# ABSORPTION SPECTRUM OF $Ar_{2}$ IN THE VACUUM ULTRAVIOLET

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 Title: ABSORPTION SPECTRUM OF $Ar_{2}$ IN THE VACUUM ULTRAVIOLET Creators: Colbourn, E. A.; Douglas, A. E. Issue Date: 1976 Publisher: Ohio State University Abstract: Tanaka and Yoshino have observed absorption from the van der Waals’ ground state of $Ar_{2}$ to 9 chemically bound excited states in the vacuum ultraviolet region. They were unable to resolve rotational structure, but did perform a vibrational analysis. Using the third order of a 10 m concave grating spectrograph, we have photographed the absorption at liquid $N_{2}$ temperature. Rotational structure was seen and analysed for the band systems at longest wavelength (Systems I and II of Tanaka and Yoshino), The analysis of System I (1074-1077 \AA) showed that the bands have P, Q and R branches, but the overlapping of lines was so great that accurate molecular constants could not be determined. In System II (1067-1073 \AA), which shows only P and R branches, the lines suffer from considerable overlapping but there are sufficient sharp absorption peaks to obtain a complete analysis. Absorption bands from $\nu = 0-4$ to 4 vibrational levels of the upper state were analysed. Since the potential well of the lower state is shallow, conventional molecular constants are not readily determined. The spectrum was analyzed in terms of a ground state potential curve and a set of molecular constants (determined by traditional methods) for the $O^{+}_{u}$ upper state. Some of the constants of the ground state are $B_{e} = 0.0598 cm^{-1} \Delta G _{1/2} = 25.82 cm^{-1}$, and $\Delta G_{3/2} = 20.38 cm^{-1}$. Description: Author Institution: Herzberg Institute of Astrophysics, National Research Council of Canada URI: http://hdl.handle.net/1811/9735 Other Identifiers: 1976-RN-3