I= MULTI-STEP LASER EXCITATION OF AUTOIONIZING LEVEL OF LEAD
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Title of Thesis
MULTI-STEP LASER EXCITATION OF AUTOIONIZING LEVEL OF LEAD

Author(s)
Abdul Ahad
Institute/University/Department Details
Department of Physics/ Quaid-i-Azam University Islamabad
Session
2004
Subject
Physics
Number of Pages
89
Keywords (Extracted from title, table of contents and abstract of thesis)
multi-step laser excitation, rydberg states, lead, optical excitation, autoionization

Abstract
We report new data on the highly excited odd parity auto ionizing Rydberg states of lead using three-step laser excitation in conjunction with an atomic beam apparatus. We have used eight different excitation channels to approach the autoionizing levels and the first step in all the excitation schemes was the 6p7s(1/2, 1/2)1, resonance level. In the first series of experiments four intermediate levels 6P3/2 7p1/2, 3/2 J =1,2 attached to the 6p3/2 ionic level and lying below the 6pl/2 ionization limit were populated. These even-parity levels act as perturbers to the 6pnp(1/2, 3/2)2,1 and 6pnf(1/2,5/2)2 even parity Rydberg series converging to the 6pl/2 limit. The excited states have been assigned as 6pnd3/2[1/2]0,1.(13 ‰ n ‰ 38), 6pnd3/2[3/2]1.(13 ‰ n ‰ 37), 6pnd3/2[5/2]2,3 .(13 ‰ n ‰ 37), 6pnd3/2[7/2]3 .(16 ‰ n ‰ 39), and 6pns3/2[3/2]1,2 .(14 ‰ n ‰ 40) Rydberg series. Two hundred and thirty new autoionizing Rydberg levels have been observed and assigned using the jck-coupling scheme. All the series exhibit constant quantum defects with respect to the 73900.65 cm-1 ionization potential. In subsequent experiments, the 6p7f1/2[5/2]2 and 6p8f1/2[5/2]1 levels were used as intermediate levels. About thirty more levels of the 6p3/2ns (J = 1, 2, 11 ‰ n ‰16) and 6p3/2nd (J = 1, 2, 3, 10 ‰n ‰15) configurations have been added on the lower energy side to the observed list. These spectra are similar to those obtained via the 6p7p3/2[5/2]2 intermediate level. This shows that the 6p8f1/2[5/2]2 and 6p7f1/2[5/2]2 levels possess large 6p7p3/2[5/2]2 character. In an attempt to record the autoionizing resonances close to the 6pl/2 ionization limit, we have used the 6p5f1/2[5/2]2 and 6p6f1/2[5/2]2 levels as second step intermediate levels. In these experiments seventeen states of the 6P3/2ng (5 ‰ n ‰15) configurations and eight more levels of the 6p3/2nd (8 ‰ n ‰9) series have been observed and assigned for the first time. In this way almost complete spectra of the 6p3/2ns, 6p3/2nd and 6P3/2ng J = 1, 2, 3 odd parity autoionizing series between the 6pl/2 and 6p3/2 ionization limits have been observed and assigned. The full widths at the half maximum r of the observed levels have been calculated that reflects the absence of any perturbation in this region.

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2142.46 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
238.87 KB
2 1 Introduction 9
336.36 KB
  1.1 Optical Excitation 10
  1.2 Fine Structure 15
  1.3 Coupling Schemes And Term Symbols 17
  1.4 Rydberg Atom 18
  1.5 Quantum Defects, And Spectral-Line Series 20
  1.6 Autoionization 20
3 2 Experimental Set-Up 25
223.92 KB
  2.1 Introduction 25
  2.2 Pump Laser System 25
  2.3 Dye Lasers 27
  2.4 Atomic Beam Apparatus 29
  2.5 Spectral Lines Energy Calculation 31
  2.6 Gpib Instrument Control And Data Acquisition 33
4 3 Three-Step Laser Excitation Of The 6p 3/2 Ns, Autoionizing Rydberg Levels Via 6p7p 3/2 [5/2] 2 , 6p7p 3/2 [3/2] 2 ,1 And 6p7p 3/2 [1/2] 1 Levels Of Lead 35
529.98 KB
  3.1 Introduction 35
  3.2 Excitation Scheme 37
  3.3 Results And Discussion 39
5 4 Three-Step Laser Excitation Of The 6p 3/2 Ns, Autoionizing Rydberg Levels Via 6p6 f 1/2 [5/2] 2 And 6p8 f 1/2 [3/2] 2 Levels Of Lead 54
328.45 KB
  4.1 Introduction 54
  4.2 Excitation Scheme 56
  4.3 Results And Discussion 57
6 5 Three-Step Laser Excitation Of The 6p 3/2 Ns, Autoionizing Rydberg Levels Via 6p6 f 1/2 [5/2] 2 And 6p5 f 1/2 [3/2] 2 Levels Of Lead 68
597.91 KB
  5.1 Introduction 68
  5.2 Excitation Scheme 70
  5.3 Results And Discussion 71
  5.4 Conclusion 84
  5.5 References 87