Precision spectroscopy and comprehensive analysis of perturbations in the A\,1(v=0) state of 13C 18O
Abstract
We have reinvestigated the A1(v=0) level of 13C18O\ using new high-resolution spectra obtained via multi-photon laser excitation as well as with synchrotron-based Fourier-transform absorption spectroscopy of the A1 -X1+(0, 0), e3--X1+(1, 0), d3-X1+(4, 0), a'3+-X1+(9, 0), and (11, 0) bands. In addition, Fourier-transform emission spectroscopy in the visible range is performed on the B1+- A1(0, 0) band. Spectra of the (0, 0) band are measured in order to tie information from the latter emission data to the level structure of A1(v=0). The high pressures in the absorption cell at the synchrotron and the high temperatures in the emission discharge permitted monitoring of high rotational quantum levels in A1(v=0) up to J=43. All information, in total over 900 spectral lines, was included in an effective-Hamiltonian analysis of the A1(v=0, J) levels that are directly perturbed by the e\,3-(v=1), d3\!(v=4), a'3+(v=9), d3\!(v=0), I\,1-(v=0, 1) close-lying levels and the e\,3-(v=0,2), d3\!(v=3,5), a'3+(v=8,10) remote levels, as well being indirectly influenced by the a3(v=10, 11) state. The influence of nine further perturber levels and their interactions was investigated and are not significant for reproducing the present experimental data. This analysis leads to a much improved description in terms of molecular constants and interaction parameters, compared to previous studies of the same energy region for other CO isotopologues.