Near infrared absorptions of neon, argon, krypton, and xenon excited diatomic molecules

Abstract

Two types of transient absorptions due to excited diatomic molecules have been observed for neon, argon, and krypton irradiated with electron beam pulses in following wavelength regions: 8000 to 8200 Å and 9000 to 10 300 Å for neon, 9500 to 10 000 Å and 11 400 to 13 000 Å for argon, and 9500 to 10 000 Å and 11 600 to 14 000 Å for krypton. The first absorptions located at shorter wavelengths consist of several discrete bands and their lifetimes are longer than those of the second absorptions located at longer wavelengths. In addition, the intensities of the second absorptions are much weaker than those of the first absorptions. We have failed to observe the second absorption of xenon, which may be located at longer wavelengths than the observation limit. The time-dependent changes of absorption spectra suggest the formation of vibrationally and rotationally excited molecules. We attribute the lower state of the first absorption to the lowest triplet state 1 u(3∑u+) and the upper one to the state 3Πg resulting from a combination of a ground state atom p0(1S0) and any of low-lying Paschen 2p excited atoms. The lower state of the second absorption is attributed tentatively to the lowest excited singlet state Ou+ ( 1∑u+), while the upper state may be to 1Πg or 3∑Zg+. © 1978 American Institute of Physics.