IMPROVED SOURCE OF NF(B1-SIGMA+) MOLECULES - SPECTROSCOPIC CONSTANTS AND EVIDENCE FOR E-V ENERGY-TRANSFER REACTIONS WITH CH4 AND H2O

A low-power dc discharge in a dilute flow of NF2 in Ar carrier gas provides a source of NF(b) molecules in the concentration range (2-5) x 10(11) molecules cm-3, which is 20-50 times larger than the concentration from the reaction of Ar(3P0,2) with NF2 for the same conditions in the flow reactor. The discharge source gives high vibration levels, upsilon' less-than-or-equal-to 11, and the NF(b1-SIGMA+ --> X3-SIGMA-) spectrum had strong bands for the DELTA-upsilon = +/- 2 sequences. The extended spectrum from high-upsilon' levels provides improved vibrational constants, omega"e = 1136.7 +/- 3.3 and omega"ex"e = 8.9 +/- 0.9 cm-1; omega'e = 1191.1 +/- 3.7 and omega'ex'e = 8.2 +/- 1.0 cm-1. The dependence of the NF(b --> X) transition dipole upon the rBAR centroid was assigned as -5.4075 + 9.0695rBAR - 3.2183r2BAR for 1.0 less-than-or-equal-to rBAR less-than-or-equal-to 1.8 angstrom. The direct observation of NF(a1-DELTA) formation from the quenching of NF(b1-SIGMA+) by CH4 and H2O proved that E-V energy transfer is the major channel for NF(b) deactivation. The E-V quenching data are consistent with the accepted radiative lifetime of NF(a).