I. The Broadening of the Resonance Lines of Rubidium Under Different Homogenous Pressures of its Own Vapor. II. The Broadening, Asymmetry and Drift of Rubidium Resonance Lines Under Homogenous Pressures of Helium and Argon up to 100 Atmospheres

Citation

Ch'en, Shang-Yi (1940) I. The Broadening of the Resonance Lines of Rubidium Under Different Homogenous Pressures of its Own Vapor. II. The Broadening, Asymmetry and Drift of Rubidium Resonance Lines Under Homogenous Pressures of Helium and Argon up to 100 Atmospheres. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/e588-hh67. https://resolver.caltech.edu/CaltechTHESIS:01272025-232610975

Abstract

I. The broadening of the resonance lines of rubidium in absorption under pressures up to 152 mm. Hg of its own homogeneous vapor was studied by means of a 21-foot grating. Under pressures below 1 mm. Hg the broadening of the lines was very symmetrical and the line contours could be described by the dispersion formula, but when the pressure was high the lines exhibited asymmetrical broadening. The ²P_½ component showed red, while the ²P_3/2 component showed violet asymmetry. The broadening of the shorter wavelength component is greater than that of the longer wavelength component. Both lines showed the proportionality of the width with N. The experimental half width is greater than that predicted by Prof. Houston's theory by a factor of 1½.

A narrow band was observed near the shorter wavelength side of the ²P_½ component and a similar one near the longer wavelength side of the ²P_3/2 component

II. The broadening. asymmetry and shift of rubidium resonance lines produced under different pressures of pure helium and argon up to 100 atmospheres were studied. The ⁶broadening is linearly proportional to the relative densities of these gases, and is different for different doublet components. The elopes of these half-width vs. relative density curves are .735 cm^-1 and .594 cm^-1 per unit relative density of helium for ²P_1½ and ²P_½ components respectively, and the corresponding values for argon are .855 cm^-1 and .627 cm^-1 per unit relative density. Helium produces a violet, while argon a red asymmetry. The degree of asymmetry increases as the concentration of foreign gas increases, and is comparatively much greater for argon. For argon the asymmetry of the ²P_1½ component is greater than that of the ²P_1½ component, while for helium the reverse is true. Argon produces a greater shift than helium. The former produces a strong red, while the latter a violet shift. For both gases the shift of the ²P_½ component la greater than that of the ²P_1½ oom9onent. For helium the shift appears to be proportional to the relative density. and the shift of the ²P_½ component is about twice as great as that for the shorter wave-length component while for argon the shifts for the doublet components are quite close. and the relation between shifts and relative densities obeys in general the 3/2 power relationship. Optical collision diameters as calculated from the half-width data are 13.37°_A and 7.753°_A for Rb-A and Rb-He respectively. From the measurement of the amount of total absorption of the line contours, f-values and the transition probabilities were evaluated. The f-values turn out to be .33 and .66 for the ²P_½ and ²P_1½ components of the Rb resonance lines respectively.

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