High-resolution Fourier transform spectroscopy of the CaO A(1)Sigma(+)-X-1 Sigma(+) transition: New insights into perturbations by the a(3)Pi(0+) and A(1)Pi states

A van Groenendael, M Tudorie, C Focsa, B Pinchemel, P F Bernath

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The emission spectrum of the A(1)Sigma(+) - X(1)Sigma(+) transition of CaO has been recorded at a resolution of 0.03 cm(-1) using a Fourier transform spectrometer in the 10000-15000 cm(-1) spectral range. New information has been collected for the low-J term values of several vibrational levels of the A(1)Sigma(+) state and also for the perturbing states. For example, about 40 term values of a(3)Pi(0)+ (v = 6) level [which perturbs the A(1)Sigma(+)(v = 0) level] have been identified for the first time. A least squares procedure has been used to determine the vibrational and rotational constants of these states. In each case an empirical 2 x 2 matrix has been used with an off-diagonal term linking the two electronic states to account for the interaction. Our study is limited to perturbations for which extensive experimental information is available for both interacting states. The derived constants, especially the off-diagonal coupling constants, are in agreement with those published by R.W. Field [J. Chem. Phys. 60 (1974) 2400-2413]. (c) 2005 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)255-263
Number of pages9
Issue number2
Publication statusPublished - Dec 2005


  • high-resolution Fourier transform spectroscopy
  • perturbations
  • calcium oxide diatomic molecule
  • A'(1)PI-X-1-SIGMA(+) SYSTEM
  • SRO
  • BAO

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