Fourier transform emission spectrum of the HCSi radical, (A)over-tilde 2Σ+-(X)over-tilde 2Πi transition

A Fourier transform emission spectrum of the HCSi, (A) over tilde (2)Sigma(+)-(X) over tilde (2)Pi(i) transition was observed by means of a Schuler-type discharge tube in the 9000-14 000 cm(-1) spectral region. Three bands whose origins appeared at 12 934.406, 11 766.721, and 10 752.430 cm(-1) were rotationally analyzed and assigned, respectively, to the (100)-(000), (000)-(000), and (000)-(100) bands. The new ab initio calculated A((X) over tilde (2)Pi) spin-orbit constant agrees well with the experimental value. Weak rotational perturbations in the (100) level of the upper electronic state are likely due to highly excited vibrational levels of the ground state, whereas the "anomalous" increase of the spin-rotation constant in the (100) level of the ground state relative to the (000) level was shown to result of a Fermi interaction with the (020) (2)Pi Renner-Teller components. A comparison was made between the rotational constants of the (000) ground state level with those obtained in concomitant works. (C) 2000 American Institute of Physics. [S0021-9606(00)01124-7].