Spontaneous lifetimes and relaxation cross-sections of the D1Π state of NaRb

The time-resolved intensity of dispersed laser induced fluorescence following the Ar+-laser D1Π←X1Σ+ excitation was measured for both 23Na85Rb and 23Na87Rb isotopomers in a thermal cell. Spontaneous radiative lifetime values determined for v′(J′) rovibronic levels of the D1Π state in the v′ range from 0 to 17 and J′ from 8 to 131 varied from 22.5 to 17.3 ns. Averaged collisional quenching cross-section values of (3–6)×10−14 cm2 were obtained for NaRb (D1Π,v′,J′) + Rb collisions from the Stern–Volmer plots.