An elusive species with many different traits (English shop)

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In the scope of this thesis different traits of the elusive species HSOH have
been examined. HSOH, either known as oxadisulfane or hydrogen thio-
peroxide is the link between the well known molecules HSSH, disulfane, and
HOOH, hydrogen peroxide. HSOH is not only interesting because of its rele-
vance in the combustion theory of sulfur, the sulfur cycle in the atmosphere,
or as possible constituent in the interstellar medium but also because of its
substantially spectroscopical importance.
With two different rotor moieties, SH and OH, HSOH represents the most
general case of a four-atomic, internally rotating chain molecule. In order
to provide further improvement of the theoretical understanding of internal
rotation earlier experimental studies by Winnewisser et al.1 have been ex-
tended into the THz-region.
The first gas-phase detection of the singly deuterated oxadisulfane HSOD
presented here provided the last piece of the puzzle to determine a semi-
experimental equilibrium structure of HSOH.
In order to get information on the dynamics involved in the molecule, the
measurements have been extended into the infrared region and both high fre-
quency bond stretching modes vOH = 1 and vSH = 1 have been assigned. The
analysis of the bands proves HSOH to be a fairly rigid “textbook” molecule
in case of the OH-stretching mode, while the vSH = 1 state shows a strong
potential coupling to some dark state.
Last but not least, it turned out that HSOH exhibits an anomalous intensity
pattern for rotational transitions involving Ka > 3 states. Even though this
effect is not reported yet it seems to be not a special trait of HSOH, but
rather a spectroscopic effect of general importance.