Rovibrational Intensities of the Minor Isotopes of the CO \\ $X\ ^{1} \Sigma^{+}$\ State for $v \leq$\ 20 and $J \leq$\ 150

Previous abstract Next abstract

Session 112 -- Models and Synthetic Spectroscopy
Display presentation, Saturday, January 15, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[112.02] Rovibrational Intensities of the Minor Isotopes of the CO \\ $X\ ^{1} \Sigma^{+}$\ State for $v \leq$\ 20 and $J \leq$\ 150

D. Goorvitch, C. Chackerian, Jr. (NASA/ARC)


Electric dipole transition matrix elements for rovibrational transitions in the ground state $X\ ^{1} \Sigma^{+}$\ of the CO minor isotopes \CO46\ and \CO37\ are calculated for the first time for all the $\Delta v$\ = +1, +2, and +3 transitions for which $v \leq$\ 20 and $J \leq$\ 150. Improved electric dipole transition matrix elements are also calculated for the minor isotopes \CO27, \CO28, and \CO38. These results for the minor species of CO complement those previously reported by us [Goorvitch and Chackerian, ApJS, 1993, in press ] for \CO26\ and \CO36. We have used the electric dipole moment function (EDMF) from Chackerian et al. [Can. J. Phys. , 62 , 1579, 1984] and the numerical wavefunctions calculated by the method of Goorvitch and Galant [ JQSRT , 47 , 391, 1992] to calculate the rovibrational transition moments. These calculated transition moments combined with highly accurate term values and transition frequencies reported by Farrenq et al. [J. Molec. Spectrosc. , 149 , 375, 1991] for \CO27\ and \CO28\ and by Guelachvili et al. [J. Molec. Spectrosc. , 98 , 64, 1983] for \CO38, \CO37, and \CO46, or the mass--independent Dunham parameters of Authier et al. [J. Molec. Spectrosc. , 160 , 590, 1993] allow the calculation of the Einstein A values, $gf$\ values, and the temperature dependent line strengths. The matrix element of the transition moments are given as a polynomial expansion in terms of the parameter $m \equiv [J'(J'+1) - J''(J''+1)] / 2$. The maximum degree for each of the polynomial fits is derived using orthogonal polynomials which are tested for statistical significance. The EDMF used reproduces all the known intensity data on $X\ ^{1} \Sigma^{+}$\ CO including the permanent electric moment. Hure and Roueff [J. Molec. Spectrosc. , 160 , 335, 1993] calculated intensities for CO using an ab initio EDMF which has a permanent moment which is about a factor of three too large. We have pointed out, Chackerian and Goorvitch [J. Molec. Spectrosc. , submitted, 1993], that this discrepancy causes a very large overestimation of the effects of the vibration--rotation interaction on the calculated intensities.

Saturday program listing