Rotational level dependent quenching of the A 3Πi, v′=0 state of NH

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Abstract
Quenching cross sections σQ have been measured for several rotational levels N’ in the A 3∏i, v’=0 state of NH, for a variety of collision partners. Ground state NH was generated in a room temperature discharge flow and excited with a pulsed laser, and the time decay of fluorescence was measured. The radiative lifetime for the levels N’=1 to 5 is 418 ± 8 ns. The σQ’s are generally large, up to 90 Å2, and decrease with increasing N’. This indicates the influence of an anisotropic, attractive interaction in most but not all cases. The present values of σQ are compared with those of other experiments; because σQ depends both on N’ and collision energy, experimental conditions must be carefully specified to yield results which are readily comparable.