I= TWO-PHOTON LASER OPTOGALVANIC STUDIES OF HELIUM, NEON AND ARGON
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Title of Thesis
TWO-PHOTON LASER OPTOGALVANIC STUDIES OF HELIUM, NEON AND ARGON

Author(s)
Naveed Khaliq Piracha
Institute/University/Department Details
Department of Physics/ Quaid-i-Azam University, Islamabad
Session
1997
Subject
Physics
Number of Pages
102
Keywords (Extracted from title, table of contents and abstract of thesis)
photon laser, optogalvanic studies, helium, neon, argon, single-colour two-photon laser optogalvanic studies, rydberg levels, metastable states, optogalvanic spectroscopy, optical excitation, stark effect

Abstract
Single-colour two-photon laser optogalvanic studies of the Rydberg states of helium, neon and argon have been conducted using an excimer pumped dye laser in conjunction with a discharge cell. The low current discharge mostly populates the metastable states which are photo-excited to Rydberg levels. These Rydberg levels are detected by the optogalvanic effect method. The experimental technique employed, enables us to record pure two-photon Rydberg spectra in regions dominated by the one-photon transitions. In these spectra, we also observe two-photon parity forbidden transitions. In helium, the even-parity triplet ns3S (10 ‰ n ‰ 23), nd3D (10 ‰ n ‰ 34) and singlet nd1D (12 ‰ n ‰ 38) Rydberg states have been detected. In addition, the two-photon parity forbidden 2s3S †’ np3P (13 ‰ n ‰ 25) transitions have been investigated and their appearance in the spectra has been ascribed to the Stark effect. In neon, a large number of two-photon odd parity Rydberg series 2p5ns (J = 0, 1, 2) and 2p5nd (J = 2, 3, 4) excited from the three levels of the 2p53s configuration have been recorded and arranged into 19 Rydberg series. The interchannel interaction among the overlapping Rydberg series for the 2p5 (2p3/2)ns and the 2p5(2P1/2) ns' J = 1 is studied using the multichannel quantum defect theory. In argon, the odd-parity Rydberg states 3p5ns (J = 0, 2) and 3p5nd (J = 0 - 4) are excited from the two metastable levels 3p5 4s[3/2]2 and 3p54s'[1/2]0. The observed spectra are arranged into ten Rydberg series. Higher members of the two-photon parity forbidden series 3p5np have also been detected. The interchannel interaction among the 3p5(2P1/2)nd' and the 3p5(2p3/2)ns, nd J = 2 and the 3p5(2P1/2)nd' and the 3p5(2p3/2)nd J = 3 Rydberg series is studied using the multichannel quantum defect theory.

Download Full Thesis
1286.78 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents 0
145.35 KB
2 1 Introduction and Theoretical Background 1
359.76 KB
  1.1 Introduction 2
  1.2 Rydberg atoms 2
  1.3 Optogalvanic spectroscopy 8
  1.4 Stark effect 16
  1.5 Optical excitation 19
  1.6 Layout of the thesis 27
3 2 Experimental Set-Up 29
105.08 KB
  2.1 Discharge cell 29
  2.2 Laser system 29
  2.3 Data acquisition system 30
  2.4 Experimental details 31
4 3 Two-Photon Laser Optogalvanic Studies of the Rydberg States of Helium 35
192.09 KB
  3.1 Introduction 35
  3.2 Results and discussion 36
5 4 Two-Photon Laser Optogalvanic Studies of the Rydberg States of Neon 49
243.54 KB
  4.1 Introduction 49
  4.2 Results and discussion 50
6 5 Two-Photon Laser Optogalvanic Studies of the Rydberg States of Argon 64
265.52 KB
  5.1 Introduction 64
  5.2 Results and discussion 66
7 6 Conclusion 81
101.15 KB
  6.1 References 85