Procese optice in monocristalele de tip spinel ż-ZnAl2S4 dopate cu ioni ai metalelor de tranzişie

SUMMARY   -----------------  5
LIST OF ABBREVIATIONS ----------  8
INTRODUCTION  -----------------------  9
I. LITERATURE ANALYSIS AND THEORY OF OPTICALLY ACTIVE CENTRES  ----- 14
1. Literature analysis  ----------------- 14
1.1 A brief description of the literature dealing with Spinel structures  --  14
1.2 Titanium ions as transition metal dopant in different matrices  ------------  17
1.3 Cobalt ions as transition metal dopants in different matrices  ----------------------  21
1.4 Vanadium ions as transition metal dopants in different matrices  -----------------  25
2. Theory of the optically active centres ------------------ 31
2.1. Introduction: static interaction, Schrödinger equation and theory of crystalline field  ---------  31
2.2 The crystalline field on d1 optical ions  -----------  34
2.3 Group theory and spectroscopy ------------------  39
2.4 Splitting of energy levels in crystal field -----------------------  44
2.5 Several d electrons in crystalline field of ligands. Case of weak field --------------  45
2.6 Strong crystalline field and low- and high-spin complexes -----------------  47
2.7 Arbitrary ligand fields and Tanabe–Sugano diagrams  ---------------  50
2.8 Qualitative interpretation of vibrational broadening: the configurational coordinate diagram
  ---------------  51
II. CRYSTAL GROWTH, STRUCTURAL CHARACTERISATION AND EQUIPMENT

FOR MEASUREMENT OF OPTICAL PROPERTIES -------- 56
1 Introduction ------------------------ 56
2. Theoretical and Experimental Aspects of the Chemical Vapour Transport (CVT)
Reactions  ------------------------------------------------ 57
3. Synthesis and structural characterization of α – ZnAl2S4 by the CVT method ------ 61
4. Measurements of absorption spectra --------------------------------- 66
5 Measurements of radiative properties ---------------------------- 69
III. SPECTROSCOPIC CHARACTERIZATION OF CO AND V-DOPED α-ZnAl2S4
SPINEL TYPE SINGLE CRYSTALS  --------------------------- 76
1. Introduction --------------------------- 76
2. Spectroscopic characterization of Co -doped α-ZnAl2S4 spinel type single crystals  77

3. Spectroscopic characterization of V-doped α-ZnAl2S4 spinel type single crystals  --- 84
IV. SPECTROSCOPIC CHARACTERIZATION OF Ti-DOPED  α-ZnAl2S4 SPINEL
TYPE SINGLE CRYSTALS  ------------------------- 97
1. Introduction ------------------------- 97
2. Experimental results  ---------------------------------- 98
3. Theory and interpretation of the experimental data -------------- 105
CONCLUSIONS  -------------------------------------- 113
BIBLIOGRAPHY --------------------- 115