Luminescence of gases excited by high-energy radiation. Part 1.—Collisional deactivation in nitrogen

Abstract

When nitrogen and nitrogen+oxygen mixtures, in the pressure range 1-750 mm Hg are excited by soft X-rays, the strongest emission features in the visible and ultra-violet spectrum are the second positive bands (C3nU-B3ng of N2) and first negative bands (B2';st-X2Zg of N ; ) . Intensity measurements show that the NZ B state is deactivated in approximately every collision with ground-state nitrogen and oxygen molecules, if normal gas-kinetic cross-sections are assumed ; this is also true of the N2 C state in collision with oxygen, while the cross-sections for deactivation by nitrogen are about one-thirtieth and onetenth of the gas-kinetic cross-section, for v' = 0 and 1 respectively.

Air fluorescence relevant for cosmic-ray detection—Review of pioneering measurements

“…In 1964, Brocklehurst published quenching parameters for nitrogen-nitrogen and nitrogen-oxygen collisional de-excitation [4]. To this end, he measured the light emission in pure nitrogen gas and in nitrogen-oxygen mixtures within a pressure range of 1 to 750 mm Hg.…”

“…For studying the kinetics of collisional processes, the pressure was chosen to be higher than 1 mm Hg, since above this value the excitation conditions are independent of pressure [4]. It is mentioned that secondary electrons cause excitation above 10 −2 mm Hg, but are completely absorbed in the gas for pressure higher than 1 mm Hg.…”

“…Furthermore, the excitation is assumed to be without ion recombination processes. Former measurements are cited in the publication by Brocklehurst [4] showing that fields applied for the removal of ions do not have any effect on the light output. An iterative procedure was applied in the analysis of the quenching parameters for separating between 1 N and 2 P states of nitrogen.…”

“…The de-excitation process was subdivided by Bunner into three parts: radiative transition to any lower state, collisional quenching, and internal quenching with the corresponding life times τ v , τ c , and τ i . In further considerations, Bunner did not differentiate between the first and last de-excitation channel anymore and introduced the nomenclature of 4 1…”

“…The mean zero-pressure intercept yielded (60.4 ±0.4) nsec. The lifetimes for the second positive system of nitrogen states were investigated using the 3805Å (0,2), 4059Å (0,3), 3755Å (1,3), 3998Å (1,4), and the 3711Å (2,4) transitions. The mean lifetime for v ′ = 0 was determined to be (40.4 ± 0.5) nsec, for v ′ = 1 to (40.6 ±0.5) nsec, and for v ′ = 2 to (38.5 ±0.6) nsec.…”