Laser Fluorescence and Mass Spectrometric Measurements of Vibrational Relaxationof N2(+)(v) with He, Ne, Ar, Kr, and Xe

摘要

The vibrational relaxation of N2(+)(v) is studied at thermal energies for therare gas collision partners, He, Ne, Ar, Kr and Xe. The selected ion flow tube-laser-induced fluorescence technique is combined with conventional mass spectrometry to measure accurately the extremely small rate constants for vibrational relaxation with these rare gas atoms. Measured rate constants for N2(+)(v=1) are 9.8(plus or minus 0.7) x 10(exp -16) cu cm/molecule/s for He, 3.6(plus or minus 0.5) x 10 (exp -14) for Ne, <1.2 x 10(exp -11) for Ar, <2 x 10(exp -12) for Kr, and 1.6(plus or minus 0.2) x 10(exp -13) for Xe. For Ne, laser fluorescence is used to probe the individual levels, N2(+)(v 1-4). The small deactivation probabilities, ranging from 1.7 x 10(exp -6) for He to 1.6 x 10(exp-4) for Xe, are discussed in terms of two types of relaxation mechanisms. The correlation between the rare gas polarizability and the relaxation rate constant strongly suggests the importance of attractive forces in the vibrational relaxation. A direct impulsive mechanism may be operative for the vibrational relaxation of N2(+)(v) with He. p4.