Nascent Rotational Distribution of CO2(0000, J) States from Collisions with Highly Vibrationally Excited Na2

Abstract

In this work, the high vibrational states of Na₂ were excited via stimulated emission pumping. The full-state resolution distribution of molecular scattering of CO₂(00⁰0, J), resulting from collisions with excited Na₂ X¹ Σ⁺_g (v''= 33 and 45), was also investigated. In particular, the scattered CO₂(00⁰⁰, J = 2–80) molecules were found to possess a biexponential rotational distribution. The low- and high-energy distributions were derived by fitting the data by means of a biexponential model. The cold distribution accounted for 80% of the total scattering and was caused by elastic or weakly inelastic collisions. Such collisions might have caused very small rotational excitations in CO₂. The hot distribution involved substantial changes in the rotational energy of CO₂ and accounted for 20% of the total amount of collisions. The influence of the donor energy on the rotational distribution was shown to be very large; however, for the two types of donor energies, the branches associated with inelastic and elastic collision rates were the same. The nascent translational energy curves for scattered CO₂(00⁰0, J = 56–80) were measured via high-resolution transient overtone fluorescence. For every 25% enhancement in donor vibrational energy, the product translational energy of an individual J-state increased by 60%. Additionally, the measured collision rates were found to be weakly dependent on the donor energy.