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Using surface science techniques to investigate the interaction of acetonitrile with dust grain analogue surfaces

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posted on 2023-06-10, 00:23 authored by Emily Rose Ingman, Amber ShepherdAmber Shepherd, Wendy BrownWendy Brown
Surface science methodologies, such as reflection-absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD), are ideally suited to studying the interaction of molecules with model astrophysical surfaces. Here we describe the use of RAIRS and TPD to investigate the adsorption, interactions and thermal processing of acetonitrile and water containing model ices grown under astrophysical conditions on a graphitic dust grain analogue surface. Experiments show that acetonitrile physisorbs on the graphitic surface at all exposures. At the lowest coverages, repulsions between the molecules lead to a decreasing desorption energy with increasing coverage. Analysis of TPD data gives monolayer desorption energies ranging from 28.8 - 39.2 kJ mol-1 and an average multilayer desorption energy of 43.8 kJ mol-1. When acetonitrile is adsorbed in the presence of water ice, the desorption energy of monolayer acetonitrile shows evidence of desorption with a wide range of energies. An estimate of the desorption energy of acetonitrile from CI shows that it is increased to ~37 kJ mol-1 at the lowest exposures of acetonitrile. Amorphous water ice also traps acetonitrile on the graphite surface past its natural desorption temperature, leading to volcano and co-desorption. RAIRS data show that the C=N vibration shifts, indicative of an interaction between the acetonitrile and the water ice surface.

History

Publication status

  • Published

File Version

  • Published version

Journal

Johnson Matthey Technology Review

ISSN

2056-5135

Publisher

Johnson Matthey

Department affiliated with

  • Chemistry Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2021-07-16

First Open Access (FOA) Date

2023-02-03

First Compliant Deposit (FCD) Date

2023-02-03

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