Special Paper Infrared Spectra and Radiation Stability of H2O2 Ices Relevant to Europa

In this paper we present spectra of H2O2-containing ices in the near- and mid-infrared (IR) regions. Spectral changes on warming are shown, as is a comparison of near-IR bands of H2O and H2O2-containing ices. An estimate of the A-value (absolute intensity) for the largest near-IR feature of H2O2 is given. Radiation-decay half-lives are reported for 19 K and 80 K, and are related to the surface radiation doses on Europa. The radiation data show that H2O2 de-struction is slower at 80 K than 19 K, and are consistent with the claim that icy material in the outermost micrometer of Europa’s surface has been heavily processed by radiation. Key Words: Europa—Hydrogen peroxide—Radiation effects—Infrared spectra. Astrobiology 6