I= LASER SPECTROSCOPIC STUDIES OF BOUND AND AUTOIONIZING SERIES OF YTTERBIUM
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Title of Thesis
LASER SPECTROSCOPIC STUDIES OF BOUND AND AUTOIONIZING SERIES OF YTTERBIUM

Author(s)
RAHEEL ALI
Institute/University/Department Details
Department of Physics/ Quaid-i-Azam University, Islamabad
Session
1999
Subject
Physics
Number of Pages
85
Keywords (Extracted from title, table of contents and abstract of thesis)
laser spectroscopic studies, ytterbium,laser excitation schemes, photon resonant excitation, thermionic diode detector

Abstract
The present work is devoted to study the bound and autoionizing Rydberg states of ytterbium employing the multistep and multiphoton laser excitation schemes in conjunction with a thermionic diode ion detector. Different intermediate levels have been used, 6s5dI D2, 6s6p 3pI, 6s7s3 SI and 4f13 (2F7/2)6s2 6d[3/2]I to record the spectra of ytterbium. The 6s5dI D2 intermediate level was populated via a two-photon excitation and the second laser was scanned to observe the l = 1 and 3 Rydberg levels. The 6s6p3 PI intermediate level was populated via single photon excitation and from this level the upper levels were excited via two-photon absorption. As a result, in the bound region, the 6snf 1,3 F3 (9‰ n ‰ 30), 6snpI pI (12 ‰ n ‰ S6), 6snp 3PI (12 ‰ n ‰ SO) and 6snp2 P2 (12 ‰ n ‰ 42) Rydberg series have been observed. Three new levels due to the 4f-innershell excitation 4p13 5d2 6s3 D3, 4f13 5d2 6sI F3 and 4f13 5d2 6s3 G3 , which serve as perturbers have been identified. In order to describe the interchannel interactions among the J = 2 and J = 3 channels, the multichannel quantum defect theory have been used which supplements the level assignments. To approach the levels lying above the first ionization threshold, the 4f13( 2F7/2)6s2 6d[3/2]1 intennediate level was populated via the 6s7s3 S1 level (two-photon excitation) while the third laser was scanned. The first measurements of the even parity autoionizing resonances due to the 4f-innershell excitation are reported using three-color four-photon resonant excitation technique. The 4f13(F7/2)6s2 np[5/2]2 (12 ‰ n ‰ 4S) and 4f13 (2F7/2)6s2 nf [5/2]2 (9 ‰ n ‰ 33) have been observed. The spectral line shapes and their intensities have also been discussed.

Download Full Thesis
1192.75 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
180.76 KB
2 1 Introduction
185.34 KB
  1.1 Introduction 1
  1.2 Two-Photon Transition 2
  1.3 Rydberg Atoms 7
  1.4 Quantum Defect Theory (QDT) 8
  1.5 Multichannel Quantum Defect Theory (MQDT) 10
  1.6 Autoionization 14
  1.7 Layout Of The Thesis 16
3 2 Experimental Set-Up
110.28 KB
  2.1 Introduction 17
  2.2 Laser System 17
  2.3 Thermionic Diode Detector 20
4 3 Two-Color Three-Photon Excitation Of The 6snf 1 ,3 F 3 And 6snp 1 p 1 , 3 p 1,2 Rydberg Levels Ofybi
293.41 KB
  3.1 Introduction 25
  3.2 Experimental 27
  3.4 Results And Discussion 27
5 4 Resonant Two-Photon Excitation From The 6s6p 3 P 1 Intermediate Level Of Neutral Ytterbium
201.54 KB
  4.1 Introduction 43
  4.2 Experimental Set-Up 44
  4.3 Results And Discussion
6 5 Multi-Photon Study Of The Bound And Autoionized Spectra Of Ytterbium In The Wavelength Region 505 - 415 Nm
201.54 KB
  5.1 Introduction 55
  5.2 Experimental Set-Up 56
  5.3 Results And Discussion 56
7 6 Three-Color Four-Photon Resonant Excitation Of The Even Parity ' Autoionizing Resonances In Ybl
231.6 KB
  6.1 Introduction 64
  6.2 Experimental Set-Up 67
  6.3 Results And Discussion 67
8 7 Conclusion
94.43 KB
  7.1 References 82