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Dimers of acetic acid in helium nanodroplets

Davies, Julia A.; Hanson-Heine, Magnus W. D.; Besley, Nicholas A.; Shirley, Andrew; Trowers, James; Yang, Shengfu; Ellis, Andrew M.


Julia A. Davies

Magnus W. D. Hanson-Heine

Nicholas A. Besley

Andrew Shirley

James Trowers

Shengfu Yang

Andrew M. Ellis


The structural arrangement of small carboxylic acid molecules in the liquid phase remains a controversial topic. Some studies indicate a dominance of the cyclic dimer that prevails in the gas phase, whilst other studies favor short fragments of the infinite catemer chains that are found in the crystalline phase. Furthermore, difficulties in preparing and probing size-selected catemer segments have resulted in a lack of benchmark data upon which theoretical models of the condensed phases can be built. To address these issues, we have combined infrared spectroscopy and quantum chemical calculations to explore regions of the intermolecular potential energy surface associated with the formation of metastable dimer isomers. The OH stretching region of the spectrum shows that aggregation of acetic acid molecules inside liquid helium nanodroplets yields two distinct metastable dimers, whilst negligible signal is observed from the cyclic dimer that typically overwhelms this spectral region. We deduce that the most abundant isomer in superfluid helium has one strong O−H···O=C and one weak C−H···O=C hydrogen bond. Since this bonding motif is common to the dimeric repeating unit of the catemer, it is of fundamental importance for understanding intermolecular interactions in the condensed phases of small carboxylic acids.

Journal Article Type Article
Publication Date Oct 29, 2018
Journal Physical Chemistry Chemical Physics
Print ISSN 1463-9076
Electronic ISSN 1463-9084
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Keywords Physical and theoretical chemistry; General physics and astronomy
Publisher URL!divAbstract
Additional Information


This file is under embargo until Oct 29, 2019 due to copyright restrictions.

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