The Low-Lying States of He2.
The near-infrared emission spectrum of He2, excited in a Be hollow cathode discharge, has been recorded at high resolution using a Fourier transform spectrometer. The c3Sigma+<INF POS="STACK">g-a3Sigma+<INF POS="STACK">u (0-0, 1-1, 2-2, 1-0, and 2-1) and C1Sigma+<INF POS="STACK">g-A1Sigma+<INF POS="STACK">u (0-0 and 1-1) transitions have been observed in the 9000-15 000 cm-1 spectral region. A global analysis of the six lowest excited states of He2 (c3Sigma+<INF POS="STACK">g, b3Pig, a3Sigma+<INF POS="STACK">u, C1Sigma+<INF POS="STACK">g, B1Pig, and A1Sigma+<INF POS="STACK">u) was carried out by combining our measurements with previously reported infrared data for the b3Pig-a3Sigma+<INF POS="STACK">u system [S. A. Rogers et al., Mol. Phys. 63, 901 (1988)] and with laser measurements for the B1Pig-A1Sigma+<INF POS="STACK">u transition [H. Solka et al., Mol. Phys. 60, 1179 (1987)]. To account for the fine structure in the a3Sigma+<INF POS="STACK">u state, high precision r.f. measurements were included in the global fit. A consistent set of improved molecular constants was derived for the c3Sigma+<INF POS="STACK">g (v = 0, 1, and 2), b3Pig (v = 0 and 1), a3Sigma+<INF POS="STACK">u (v = 0, 1, and 2), C1Sigma+<INF POS="STACK">g (v = 0 and 1), B1Pig (v = 0 and 1), and A1Sigma+<INF POS="STACK">u (v = 0 and 1) levels. A study of the vibrational dependence of these constants was also performed, leading to the equilibrium parameters for the six electronic states. Copyright 1998 Academic Press.
Laboratoire de Chimie Physique Moléculaire, UniversitéLibre de Bruxelles, C.P. 160/09, 50 av. F. D. Roosevelt, Brussels, 1050, Belgium
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Focsa
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