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UBC Theses and Dissertations

Study of the spark spectra of tellurium Joshi, Yoginder N.

Abstract

The spark spectra of Tellurium have been photographed from the infrared to the ultraviolet (9040 Å to 340 Å) on a variety of spectrographs including a 3-metre normal, incidence vacuum spectrograph, a 2-metre grazing incidence vacuum spectrograph, a 21-ft, concave grating spectrograph, a Hilger Medium Quartz and a Hilger large automatic prism spectrograph. Two sources were used -1) a disruptive electrodeless discharge and 2) a condensed spark in helium, The "pole effect" exhibited by the spectral lines excited in the spark enabled us to assign each line to its appropriate ionic parent, either Te I, Te II, Te III, or Te IV. These excitation assignments were confirmed and extended by observations with the electrodeless discharge, which excited all the spectra including Te V and Te VI, by varying the tellurium pressure and the length of the external spark-gap. Out of 6000 lines appearing on our plates 3500 have never been observed earlier. The region 2200 Å - 1300 Å has been photographed systematically for the first time since Lacroute's work (1928). The whole of the observed spectral region has been photographed for the first time under uniform conditions of controlled excitation. These data have been used to confirm, revise and extend the analyses of Te III, Te IV, Te V and Te VI. In both Te III and Te IV the resonance lines have been indentified for the first time. The number of classified lines have been increased from 160 to 560 in Te III and from 25 to 230 in Te IV, while the number of the levels has been increased from 40 to 85 in Te III and from 14 to 56 in Te IV. The values of the ionization potentials have been revised to 29.04 Volts (Te III) and 37.41 Volts (Te IV). The hydrogenic levels in Te IV are fitted by a core polarization parameter A = 715 which involves a core dipole polarizability ∝= 41.1 x 10ˉ²⁸ cm³. The extensions in Te V and Te VI do not involve such basic additions. In Te V, the number of classified lines have been increased from 27 to 156 and in Te VI from 10 to 25. Twenty-four and five levels have been added to Te V and Te VI respectively. The revised values of the Ionization Potentials are 58.63 Volts and 70.90 Volts for Te V and Te VI respectively.

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