Emission spectroscopy of jet-cooled CS2 upon excitation of the 1Σg+→1B2(1Σu+) transition in the 48 500-51 000 cm-1 region

The jet-cooled emission spectroscopy of gaseous carbon disulfide (CS2) was performed in the 48500-51000 cm(-1) region in order to investigate changes in the early time dynamics of CS2 in the predissociative B-1(2) ((1)Sigma(u)(+)) state. The spectra show emission into progressions of both the symmetric stretching (v(1)) and bending (v(2)) motions and combinations bands of these two motions. Analysis shows that the contribution of symmetric stretching and bending motion varies over the range of excitation wavelengths and the progression of v(2) decreases in intensity relative to the progression in v(1) as one scans through the energetic region near the barrier to linearity of this bent excited state molecule. We estimate the barrier height to be approximately 3400 cm(-1) above the zero-point level of the B-1(2) ((1)Sigma(u)(+)) state. (C) 1998 American Institute of Physics. [S0021-9606(98)00542-X].