The development of a gas laser system for the measurement of atomic parameters and its application to some energy levels in neon Measurement of atomic parameters

Lilly, Roger Alan
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The development 9f gas lasers has provided the experimental atomic physicist with a new tool for the selective probing of atomic energy levels. This dissertation describes the development of a gas laser system for the measurement of atomic parameters. The system has been applied to the measurement of transition probabilities and collision excitation cross sections in neon. The experimental technique utilizes a helium-neon laser oscillating at 3.39 microns -- 3s2- 3p4 (Paschen notation) -- to perturb the population density of the 3s2 level in a neon discharge. This perturbation is coupled to the 3s3 neon level through non-radiative collision induced transitions. The perturbations of the excited state population densities are followed by observing the intensity changes in spontaneous emission from the 3s2 and 3s3 levels. By analyzing the intensity changes from these two levels as a function of pressure, we have been able to determine the product of the lifetime of the 3s3 level and the cross section for collision induced transitions between the 3s2 and 3s3 levels. This product is τ3q23 = (9.93 ± .80) x 10^-23 sec-cm^2 . The same measurements yield the ratio of the transition probability for the 3s2-2p4 and the 3s3-2p5 transitions. The measured ratio is 7.10 ± .57. In order to be able to vary the pressure, the" atoms to be investigated are contained within a gas discharge cell placed within the laser cavity. A phase sensitive detection system is employed. Relative transition probabilities for ten other visible lines originating on the 3s2 and 3s3 levels have also been determined. These relative transition probabilities are placed on an absolute scale using a recently measured value for the 3s2-2p4 transition. The experimental values are compared to theoretically calculated transition probabilities for which a j-ℓ coupling model was used. This comparison points out the rather large departure of these levels from j-ℓ coupling. Suggestions are made concerning the improvement of the system and its application to other problems.
Bibliography: leaves [127]-130.
viii, 130 l illus., tables
Lasers, Nuclear energy
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Theses for the degree of Doctor of Philosophy (University of Hawaii at Manoa). Physics; no. 175
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