN:
Category :
Languages : fr
Pages : 61

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Author: Francis Litty
Publisher:
ISBN:
Category :
Languages : fr
Pages : 168

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DETERMINATION DES SECTIONS EFFICACES OPTIQUES DES TRANSITIONS ELECTRONIQUES SOUS EXCITATION OPTIQUE ENTRE LE NIVEAU PROFOND ET LES BANDES DE CONDUCTION ET DE VALENCE RESPECTIVEMENT. CETTE MESURE A ETE EFFECTUEE PAR UN COUPLAGE DES TECHNIQUES DE SPECTROMETRIE TRANSITOIRE DE NIVEAU PROFOND (DLTS) ET DE SPECTROMETRIE OPTIQUE DE NIVEAU PROFOND (DLOS). DEUX CATEGORIES DE NIVEAUX PROFONDS ONT ETE CONSIDEREES. LA PREMIERE DUE AUX METAUX DE TRANSITION CR, FE, CU DONT LES DEUX PREMIERS ONT ETE ANALYSES EXTENSIVEMENT (SECTIONS EFFICACES OPTIQUES, CORRELATION AVEC LES SPECTRES D'EXCITATION DE LUMINESCENCE, IDENTIFICATION DES ETATS DE CHARGE, TRANSITIONS OPTIQUES); EN CE QUI CONCERNE LE CENTRE RELIE AU FER, IL Y A EU MISE EN EVIDENCE D'UN ETAT EXCITE SITUE A 0,2 ET AU-DESSUS DU NIVEAU FONDAMENTAL EV+0,4 EV. LA DEUXIEME CATEGORIE DE NIVEAUX PROFONDS CONSIDEREE EST D'ORIGINE INCONNUE, MAIS SPECIFIQUE DU MODE D'ELABORATION DU MATERIAU: CENTRES EL2, EL5, HL2(B) ET HL5(A)

Author: JOEL.. LEYMARIE
Publisher:
ISBN:
Category :
Languages : fr
Pages :

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LA SPECTROSCOPIE DES ETATS ELECTRONIQUES INTRINSEQUES ET EXTRINSEQUES EST MENEE DANS L'ARSENIURE DE GALLIUM (GAAS) FORTEMENT DOPE PAR DES IMPURETES MISCIBLES COMME L'ALUMINIUM ET L'INDIUM. LES EXCITATIONS DE L'AZOTE, IMPURETE PEU MISCIBLE, SONT EGALEMENT ETUDIEES SOUS PRESSION HYDROSTATIQUE A BASSE TEMPERATURE DANS LE BINAIRE. A L'AMORCE DE LA FORMATION DE L'ALLIAGE, ON ANALYSE L'INFLUENCE DES ELEMENTS AL ET IN SUR L'ELARGISSEMENT SPECTRAL DE LA RECOMBINAISON DE L'EXCITON LIE A L'ACCEPTEUR NEUTRE (A#OX). LA VARIATION DE L'ENERGIE DE LIAISON DES ACCEPTEURS ET L'ECLATEMENT DES NIVEAUX DE A#OX SONT DEMONTRES DANS (GA,AL)AS. DES EXPERIENCES DE DIFFUSION RAMAN ELECTRONIQUE RESONNANTE VIA LE POLARITON DANS SON ETAT EXCITE (XN=2) SUR LES DONNEURS NEUTRES SONT MENEES DANS GAAS ET (GA,AL)AS. ON RELEVE QUE LA POSITION DE LA REPLIQUE NE SE SITUE PAS A UNE ENERGIE STRICTEMENT CONSTANTE DE L'EXCITATION ET QUE SON AMPLITUDE EST MAXIMALE HORS DE LA RESONANCE XN=2. LA SPECTROSCOPIE APPROFONDIE DE L'AZOTE CONDUIT A LA PREMIERE MISE EN EVIDENCE DE LA MOLECULE EXCITONIQUE LIEE A L'IMPURETE DANS GAAS. CETTE DECOUVERTE CONTRIBUE A L'IDENTIFICATION D'UN BIEXCITON LIE A N DANS GA(AS,P) ET (GA,IN)P. L'INTERACTION D'ECHANGE ELECTRON/TROU DE L'EXCITON LIE A N EST MESUREE. SUR LE PLAN INSTRUMENTAL, LES CONDITIONS REELLES DE PRESSION DANS UNE ENCLUME PIERMARINI SONT DETERMINEES PAR L'ANALYSE DE LA CONTRAINTE UNIAXIALE RESIDUELLE ET DE L'INHOMOGENEITE DE PRESSION. TOUJOURS SOUS PRESSION, L'INFLUENCE DU CROISEMENT DE BANDE DIRECTE-INDIRECTE SUR LES NIVEAUX ELECTRONIQUES EST ETUDIEE DANS GAAS. L'IDENTIFICATION DE LA RECOMBINAISON D'UN ELECTRON PIEGE SUR LE NIVEAU D'UN DONNEUR DEPENDANT DES MINIMA X DE LA BANDE DE CONDUCTION AVEC UN TROU LIBRE DE LA BANDE DE VALENCE PERMET DE DEDUIRE, DANS LE CADRE DE L'APPROXIMATION DE LA MASSE EFFECTIVE, L'ENERGIE DE LIAISON DU NIVEAU ET LE COUPLAGE INTERVALLEES DU AU POTENTIEL DU DONNEUR

Author: Agnes Buka
Publisher: World Scientific
ISBN: 1848167997
Category : Science
Languages : en
Pages : 299

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Book Description
The book intends to give a state-of-the-art overview of flexoelectricity, a linear physical coupling between mechanical (orientational) deformations and electric polarization, which is specific to systems with orientational order, such as liquid crystals. Chapters written by experts in the field shed light on theoretical as well as experimental aspects of research carried out since the discovery of flexoelectricity. Besides a common macroscopic (continuum) description the microscopic theory of flexoelectricity is also addressed. Electro-optic effects due to or modified by flexoelectricity as well as various (direct and indirect) measurement methods are discussed. Special emphasis is given to the role of flexoelectricity in pattern-forming instabilities. While the main focus of the book lies in flexoelectricity in nematic liquid crystals, peculiarities of other mesophases (bent-core systems, cholesterics, and smectics) are also reviewed. Flexoelectricity has relevance to biological (living) systems and can also offer possibilities for technical applications. The basics of these two interdisciplinary fields are also summarized.

Author: Jerome V. Moloney
Publisher: Springer Science & Business Media
ISBN: 9780387985817
Category : Business & Economics
Languages : en
Pages : 270

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Book Description
Mathematical methods play a significant role in the rapidly growing field of nonlinear optical materials. This volume discusses a number of successful or promising contributions. The overall theme of this volume is twofold: (1) the challenges faced in computing and optimizing nonlinear optical material properties; and (2) the exploitation of these properties in important areas of application. These include the design of optical amplifiers and lasers, as well as novel optical switches. Research topics in this volume include how to exploit the magnetooptic effect, how to work with the nonlinear optical response of materials, how to predict laser-induced breakdown in efficient optical devices, and how to handle electron cloud distortion in femtosecond processes.

Author: David Adler
Publisher: Springer Science & Business Media
ISBN: 1489922601
Category : Science
Languages : en
Pages : 448

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Book Description
The Institute for Amorphous Studies was founded in 1982 as the international center for the investigation of amorphous mate rials. It has since played an important role in promoting the und er standing of disordered matter in general. An Institute lecture series on "Fundamentals of Amorphous Materials and Devices" was held during 1982-83 with distinguished speakers from universities and industry. These events were free and open to the public ,and were attended by many representatives of the scientific community. The lectures themselves were highly successful inasmuch as they provided not only formal instruction but also an opportunity for vigorous and stimulating debate. That last element could not be captured within the pages of a book I but the lectures concentrated on the latest advances in the field I which is why their essential contents are he re reproduced in collective form. Together they constitute an interdisciplinary status report of the field. The speakers brought many different viewpoints and a variety of back ground experiences io bear on the problems involved I but though language and conventions vary I the essential unity of the concerns is very clear I as indeed are the ultimate benefits of the many-sided approach.

Author: Canada. Patent Office
Publisher:
ISBN:
Category : Copyright
Languages : en
Pages : 1070

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