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Surface three-dimensional velocity map imaging: A new technique for the study of photodesorption dynamics

  • The authors describe the application of a combination of velocity map imaging and time-of-flight (TOF) techniques to obtain three-dimensional velocity distributions for surface photodesorption. They have established a systematic alignment procedure to achieve correct and reproducible experimental conditions. It includes four steps: (1) optimization of the velocity map imaging ion optics’ voltages to achieve optimum velocity map imaging conditions; (2) alignment of the surface normal with the symmetry axis (ion flight axis) of the ion optics; (3) determination of TOF distance between the surface and the ionizing laser beam; (4) alignment of the position of the ionizing laser beam with respect to the ion optics. They applied this set of alignment procedures and then measured Br(²P₃/₂) (Br) and Br(²P₁/₂) (Br∗) atoms photodesorbing from a single crystal of KBr after exposure to 193 nm light. They analyzed the velocity flux and energy flux distributions for motion normal to the surface. The Br∗ normal energy distribution shows two clearly resolved peaks at approximately 0.017 and 0.39 eV, respectively. The former is slightly faster than expected for thermal desorption at the surface temperature and the latter is hyperthermal. The Br normal energy distribution shows a single broad peak that is likely composed of two hyperthermal components. The capability that surface three-dimensional velocity map imaging provides for measuring state-specific velocity distributions in all three dimensions separately and simultaneously for the products of surface photodesorption or surface reactions holds great promise to contribute to our understanding of these processes.

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    This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Vacuum Science & Technology A 28, 807 (2010) and may be found at https://doi.org/10.1116/1.3327929.

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Author:Yuanyuan Ji, Sven P. K. KöhlerORCiD, Daniel J. AuerbachORCiD, Alec M. WodtkeORCiD
DOI original:https://doi.org/10.1116/1.3327929
Parent Title (English):Journal of Vacuum Science & Technology A
Publisher:AIP Publishing
Document Type:Article
Year of Completion:2010
Publishing Institution:Hochschule Hannover
Release Date:2022/06/22
GND Keyword:Bilderzeugung; Photodesorption; Flugzeitspektrometrie
First Page:807
Last Page:813
Link to catalogue:1809957613
Institutes:Fakultät II - Maschinenbau und Bioverfahrenstechnik
DDC classes:620 Ingenieurwissenschaften und Maschinenbau
Licence (German):License LogoUrheberrechtlich geschützt