Unraveling the Rich Fragmentation Dynamics Associated with S–H Bond Fission Following Photoexcitation of H2S at Wavelengths ~129.1 nm

H2S is being detected in the atmospheres of ever more interstellar bodies, and photolysis is an important mechanism by which it is processed. Here, we report H Rydberg atom time-of-flight measurements following the excitation of H2S molecules to selected rotational (JKaKc') levels of the 1B1Rydberg state associated with the strong absorption feature at wavelengths of ? ~ 129.1 nm. Analysis of the total kinetic energy release spectra derived from these data reveals that all levels predissociate to yield H atoms in conjunction with both SH(A) and SH(X) partners and that the primary SH(A)/SH(X) product branching ratio increases steeply with ?Jb2?, the square of the rotational angular momentum about the b-inertial axis in the excited state. These products arise viacompeting homogeneous (vibronic) and heterogeneous (Coriolis-induced) predissociation pathways that involve coupling to dissociative potential energy surfaces (PES(s)) of, respectively, 1A? and 1A' symmetries. The present data also show H + SH(A) product formation when exciting the JKaKc' = 000and 111levels, for which ?Jb2? = 0 and Coriolis coupling to the 1A' PES(s) is symmetry forbidden, implying the operation of another, hitherto unrecognized, route to forming H + SH(A) products following excitation of H2S at energies above ~9 eV. These data can be expected to stimulate future ab initiomolecular dynamic studies that test, refine, and define the currently inferred predissociation pathways available to photoexcited H2S molecules.