  Spectral characterization of Super-Earth atmospheres for planets orbiting in
the Habitable Zone of M-dwarf stars is a key focus in exoplanet science. A
central challenge is to understand and predict the expected spectral signals of
atmospheric biosignatures (species associated with life). Our work applies a
global-mean radiative-convective-photochemical column model assuming a planet
with an Earth-like biomass and planetary development. We investigated planets
with gravities of 1g and 3g and a surface pressure of one bar around central
stars with spectral classes from M0 to M7. The spectral signals of the
calculated planetary scenarios have been presented by Rauer et al. (2011). The
main motivation of the present work is to perform a deeper analysis of the
chemical processes in the planetary atmospheres. We apply a diagnostic tool,
the Pathway Analysis Program, to shed light on the photochemical pathways that
form and destroy biosignature species. Ozone is a potential biosignature for
complex- life. An important result of our analysis is a shift in the ozone
photochemistry from mainly Chapman production (which dominates in the
terrestrial stratosphere) to smog-dominated ozone production for planets in the
Habitable Zone of cooler (M5-M7)-class dwarf stars. This result is associated
with a lower energy flux in the UVB wavelength range from the central star,
hence slower planetary atmospheric photolysis of molecular oxygen, which slows
the Chapman ozone production.
