Probing the interaction between solid benzene and water using vacuum ultraviolet and infrared spectroscopy

Dawes, Anita; Pascual, Natalia; Mason, Nigel J.; Gärtner, Sabrina; Hoffmann, Søren V. and Jones, Nykola C. (2018). Probing the interaction between solid benzene and water using vacuum ultraviolet and infrared spectroscopy. Physical Chemistry Chemical Physics, 20 pp. 15273–15287.

DOI: https://doi.org/10.1039/C8CP01228H

Abstract

We present results of a combined vacuum ultravioloet (VUV) and infrared (IR) photoabsorption study of amorphous benzene:water mixtures and layers to investigate the benzene-water interaction in the solid phase. UV spectra of 1:1, 1:10 and 1:100 benzene:water mixtures at 24 K reveal a concentration dependent shift in the energies of the ¹B_2u, ¹B_1u and ¹E_1u electronic states of benzene. All the electronic bands blueshift from pure amorphous benzene towards gas phase energies with increasing water concentration. IR results reveal a strong dOH-π benzene-water interaction via the dangling OH stretch of water with the delocalised π system of the benzene molecule. Although this interaction influences the electronic states of benzene with the benzenewater interaction causing a redshift in the electronic states from that of the free benzene molecule, the benzene-benzene interaction has a more significant effect on the electronic states of benzene. VUV spectra of benzene and water layers show evidence of non-wetting between benzene and water, characterised by Rayleigh scattering tails at wavelengths greater than 220 nm. Our results also show evidence of benzene-water interaction at the benzene-water interface affecting both the benzene and the water electronic states. Annealing the mixtures and layers of benzene and water show that benzene remains trapped within in/under water ice until water desorption near 160 K. These first systematic studies of binary amorphous mixtures in the VUV, supported with complementary IR studies, provide a deeper insight into the influence of intermolecular interactions on intramolecular electronic states with significant implications for our understanding of photochemical processes in more realistic astrochemical environments.

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About

• Item ORO ID
• 55092
• Item Type
• Journal Item
• ISSN
• 1463-9076
• Project Funding Details

• Funded Project Name	Project ID	Funding Body
  Not Set	Not Set	The Open University (OU)
  Not Set	Not Set	Daphne Jackson Trust
  Not Set	Not Set	STFC (Science & Technology Facilities Council)
  Not Set	Not Set	The Leverhulme Trust
  CALIPSO Infrastructure Programme	Not Set	European Community

• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
  Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Research Group
• Astronomy
  Physics
• Copyright Holders
• © 2018 Royal Society of Chemistry
• Depositing User
• Anita Dawes