Borengasser Q, Hager T, Kanaherarachchi A, Troya D, Broderick BM. Conformer-Specific Desorption in Propanol Ices Probed by Chirped-Pulse Millimeter-Wave Rotational Spectroscopy.
J Phys Chem Lett 2023:6550-6555. [PMID:
37450900 DOI:
10.1021/acs.jpclett.3c01468]
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Abstract
We present a new technique for the detection of molecules desorbed from an ice surface using broad-band millimeter-wave rotational spectroscopy. The approach permits interrogation of molecules that have undergone the slow warmup process of temperature-programmed desorption (TPD), analogous to the warmup phase of icy grains in the interstellar medium as they approach the central protostar. The detection is conformer- and isomer-specific and quantitative, as afforded by chirped-pulse rotational spectroscopy. To achieve this, we combine ice TPD with buffer gas cooling, followed by detection in the millimeter-wave regime. In this report we examine the TPD profiles of n- and i-propanol, the former of which may be in five different conformational isomeric forms, and which display distinct desorption profiles. The limited conformational isomerization and temperature-dependent relative yields of n-propanol conformers observed show that the desorption is highly conformer-specific.
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