STATE-TO-STATE COLLISIONAL QUENCHING OF VIBRATIONALLY EXCITED NO+(UPSILON) IONS

Vibrational relaxation of NO+(v=1,2,3) in collisions with a broad rang e of neutral species has been examined. REMPI is used to form state-se lected NO+(v), and a monitor ion technique is used to state selectivel y follow the changes in vibrational level induced by collision. The NO +(v) ions are generated in the reaction cell of an FT-ICR spectrometer which is then used to measure the parent ion and monitor ion signals. The NO+(v=1) quenching rate constants for collision with Ar, Kr, Xe, N2, CO2, CS2, CH4, CF4, CHF3, CH3F, CH3Cl, CH3Br, C2H4, C3H8, and NO v ary from less than or similar to 0.4 X 10(-10)(Ar)to 13 X 10(-10) cm3/ s (C3H8). The corresponding values for 2NO+(v=3) are all higher. The q uenching systems studied all follow a DELTAv=-1 selection rule. Possib le correlations between quenching efficiency and the physical properti es of the quencher are discussed in context with the collision dynamic s.