VIBRATIONAL STATE CONTROLLED BOND-CLEAVAGE IN THE PHOTODISSOCIATION OF ISOCYANIC ACID (HNCO)

被引：64

作者：

BROWN, SS

BERGHOUT, HL

CRIM, FF

机构：

[1] Department of Chemistry, University of Wisconsin-Madison, Madison

来源：

JOURNAL OF CHEMICAL PHYSICS | 1995年 / 102卷 / 21期

关键词：

D O I：

10.1063/1.468835

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

We report the bond selected photodissociation of isocyanic acid (HNCO). This molecule dissociates from its first excited singlet state, breaking either the N-H bond to form H + NCO (X 2Π) or the C-N bond to form NH (a 1Δ) + CO (1Σ+). The threshold for production of NH lies about 3900 cm-1 above that of NCO, and we detect both of these channels by laser induced fluorescence on either the NH or the NCO fragment. Dissociating the molecule out of a vibrationally excited state on its ground electronic surface containing four quanta of N-H stretch (4v 1) enhances the efficiency of the NCO channel over the NH channel by a factor of at least 20. We reach this conclusion by comparing the results of such a vibrationally mediated photodissociation experiment to those from a conventional single photon dissociation at the same total energy (about 1000 cm-1 above the threshold for the NH channel). Our estimate of the branching ratio in the one photon dissociation at this energy is roughly ΦNCO/ΦNH≈20, and it grows to ΦNCO/ΦNH≥400 in the vibrationally mediated photodissociation. © 1995 American Institute of Physics.

引用

页码：8440 / 8447

页数：8

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