Optical-optical double resonance probe of the dark state of thiophosgene in supersonic free jet

One-photon excitation of the S-0 ((X) over tilde) thiophosgene to the S-1 ((A) over tilde) state, followed by photodepletion of the S-1 -->S-0 fluorescence by Sn (n = 2, 3) <-- S-1 excitation, by another photon, reveals the presence of a dark S-3 ((C) over tilde) state in the vicinity of the (B) over tilde (1)A(1) (pipi*), S-2, state. The measured polarization and the vibrational structure of the (C) over tilde <-- (A) over tilde absorption are consistent with the (C) over tilde state being the B-1(2) (nsigma*) state, predicted by the CASSCF calculations of Strickler and Gruebele [Chem. Phys. Lett. 349 (2001) 1371]. The dominant decay channel of the (C) over tilde B-1(2)(nsigma*) state is shown to be the direct internal conversion to the (X) over tilde (1)A(1) state. (C) 2004 Elsevier B.V. All rights reserved.