Atomic oxygen recombination at surface defects on reconstructed (0001) α-Quartz exposed to atomic and molecular oxygen

Ruben Meana Paneda, Yuliya Paukku, Kaining Duanmu, Paul Norman, Thomas E Schwartzentruber, Donald G Truhlar

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The surface chemistry of silica is strongly affected by the nature of chemically active sites (or defects) occurring on the surface. Here, we employ quantum mechanical electronic structure calculations to study an uncoordinated silicon defect, a non-bridging oxygen defect, and a peroxyl defect on the reconstructed (0001) surface of α-quartz. We characterized the spin states and energies of the defects, and calculated the reaction profiles for atomic oxygen recombination at the defects. We elucidated the diradical character by analyzing the low-lying excited states using multireference wave function methods. We show that the diradical defects consist of weakly coupled doublet radicals, and the atomic oxygen recombination can take place through a barrierless process at defects. We have delineated the recombination mechanism and computed the formation energy of the peroxyl and non-bridging oxygen defects. We found that key recombination reaction paths are barrierless. In addition, we characterize the electronically excited states that may play a role in the chemical and physical processes that occur during recombination on these surface defect sites.

Original languageEnglish (US)
Pages (from-to)9287-9301
Number of pages15
JournalJournal of Physical Chemistry C
Volume119
Issue number17
DOIs
StatePublished - Apr 30 2015

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