ELECTRONIC, VIBRATIONAL AND EPR STUDIES OF SOME IMPURITY DOPED ALKALI HALIDE CRYSTALS
RISAL SINGH
Thesis submitted to
INDIAN INSTITUTE OF TECHNOLOGY, DELHI for partial fulfilment of the Degree of
DOCTOR OF PHILOSOPHY July, 1973
ACKNOWLEDGEMENTS
The author is grateful to Professor SoC. Jain for supervising the work reported here. The author gratefully acknowledges the benefit of scientific discussions with Dr. S.K. Agarwal. Dr. Agarwal made several useful suggestions, which have improved the thesis considerably.
The author has had the benefit of discussions with Drs. R.K. Jain, A.V.R. Warrior, T.Rs. Reddy and
other scientists of Solid State Physics Laboratory, Delhi and Indian Institute of Technology, Delhi. The author is indebted to all of them. Thanks are due to Hr. Girish Chandra for extending his help in growing crystals.
The author wishes to thank Dr. R.C. Tyugi, SSPL, Delhi and Professor V.K. Gupta, Meerut College, Hoorut for encouragement during the course of this work.
CONTENTS
Acknouledgements
0. ii
CHAPTER 1 SURVEY OF EARLIER WORK AHD INTRODUCTION „ TO PRESENT IHVESTIGATIONS•
1.1 Introduction. ..
1.2 Electronic Spectra of Elemental Impurity Centres.
1.3 Electronic Spectra of Molecular Complexes.
1 1 5 1.3.1 Crystal Field Theory 6 1.3.2 Ligand Field Theory .. 7 1.3.3 Molecular Orbital Theory .. 9 1.3.4 Selection Rules 11 1.3.5 Charge Transfer Spectra .. 13 1.3.6 Electronic Spectra of
Inorganic Tetrahedral
Complexes. .. 15
1.4 EPR Absorption Spectra 18 1.5 Vibrational Spectra .. 21 1.5.1 Vibrational IR Spectra 22 1.5.2 Vibrational Raman Spectra .• 23
References 4.. 2?
CHAPTER II EXPERIP04 AL TECIVIQUES 31 2.1 Growth of Pure and Impurity Doped
Single Crystals of Alkali Halides. 31 2.2 Estimation of Impurity
Concentration. .. 33
CHAPTER III
2,3 Additive and Electrolytic Colour-
ation of Crystals. .. 35 2.4 Thermal Treatment 36 2.6 Optical Absorption Measurements 36 2.6 Raman Scattering Measurements .. 37 2,7 Infrared Measurements .. 37 2.8 Electron Paramagnetic Resonance
Measurements .. 38
References .. 39
ELCCTROC/C AND EPR SPECTRA OF LEAD
CENTRES IN ALKALI HALIDE CRYSTALS 04 40
Abstract .0 40
3.1 Introduction • 42
3.2 Optical Absorption Spectra of Lead
Centres in. Or and IQ Crystals .. 43 3.3 Optical and EPR Absorption Spectra
of Electrolytically/Additively
Coloured Lead Doped IC1 Crystals. ,. 46
3.3.1 Results • 46
3.3.1.1 Electrolytically
Coloured Crystals. 46 3.3.1.2 Additive Coloured
Crystals. .. 47 3.3.1.3 Effect of Heat
Treatment. 61
3.3.1.4 Effect of Removing
Or Ions. 52
3.3.1.5 EPI Absorption
Spectra 63
3.3.2 Discussion • • 54
References 69
CHAPTER ry
CHAPTER V
(V)
OPTICAL ABSORPTION STUDIES OP 110; AND IN ALKALI HALIDE CRYSTALS.
4 01
Abstract. • • 61
4.1 Introduction. .. 62
4.2 Theory. 62
4.2.1 Vibronic Transition
Probabilities. .. 03 4.2.2 Integrated Intensity of
Zero phonon Line. 64 4.2.3 integrated Intensity of
Vibronic Band. .. GB 4.2.4 Interaction with Localized
Vibrations. •• 66
4.3 Results. .. 67
4.3.1 UnO; Doped Crystals. 67 4.3.2 Vh02'" Doped Crystals 4
..69
4.4 Discussion. 69
4.4.1 MO; Bands. •• 69
4.4.2 Vat Bands .. 74
References. •• 77
INFRARED AUD RATTAN SPECTRA OF ALKALI HALIDE CRYSTALS DOPED WITH Unqf NnOt
AND 17o04 70
Abstract, • . 79
5.1 Introduction. 81
5.2 Results. 82
5.3 Discussion.
.. 845.3.1 MO"' Doped Crystals.
..84
01,01"
