The Laser Induced Fluorescence Spectrum of Te₂Studied by Fourier Transform Spectrometry

Laser induced fluorescence spectra of separated isotope tellurium dimers, 130 Te 2 and 128 Te 2 , have been recorded with high precision Fourier transform spectrometry. Fixed frequency argon ion and krypton ion exciting lines ranging from 5145 Å to 4067 Å have been used and 64 series in 130 Te 2 and 32 in 128 Te 2 have been assigned and analyzed. Transitions involving four upper states, A 0 u + , B 0 u + and two states of 1 u character, and three lower states, X 0 g + , X 1 g and b 1 Σ g + , have been identified. The high sensitivity and excellent frequency calibration of Fourier transform spectrometry have been used to get information about high vibrational levels in the lower states and thence to derive, by simultaneous least squares fits to about 7800 lines in 130 Te 2 and 1100 lines in 128 Te 2 , estimates of molecular constants valid over wide ranges of v . These have been used to determine RKR potentials and dissociation energies. The very small Ω-doubling constant in X 1 g has been measured and is shown to have the value expected for interaction solely with X 0 g + . The character of the states is discussed. There are many perturbations, and intensity distributions show that some transitions are hybrids with parallel and perpendicular components. A 0 u + appears to derive from 3 Π u and B 0 u + from 3 Σ u - , while the lowest 1 u state may be assigned to 3 Π 1, u . There is fragmentary evidence for a second 1 u state in the same region. Among the low lying states of Te 2 , a 1 Δ g remains to be observed.