Lifetimes of Metastable CO andN2Molecules

Abstract

The average lifetime of metastable CO molecules in the a II state excited by electron impact at 7. 5 eV at room temperature was found to be about 1 msec. Lifetimes of metastable N2 molecules in the a'0~and E Z~s tates were found to be 115+20 and 190 +30 @sec, respectively. There was evidence for at least one higher-lying metastable state of CO at about 10eV having a lifetime of about 0. 1 msec. The lifetimes were obtained in a time-of-flight experiment and deduced from the measurements without resorting to analytic expressions of the time-of-flight distribution.The observed time-of-Qight distributions were essentially Maxwellian. A diffuse-gas source operated at pressures in the 10 4-Torr range was used. Effects due to metastable recoil, uv photons from metastable decay, and metastable wall collisions were carefully examined and found to be negligible under most conditions. Metastable excitation functions were obtained using a low-energy high-resolution electron gun.

Valence–Rydberg electronic states of N2: spectroscopy and spin–orbit couplings

“…This assignment was definitely confirmed later theoretically and experimentally [34,35,[38][39][40][41]. Our calculations show that the 1 3 Σ g -is lying closely to the E state.…”

Electron impact excitation functions of radiating and metastable states of carbon monoxide

“…Therefore, in this work, the two-cycle RPD operation of the gun was eliminated and only the first cycle of the pulsing scheme pre- UCRL-20905 Figure 1 shows the excitation f'unctionformetastable states produced by electron impact on CO. The excitation threshold was found to be 5.9 eV as compared to the spectroscopic value of 6.01 eVe All curves recorded in this study showed the same steady rise to a plateau at approximately 10 eVe A reproducible feature was the small increase in signal near 13 eVe The shape of the curve agrees quite well with the initial portion of a metastable CO curve recently published by Borst and Zipf [3]. It is, however, quite different from the curve measured by Olmsted, Newton, and street [6].…”

A predissociative triplet Rydberg state of the nitrogen molecule studied by near-infrared diode laser kinetic spectroscopy

“…The lowest Rydberg state with gerade symmetry is characterized by a long lifetime. The lifetime of the E 3 R g state with the electronic configuration of (N 2 + :X 2 R core)(3sr g ) was reported to be 190 ls [1]. These metastable nitrogen molecules play a very important role not only in the chemistry of high-temperature flames but also in the photochemistry of the upper stratosphere.…”