A Fibre-Coupled UHV-Compatible Variable Angle Reflection-Absorption UV/Visible Spectrometer

James W. Stubbing, Tara L. Salter, Wendy A. Brown, Skandar Taj, Martin R. S. McCoustra

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Abstract

We present a novel UV/visible reflection-absorption spectrometer for determining the refractive index, n, and thicknesses, d, of ice films. Knowledge of the refractive index of these films is of particular relevance to the astrochemical community, where they can be used to model radiative transfer and spectra of various regions of space. In order to make these models more accurate, values of n need to be recorded under astronomically relevant conditions, that is, under ultra-high vacuum (UHV) and cryogenic cooling. Several design considerations were taken into account to allow UHV compatibility
combined with ease of use. The key design feature is a stainless steel rhombus coupled to an external z-shift allowing a variable reflection geometry to be achieved, which is necessary for our analysis. Test data for amorphous benzene ice is presented as a proof of concept, the film thickness, d, was found to vary linearly with surface exposure and a value for n of 1.43 ± 0.07 was determined.
Original languageEnglish
Article number054102
JournalReview of Scientific Instruments
Volume89
Issue number5
DOIs
Publication statusPublished - May 2018

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