Electronic and atomic relaxation processes in pre-irradiated rare gas matrices [Elektronische Ressource] / Galyna Gumenchuk

Sujets

• Physik

Informations

• Publié par: technische_universitat_munchen
• Publié le: 01 janvier 2007
• Nombre de lectures: 9
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Technische Universitat¨ Munchen¨
Fakultat¨ fur¨ Chemie
– Lehrstuhl II fur¨ Physikalische Chemie –
Electronic and Atomic Relaxation Processes
in Pre irradiated Rare Gas Matrices
Galyna Gumenchuk
Vollstandiger¨ Abdruck der von der Fakultat¨ fur¨ Chemie der Technischen Universitat¨
Munchen¨ zur Erlangung des akademischen Grades eines
Doktors der Naturwissenschaften
genehmigten Dissertation.
Vorsitzender: Univ. Prof. Dr. Johann P. Plank
¨Prufer der Dissertation:
1. Univ. Prof. Dr. Vladimir E. Bondybey, Ph. D.
(University of California, Berkeley/USA), i.R.
2. Univ. Prof. Dr. Klaus Kohler¨
Die Dissertation wurde am 13.06.2007 bei der Technischen Universitat¨ Munchen¨
¨ ¨eingereicht und durch die Fakultat fur Chemie am 18.07.2007 angenommen.Electronic and Atomic
Relaxation Processes
in Pre-irradiated
Rare Gas MatricesElectronic and Atomic
Relaxation Processes
in
Pre-irradiated
Rare Gas Matrices
Dissertation
Galyna Gumenchuk?c 2007, Galyna B. Gumenchuk
All rights reservedTo my Family
”The Frontiers of Knowledge (to coin a phrase) are always on the move.
Today’s discovery will tomorrow be part of the mental furniture of every
research worker. By the end of next week it will be in be very course of
graduate lectures. Within the month there will be a clamour to have it
in the undergraduate curriculum. Next year, I do believe, it will seem so
commonplace that it may be assumed to be known by every schoolboy.”
Cavendish Laboratory, Cambridge
”Principles of the Theory of Solids”
by
J.M. Ziman, F.R.S.
Melville Wills Professor of Physics in the University of BristolContents
Contents i
List of Figures iv
List of Tables vi
Introduction 1
Part I 5
1 Theoretical Background 7
1.1 Crystals structure . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.2 Electronic states . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.3 Excitons – excited electronic state . . . . . . . . . . . . . . . . . . 10
1.4 Defects formation . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.4.1 Structural defects . . . . . . . . . . . . . . . . . . . . . . . 13
1.4.2 Radiation induced defects . . . . . . . . . . . . . . . . . . . 13
1.4.3 Defects stability. Annealing. . . . . . . . . . . . . . . . . . 21
1.5 Desorption as surface analogy of defects formation via electronic
subsystem in the bulk of the sample . . . . . . . . . . . . . . . . . 21
2 Activation Spectroscopy 27
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.2 Photon stimulated current spectroscopy and luminescence. Method
of analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.2.1 Measurement methods . . . . . . . . . . . . . . . . . . . . 29
2.2.2 Method of analysis . . . . . . . . . . . . . . . . . . . . . . 29
2.3 Thermoluminescence. . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.3.1 Thermolumunescecne measurement methods . . . . . . . . 32
2.3.2 Thermoluminescence mechanism . . . . . . . . . . . . . . 32
2.3.3 Methods of analysis . . . . . . . . . . . . . . . . . . . . . . 35
2.3.4 Thermally stimulated exoelectron emission (TSEE) . . . . . 35
Part II 37
iii CONTENTS
3 Experimental Setup 39
3.1 chamber . . . . . . . . . . . . . . . . . . . . . . . . 39
3.1.1 Cryostat and vacuum system . . . . . . . . . . . . . . . . . 39
3.1.2 Sources of electrons . . . . . . . . . . . . . . . . . . . . . . 40
3.2 Sample preparation . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.2.1 Deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.2.2 Charge center generation and formation of metastable cen
ters as atomic N or O . . . . . . . . . . . . . . . . . . . . . 42
3.2.3 Annealing procedure . . . . . . . . . . . . . . . . . . . . . 43
3.3 Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.3.1 Activation spectroscopy . . . . . . . . . . . . . . . . . . . . 43
3.3.2 Laser stimulated measurements . . . . . . . . . . . . . . . . 45
3.3.3 Registration of spontaneous and stimulated luminescence . . 47
3.3.4 Re of exoelectron emission . . . . . . . . . . . . . 48
3.3.5 Registration of the anomalous low temperature sputtering . . 49
3.4 New experimental setup for simultaneous measurements of the the
relaxation process: TSL, TSEE and anomalous low temperature des
orption. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4 Experimental Results and Discussion 53
4.1 Energy band model and relaxation channels in RGS . . . . . . . . . 53
4.2 Recombination of self trapped holes with electrons and exoelectron
emission from pre irradiated solid Ar stimulated by external photon
source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.2.2 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.2.3 Results and discussion . . . . . . . . . . . . . . . . . . . . 59
4.2.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.3 Relaxation paths stimulated by ”internal source” of light: key role
2 4of N radicals radiative decay forbidden transition D → S . . . . . 69
4.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.3.2 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.3.3 Results and discussion . . . . . . . . . . . . . . . . . . . . 70
4.3.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.4 Oxygen driven relaxation processes in pre irradiated Ar solids: re
∗laxation channels stimulated by chemiluminescence of O . . . . . . 742
4.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 74
4.4.2 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.4.3 Results and discussion . . . . . . . . . . . . . . . . . . . . 75
4.4.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 86
4.5 A new post irradiation phenomenon in Cryocrystals: anomalous low
temperature sputtering of solid Ar. . . . . . . . . . . . . . . . . . . 87
4.5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.5.2 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . 88