I= Laser Spectroscopic Studies of Bound and Autoionizing Spectra of Tin
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Title of Thesis
Laser Spectroscopic Studies of Bound and Autoionizing Spectra of Tin

Author(s)
ALI NADEEM
Institute/University/Department Details
Department of Physics/ Quaid-i-Azam University, Islamabad
Session
2000
Subject
Physics
Number of Pages
75
Keywords (Extracted from title, table of contents and abstract of thesis)
laser spectroscopic studies, autoionizing spectra, tin, yag laser, dye-laser, two step laser excitation

Abstract
The present work have been carried out to study the even parity bound and autoionizing spectra of tin using the two-step laser excitation technique in conjunction with an atomic beam apparatus. We have used two intermediate levels 5p6s(l/2,1/2)( and 5p6s(3/2,1/2)1 to record the spectra of tin. In the first experiment the 5p6s(l/2,1/2)( intermediate level at 34914.20 ± 0.02 cm-1 was populated using the second harmonic of the first dye laser and the second laser was scanned up to the first ionization threshold. The 5pnp (1/2,3/2)2 (II ‰ n ‰ 45) and 5pnp (1/2,3/2)1 (12 ‰ n ‰ 18) Rydberg series have been observed for the first time. In addition, five p-levels 5p8p (3/2,1/2)1,2, 5p8p (3/2,3/2)0,1,2 and three f-levels 5p5f (3/2,5,2)1,2 and 5p5f (3/2,7/2)2 attached to the second ionization threshold have been detected. The inter-channel interactions among the J = 2 levels were studied using the three channel model of the phase shifted quantum defect theory. In the subsequent experiments, the 5p6s(3/2,1/2)1 intermediate level at 39257.1± 0.02 cm-1 was selected as a first step excitation. As a result, new data on the 5pnf (1/2,5/2)2 (12 ‰ n ‰ 46), 5pnp (1/2,1/2)1 (20 ‰ n ‰ 31) and 5pnP (1 /2,3/2)2 (16 ‰ n ‰ 56) Rydberg series have been acquired. The interactions among the 5pnf (1/2,5/2)2 and the 5pnf (3/2,5/2)2 series has been studied using a two channels quantum defect theory. In addition the even parity autoionizing resonances between the 5p2PI/2 and 5p2P3/2 ionic limits tin, excited from the 5p6s 1P1 (3/2,1/2)1 intermediate level have been detected. The Rydberg series are assigned as 5pnf(3/2,7/2)2 (6 ‰ n ‰ 34), 5pnf(3/2,5/2)2 (6 ‰ n ‰ 18), 5pnf (3/2,5/2)1 (6 ‰ n ‰ 11), 5pnp (3/2,1/2)2 (9 ‰ n ‰ 37), 5pnp (3/2.1/2)1 (9 ‰ n ‰ 18), 5pnp (3/2,3/2)2 (9 ‰ n ‰ 27) and 5pnp (3/2,3/2)1 (9 ‰ n ‰ 18). The observed spectra in the autoionizing region are simulated within the framework of the multi-channel quantum defect theory. In all, we report about 200 new even-parity bound and autoionizing levels in the spectra of neutral tin for the first time.

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880.17 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
117.36 KB
2 1 Introduction
118.76 KB
  1.1 Introduction 1
  1.2 Multi-step Excitation 2
  1.3 Ryberg Atoms 4
  1.4 Quantum Defect Theory (QDT) 5
  1.5 Multichannel Quantum Defect Theory (MQDT) 7
3 2 Experimental Set-Up
127.66 KB
  2.1 Introduction 13
  2.2 YAG Laser 13
  2.3 Dye-Laser 13
  2.4 Second Harmonic Generation (SHG ) 16
  2.5 High Temperature Atomic Beam Apparatus 18
  2.6 Data Acquisition System 20
  2.7 Wavelength Calibration 21
4 3 Two-step laser excitation of the even- parity Rydberg levels of tin.
188.4 KB
  3.1 Introduction 23
  3.2 Excitation Scheme 25
  3.3 Results and Discussion 26
5 4 Two-step laser excitation of the even-parity np and nf J =1 ,2 Rydberg levels of tin
185.51 KB
  4.1 Introduction 38
  4.2 Excitation Scheme 39
  4.3 Results and Discussion 40
6 5 Two-step laser excitation of 5P 3\ 2 np , nf autoionizing Rydberg levels of tin.
187.54 KB
  5.1 Introduction 52
  5.2 Excitation Scheme 53
  5.3 Results and Discussion 55
7 6 Conclusion 69
67.76 KB
  6.1 References 73