ROVIBRATIONAL EXCITATION OF CARBON-MONOXIDE BY ENERGY-TRANSFER FROM METASTABLE NITROGEN

The CO fundamental vibration-rotation spectra resulting from the interaction of discharged nitrogen with carbon monoxide at low pressure (∼3 mTorr) exhibit bimodal rotational distributions. We have identified 14 vibrational levels of a rotationally relaxed (80 K) component and eight vibrational levels from a rotationally excited component. The eight rotationally excited bands are best reproduced by a statistical distribution E=E R+EV=3.7 eV, which provides sufficient population in the region of the Fortrat reversal (J∼90) to account for the observed R-branch bandhead formation. The rotationally relaxed vibrational levels are populated by single- and two-quantum transfer from N2(v), N2(v) + CO→N2(v-1,2) + CO(v=1,2), and radiative cascade from CO(A) produced by quenching of N2(α′), N 2(α′ 1Σu-) + CO→N2(X,v) + CO(A 1Π)→CO(v≤9) + hv, and relaxation of the rotationally excited component. Kinetic and energetic arguments indicate that a branch of N2(α′) quenching N2(α′ 1Σu-) + CO→N2(X,v) + CO(v≤14,J) is responsible for the rotationally excited component. Surprisal analysis indicates two dynamic mechanisms are responsible for the rotationally excited component. We have modeled the vibrational distribution of the rotationally excited component with equal contributions from a statistical (all v) process and a process favoring excitation of low vibrational levels (v≤4). © 1990 American Institute of Physics.