The role of the pre-exponential factor on temperature programmed desorption spectra : A computational study of frozen species on interstellar icy grain mantles
Pantaleone, Stefano (Università degli Studi di Torino. Dipartimento di Chimica)
Tinacci, Lorenzo (Università degli Studi di Torino. Dipartimento di Chimica)
Bariosco, Vittorio (Universitat Autònoma de Barcelona. Departament de Química)
Rimola, Albert (Universitat Autònoma de Barcelona. Departament de Química)
Ceccarelli, Cecilia (Centre National de la Recherche Scientifique. Université Grenoble Alpes)
Ugliengo, Piero (Università degli Studi di Torino. Dipartimento di Chimica)

Date:	2025
Abstract:	Temperature programmed desorption (TPD) is a well-known technique to study gas-surface processes, and it is characterized by two main quantities: the adsorbate binding energy and the pre-exponential factor. While the former has been well addressed in recent years by both experimental and computational methods, the latter remains somewhat ill-defined, and different schemes have been proposed in the literature for its evaluation. In the astrochemistry context, binding energies and pre-exponential factors are key parameters that enter microkinetic models for studying the evolution over time of the chemical species in the universe. In this paper, we studied, by computer simulations, the effect of different pre-exponential factor models using water, ammonia, and methanol adsorbed on amorphous and crystalline ices as test cases: specifically, the one most widely used by the astrochemical community (Herbst-Hasegawa), the models provided by Tait and Campbell, and an extension of the Tait formulation including the calculation of the vibrational partition function. We suggest the methods proposed by Tait and Campbell that provide TPD temperature peaks within 30 K of each other while avoiding demanding quantum mechanical calculations, as they are based on tabulated data. Finally, when the explicit inclusion of the vibrational partition function is needed, we propose a cost-effective strategy to include all the thermal contributions in the partition functions without the need for performing a full vibrational calculation of the whole system.
Grants:	European Commission 741002 European Commission 865657 European Commission 811312
Note:	Altres ajuts: 2023 ICREA Award
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Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Astrochemistry ; Campbell ; Computational studies ; Desorption spectra ; Energy ; ITS evaluation ; Partition functions ; Preexponential factor ; Surface process ; Temperature-programmed desorptions
Published in:	Journal of chemical physics, Vol. 163, Num. 4 (July 2025) , art. 044117, ISSN 1089-7690

DOI: 10.1063/5.0266978

Available from: 2026-07-31 15 p, 6.4 MB

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