Laboratory investigations of benzene on surfaces of astrophysical relevance
Carbon in the Universe
Tara L Salter
University of Sussex
James W Stubbing (University of Sussex), Wendy A Brown (University of Sussex)
Polycyclic aromatic hydrocarbons (PAHs) are thought to be present throughout the interstellar medium and account for around 20% of the galactic carbon. They have been proposed as the carriers of the diffuse interstellar bands (DIBs) and the unidentified infrared bands (UIRs). Here we present a laboratory investigation of the simplest building block of PAHs, benzene, in astrophysically relevant ices. Using an ultra-high vacuum chamber (at a pressure of 10^(-10) mbar) with a base temperature of 25 K, we are able to simulate the conditions of interstellar space. Molecular ices of benzene and water are grown upon highly oriented pyrolytic graphite, a carbonaceous dust grain analogue surface. We use temperature programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS) to investigate the interactions between benzene and water. We are able to probe the bonding and trapping of benzene in the presence of water ices. Parameters including desorption energy have been calculated from data analysis of TPD traces. We can incorporate these parameters into astrophysical models using interstellar heating rates to understand the implications of our work for interstellar chemistry.


09:00 - 10:30
EX - C33 (150)