Intramultiplet energy transfer in the collisions of 3p 4D nitrogen atoms with nitrogen molecules

Two-photon excitation at 211 nm combined with wavelength-resolved detection near 870 nm is used to study intramultiplet energy transfer in the 2s22p23p 4D0 state of nitrogen atoms resulting from collisions with nitrogen molecules. The thermally averaged cross sections at 300 K vary from 36±10 Å2 for 4D01/2→4D03/2 to 3±3 Å2 for 4D07/2→4D01/2. The cross sections for ΔJ=1 are larger than for ΔJ=2 which in turn are larger than for ΔJ=3. When 3p4D07/2 is excited with linearly polarized light, the fluorescence polarization is nonzero and independent of N2 pressure. Thus, the cross section for transfer between magnetic sublevels is smaller than those for transfer out of that fine-structure level.