Rates of collision-induced emission from metastable O(1S) atoms

Abstract

The radiative decay of metastable 1 s 22s '2p 4 ISO atomic oxygen atoms has been shown to proceed at a rate depending linearly on the concentration of argon or xenon present in the gas mixture. With increasing pressure, the IDrISo atomic line at 5577 A becomes accompanied by a broad emission region identified as a band system of a weakly bound rare-gas oxide molecule. Changes in the transition probability as a function of pressure were measured by using the spin-forbidden ) P I_I So transition at 2972 A as a pressure-independent monitor of the 0(' S) concentration. The observed pressure dependence of the emission probability may be described by rate constants for induced emission in argon and xenon atmospheres: (1) for emission in a bandwidth of + 1.6 A centered on the atomic line at 5577 A, k(Ar)=(7±3)XIO-20 em) seC I, k(Xe)=(3±2)XIO-I9 cm 3 sec-I ;and (2) for emission into the entire green band system, k(Ar)=(3.0+.2)XIO-I8 em) sec-I, k(Xe)=(1.7±.2)x 10-15 em) sec-I. Comparison is made with rate constants for deactivation of these metastable atoms by the same rare gases. It appears that substantially all of the collision-induced emission comes from bound rare-gas oxide molecules whose dissociation equilibria provide the observed pressure dependence.

Theoretical feasibility study of new high-efficiency continuous-wave lasers operating at electron transitions in the spectral regions from near ir to uv on the basis of unconventional mechanisms of forming the active gaseous media

“…As a result, the Ar~ complexes, whose emission induces the photolysis of N20 with formation of O(1S), were formed; it was established that ,-~75% of absorbed photons were involved in the formation of these excited atoms. Under a pressure of 50 atm, the lifetime of ArO was found to be 1.6 9 10 -4 s, which is consistent with the rate constant for reaction (6.14) as derived in [91]; at the same time, the decay of 1D state occurs, in ~10 -9 s. The gain in the transition 1E+ __~1 E + (lII), as estimated in [93], amounts to ~10 -3 cm 1. Subsequently, on the basis of the same concepts, the same authors achieved lasing at wavelengths close to the green line of oxygen [94].…”

“…In [90], the emission related to the 1S __+1 D transitions in oxygen atoms was studied in the case of high nitrogen pressure. Quantitative results were reported in [91]; the values of K(Ar) = 3 9 10 -18 cma/s and K(Xe) = 1.7-10 -15 cm3/s were obtained for the rate constants of process (6.14). In addition, in [91], the data reported in [90] were used to find that K(N2) --1.2.10 -is cm3/s.…”

“…Quantitative results were reported in [91]; the values of K(Ar) = 3 9 10 -18 cma/s and K(Xe) = 1.7-10 -15 cm3/s were obtained for the rate constants of process (6.14). In addition, in [91], the data reported in [90] were used to find that K(N2) --1.2.10 -is cm3/s. The deactivation rates of O(1S) in a number of gases (At, Kr, Xe, Ne, N2, and H2) measured in [92] could also be related to the collision-stimulated emission.…”

“…There are a number of experimental studies (see, for example, [85][86][87][88][89][90][91]) where the aforementioned phe- where Q is a particle stimulating the emission in the collision. It was established [87,89] that there is no molecule-related emission in the helium medium, whereas, in argon and krypton, ArO and KrO molecules emit only in the region of 557.7 nm [88].…”

O(1S → 1D,3P) branching ratio as measured in the terrestrial nightglow

“…The most obvious issues are wavelength calibration and pressure-induced emission. It has long been known that the 557.7 nm line is pressure-sensitive [Black et al, 1975], whereas the 297.2 nm line is not [Cunningham and Clark, 1974], leading to an overestimation of R if the pressure is too high. In each of the three laboratory experiments, tests were applied to show that for the given conditions, the green line intensity did not increase with pressure.…”