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Title of Thesis

Muhammad Shafqat Mahmood
Institute/University/Department Details
Department of Physics/ Quaid-i-Azam University, Islamabad
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
photo-absorption spectroscopy, alkali metals, innershell excitation, double excitation, sodium, rubidium, cesium, valence shell excitation

The aim of the reported work was two fold; (i) to design and fabricate a three meter off-plane Eagle mounting spectrograph to study the absorption spectra of elements in the region from 1900 to 3450 A and (ii) to investigate the innershell excitation and double excitation spectra of sodium, rubidium and cesium recorded at much higher resolution and dispersion in conjunction with the synchrotron radiation emitted by the 500 MeV electron accelerator, University of Bonn Germany.

The three meter off-plane Eagle mounting spectrograph has been constructed at the atomic and molecular physics laboratory Quaid-i-Azam University Islamabad, Pakistan, which is equipped with a 5000 lines/mm holographic grating, housed in a wooden box to cover the Rowland circle corresponding to the wavelength region between 1900 to 3450 A. An iron arc has been fixed adjacent to the slit of the spectrograph for the reference wavelengths. A high temperature furnace and a high pressure xenon and mercury arc lamps and deuterium lamp served as the background source of continuum, whereas, photographic films are used to record the spectra. The absorption spectra of lithium (up to n = 56), sodium (n = 59) and potassium (n = 51) in the valence shell excitation region have been recorded and a resolution of the order of :t 0.008 A has been achieved.

The innershell and double excitation spectra of sodium, rubidium and cesium have been studied using an identical spectrograph and synchrotron radiation emitted by the 500 Me V electron accelerator as the background source of continuum. In the spectra of sodium investigated in the region from 260 to 400 A we report 200 new levels, in the spectra of rubidium in the region from 500 to 700 A about 130 new levels and in the spectra of cesium in the region from 600 to 900 A about 300 new levels have been found. The observed levels have been arranged in Rydberg series according to the p-inner shell excitation

mp6 (m+ l)s 2S1/2 †’ mp5(m+ l)s (3p2,1,0, 1p1) ns, nd ,

(where m = 2,4 and 5 for sodium, rubidium and cesium respectively), and to the simultaneous excitation of two electrons, the valence electron and one of the p-subshell electron

mp6 (m+l)s 2S1/2 †’ mp5 md nl

Rydberg series attaching to the doubly excited ionic levels, eleven in sodium, three in rubidium and four in cesium have been identified. The interchannel interactions among the overlapping series have also been studied using the multichannel quantum defect theory.

Download Full Thesis
9617.51 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents 0
150.69 KB
2 1 Introduction 1
170.29 KB
  1.1 Thesis Layout 2
  1.2 The Spectra Of Alkali Metals 5
  1.3 Emission Spectra 5
  1.4 Absorption Spectra 7
  1.5 Fine Structure 9
  1.6 Inner-Shell And Double Excitation Spectra 10
  1.7 Configuration Mixing 11
  1.8 Autoionization 12
  1.9 Multichannel Quantum Defect Theory 13
3 2 Construction Of A 3-Meter Spectrograph 14
763.23 KB
  2.1 Main Parts Of The Spectrograph 14
  2.2 Wavelength Standards For The Spectrograph 15
  2.3 Results And Discussion 18
4 3 Valence Shell Excitation Of Alkali Metals 24
3694.11 KB
  3.1 Continuum Light Source 25
  3.2 Vapor Containment System 26
  3.3 Detection / Recording System 26
  3.4 Valence Shell Excitation Spectra Of Lithium, Sodium And Potassium 27
5 4 Inner Shell And Double Excitation Spectra Of Sodium 32
1980.07 KB
  4.1 Summary 32
  4.2 Introduction 32
  4.3 Experimental Procedure 34
  4.4 Results And Interpretation 35
6 5 Inner Shell And Double Excitation Spectra Of Rubidium 57
2979.42 KB
  5.1 Summary 57
  5.2 Introduction 57
  5.3 Results And Interpretation 59