The near ultraviolet photolysis of H2S has been investigated further,
at nine different excitation wavelengths in the range 244-198 nm and a
t yet higher resolution than hitherto, using the technique of H (Rydbe
rg) atom photofragment translational spectroscopy. Analyses of the tot
al kinetic energy release spectra of the primary H + SH fragments has
allowed further refinement of the parent bond dissociation energy, D-0
(0)(HS-H) = 31 440 +/- 20 cm(-1), and revealed a marked correlation be
tween the wavelength dependence of [f(vib)], the fraction of the avail
able energy partitioned into SH(X) product vibration, and the first of
the diffuse vibronic structures evident in the UV absorption spectrum
of the H2S parent. Secondary photolysis of the primary SH(X) fragment
s has also been investigated further. 2 + 1 Resonance enhanced multiph
oton ionization spectroscopy has been used to confirm that the S(P-3)
atoms resulting from 218.2 nm photolysis of the primary SH(X) fragment
s are formed in all three spin-orbit states, with a near statistical (
i.e. 2J'' + 1) population distribution. Such a finding is fully consis
tent with our modelling of the shape of the structureless early time f
eature in the H atom time-of-flight spectrum, which arises as a result
of this secondary photolysis process. This modelling also serves to c
onfirm the correctness of our previous determination of the S-H bond s
trength in the mercapto radical: D-0(0)(S-H) = 29 300 +/- 100 cm(-1).