Collisional excitation transfer between Na and Na2

Abstract

We have excited Na(3s) →Na(3p) with a pulsed dye laser at Na densities of 1014–1016 cm−3 with typically ∼2% Na2. From the decay time constants, intensities and spectra of the Na and Na2 fluorescences we have identified several collisional and radiative processes in the excited sodium atom-dimer system. Comparing the solutions of coupled equations to the density dependence of the decay constants and fluorescence intensities yields a rate coefficient of (3.4+1.6−1.1) ×10−9 cm3 sec−1 for the excitation transfer process: Na* (3p)+Na2(X 1Σ) →Na(3s) +Na2* (A 1Σ and a 3Π). This indicates that some kind of long-range interaction is operative. Other rate coefficients are determined less accurately; e.g., nonradiative Na(3p) quenching rate coefficients of 10±5×10−10 cm3 sec−1 due to dimer collisions and of 3±3×10−12 cm3 sec−1 due to atom collisions are obtained.