Low-lying singlet excited states of isocyanogen

Document Type

Article

Abstract

Recent photofragment fluorescence excitation (PHOFEX) spectroscopy experiments have observed the à 1A″ singlet excited state of isocyanogen (CNCN) for the first time. The observed spectrum is not completely assigned and significant questions remain about the excited states of this system. To provide insight into the energetically accessible excited states of CNCN, optimized geometries, harmonic vibrational frequencies, and excitation energies for the first three singlet excited states are determined using equation-of-motion coupled-cluster theory with singles and doubles (EOM-CCSD) and correlation-consistent basis sets. Additionally, excited state coupled-cluster methods which approximate the contributions from triples (CC3) are utilized to estimate the effect of higher-order correlation on the energy of each excited state. For the à 1A″ state, our best estimate for T0 is about 42,200 cm-1, in agreement with the experimentally estimated upper limit for the zero-point level of 42,523 cm-1. © 2008 Wiley Periodicals, Inc.

Department(s)

Chemistry

Publication Title

International Journal of Quantum Chemistry

Volume

108

Issue

6

First Page

1137

Last Page

1140

Publication Date

12-1-2007

DOI

10.1002/qua.21586

ISSN

00207608

E-ISSN

1097461X

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