The Application of Ultraviolet/Visible Spectroscopy to the Study of Surface Astrochemistry James W. Stubbing, Tara L. Salter, Wendy A. Brown, Skandar Taj and Martin R. S. McCoustra

Introduction Simulate conditions of the ISM T ≈ 24 K p ≤ 2.0 × 10-10 mbar Adsorb molecules onto surfaces HOPG Silica Interstellar processing of ices Thermal Bombardment Irradiation Spectroscopically RAIRS

New UV/vis Setup

Determine values of n and k Why? Determine values of n and k

How? Determined values of n and k iterate Fit using Fresnel equations and Kramers-Kronig relation Compare simulated spectrum to experiment Measure reflectance Model R’ Determined values of n and k θ, ν, d R R’ θ, ν, d θ, ν, d R θ, ν, d iterate