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The adsorption and desorption of ethanol ices from a model grain surface
journal contribution
posted on 2023-06-08, 17:18 authored by D J Burke, A J Wolff, J L Edridge, Wendy BrownWendy BrownReflection absorption infrared spectroscopy (RAIRS) and temperature programed desorption (TPD) have been used to probe the adsorption and desorption of ethanol on highly ordered pyrolytic graphite (HOPG) at 98 K. RAIR spectra for ethanol show that it forms physisorbed multilayers on the surface at 98 K. Annealing multilayer ethanol ices (exposures > 50 L) beyond 120 K gives rise to a change in morphology before crystallization within the ice occurs. TPD shows that ethanol adsorbs and desorbs molecularly on the HOPG surface and shows four different species in desorption. At low coverage, desorption of monolayer ethanol is observed and is described by first-order kinetics. With increasing coverage, a second TPD peak is observed at a lower temperature, which is assigned to an ethanol bilayer. When the coverage is further increased, a second multilayer, less strongly bound to the underlying ethanol ice film, is observed. This peak dominates the TPD spectra with increasing coverage and is characterized by fractional-order kinetics and a desorption energy of 56.3 +/- 1.7 kJ mol(-1). At exposures exceeding 50 L, formation of crystalline ethanol is also observed as a high temperature shoulder on the TPD spectrum at 160 K. (c) 2008 American Institute of Physics.
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Journal of Chemical PhysicsISSN
0021-9606Publisher
American Institute of PhysicsExternal DOI
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10Volume
128Department affiliated with
- Chemistry Publications
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- Yes
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2014-07-23First Open Access (FOA) Date
2014-07-23First Compliant Deposit (FCD) Date
2014-07-23Usage metrics
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