13C16O2: Global Treatment of Vibrational–Rotational Spectra and First Observation of the 2ν1 + 5ν3 and ν1 + 2ν2 + 5ν3 Absorption Bands

Spectroscopy and Intensity Measurements of the 3ν1+3ν3 Tetrad of 12CO2 and 13CO2

“…Three of the four components of the extremely weak 3ν 1 + 3ν 3 tetrad could be detected in a spectral region where absorption due to atmospheric water was strongly dominant. The experimental wavenumbers are found to be in very good agreement both with the predictions of the recently developed EH (4,6) and with variational calculations (15). The corresponding absolute band intensities have been measured.…”

“…We give also in Table 3 the range of the difference of the observed wavenumbers from their values predicted by the effective Hamiltonian approach (4,6). Excellent agreement is achieved in particular for the 12 CO 2 species, which show deviations limited to 0.02 cm −1 , further demonstrating the excellent predictive abilities of the effective Hamiltonian developed in Ref.…”

“…Note. The total fraction is slightly less than 1 as a consequence of extremely weak mixing with other vibrational states (6).…”

“…As mentioned above, the (30 0 3) vibrational state is expected to carry most of the intensity strength of the 3ν 1 +3ν 3 tetrad. The decomposition of the eigenstates in the zeroth-order normal mode basis, as predicted by the effective Hamiltonian (4,6), is presented in Tables 5 and 6 for 12 CO 2 and 13 CO 2 , respectively (5). It is then interesting to compare the measured relative intensities to the fraction of the (30 0 3) state in the eigenstate decomposition.…”

“…(4) and Ref. (6) for 12 CO 2 and 13 CO 2 , respectively. For symmetry reasons, the considered transitions correspond to an odd quantum number of the antisymmetric stretch, ν 3 .…”