Unveiling the surface structure of amorphous solid water via selective infrared irradiation of OH stretching modes

J. A. Noble, C. Martin, H. J. Fraser, P. Roubin, S. Coussan

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

In the quest to understand the formation of the building blocks of life, amorphous solid water (ASW) is one of the most widely studied molecular systems. Indeed, ASW is ubiquitous in the cold interstellar medium (ISM), where ASW-coated dust grains provide a catalytic surface for solid phase chemistry, and is believed to be present in the Earth's atmosphere at high altitudes. It has been shown that the ice surface adsorbs small molecules such as CO, N 2, or CH4, most likely at OH groups dangling from the surface. Our study presents completely new insights concerning the behavior of ASW upon selective infrared (IR) irradiation of its dangling modes. When irradiated, these surface H2O molecules reorganize, predominantly forming a stabilized monomer-like water mode on the ice surface. We show that we systematically provoke "hole-burning" effects (or net loss of oscillators) at the wavelength of irradiation and reproduce the same absorbed water monomer on the ASW surface. Our study suggests that all dangling modes share one common channel of vibrational relaxation; the ice remains amorphous but with a reduced range of binding sites, and thus an altered catalytic capacity.

Original languageEnglish
Pages (from-to)826-829
Number of pages4
JournalJournal of Physical Chemistry Letters
Volume5
Issue number5
DOIs
StatePublished - Mar 6 2014
Externally publishedYes

Keywords

  • ASW
  • IR selective irradiation
  • amorphous ice
  • dangling bonds
  • interstellar medium

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