  We develop a new 1D photochemical kinetics code to address stratospheric
chemistry and stratospheric heating in hot Jupiters. Here we address optically
active S-containing species and CO2 at 1200 < T < 2000 K. HS (mercapto) and S2
are highly reactive species that are generated photochemically and
thermochemically from H2S with peak abundances between 1-10 mbar. S2 absorbs UV
between 240 and 340 nm and is optically thick for metallicities [SH] > 0 at T >
1200 K. HS is probably more important than S2, as it is generally more abundant
than S2 under hot Jupiter conditions and it absorbs at somewhat redder
wavelengths. We use molecular theory to compute an HS absorption spectrum from
sparse available data and find that HS should absorb strongly between 300 and
460 nm, with absorption at the longer wavelengths being temperature sensitive.
When the two absorbers are combined, radiative heating (per kg of gas) peaks at
100 microbars, with a total stratospheric heating of about 8 x 10^4 W/m^2 for a
jovian planet orbiting a solar-twin at 0.032 AU. Total heating is insensitive
to metallicity. The CO2 mixing ratio is a well-behaved quadratic function of
metallicity, ranging from 1.6 x 10^-8 to 1.6 x 10^-4 for -0.3 < [M/H] < 1.7.
CO2 is insensitive to insolation, vertical mixing, temperature (1200 < T <2000
K), and gravity. The photochemical calculations confirm that CO2 should prove a
useful probe of planetary metallicity.
