On theJ-dependence of the odd (ns′,J=0,1) autoionization resonances of the rare gases Ne, Ar, Kr, and Xe

Abstract

Using resonant two-photon ionization of metastable rare gas atoms Rg(mp 5(m + 1)s 3P2,0) in a collimated beam by two transverse cw dye lasers, we have performed a comprehensive high resolution study of the odd Rg(ns',J =0,1) autoionization resonances of all the heavier rare gases Rg--Ne, Ar, Kr and Xe. In this way, we have determined the variation of the nearly n-independent reduced resonance widths F, = n*3. Fn (n*= effective quantum number) with atomic size andfor the first time -with the angular momentum J for all Rg. The reduced widths for the Rg(ns', J = 1) resonances vary by about a factor of three, being lowest for Ne(371 cm -1) and largest for Kr(l185 cm-1). Compared to J = 1, the Rg(ns', J =0) resonances are three times narrower for Ne, but up to two times broader for Ar, Kr, and Xe. The results of ab initio calculations for the widths are reported, in which the relevant transition matrix elements are carefully evaluated. Good overall agreement of the calculated widths with the experimental data is achieved. For Rg(ns', J = 0), the first order s'-d coupling amplitude provides a satisfactory description only for Rg = Ne, whereas for Rg = Ar-Xe, correlation effects are important. For Rg(ns', J = 1), the additional amplitudes due to s'-d exchange coupling and due to s'-s decay are found to be of varying importance with atomic number. Destructive interference between the different amplitudes and the influence of Rg(ns', J = i)-Rg(nd', J --t) coupling are responsible for the fact that the (ns', J = 1) resonances are narrower than the (ns', J = 0) resonances for Ar, Kr, and Xe.

Experimental and theoretical cross sections for photoionization of metastable Xe*. (6s 3 P 2, 3 P 0) atoms near threshold

“…in ionization potential and chemical interactions. The open shell nature of the Rg + [(m − 1)p 5 ] ion core leads, however, to specific properties of the rare gases such as series of prominent autoionization resonances between the two lowest ionization potentials 2 P 3/2 − 2 P 1/2 [1][2][3][4][5] and the presence of substantial admixture of d-valence character [6][7][8][9][10][11][12][13], which is especially strong for the Xe * (5p 5 6s J = 0) metastable level due to the proximity to the Xe * (5p 5 5dJ = 0) level [9][10][11][12][13]. The latter effects and the influence of electron correlations associated with virtual excitations of the core electrons [14][15][16][17][18][19] lead to the one photon excitation of nf Rydberg states besides np states and, On leave from: Rostov State University of Transport Communications, Rostov-on-Don, Russia correspondingly, cause the appearance of εf partial photoelectron waves besides εp waves in electric dipole single photoionization of Rg * , as described by the reactions:…”

Laser photoionization of metastable Xe* (J=0) atoms in the range 462–430 nm

“…In the measurements of the wavelength dependent cross sections the ion or angle-differential electron rates were sampled simultaneously with the laser intensity, the transmission fringes of a Fabry-Perot etalon (free spectral range 199.4 GHz) and the flux of metastable atoms. Relative cross sections were derived from these raw data in the way described previously [19,20,36].…”

A facility for the analysis of the electronic structures of solids and their surfaces by synchrotron radiation photoelectron spectroscopy

“…The beamline resolution is regularly verified at two photon energies by measuring the Fano-type resonances in photoionization spectra of He near 60 eV 16 and Ne gas near 20 eV. 18,19 The pressure of the gas is set to approximately 5 · 10 −2 mbar as measured on a Pirani vacuum gauge, and the photocurrent is picked up by a blank copper wire running parallel to the beam. The gas cell volume is isolated from the ultrahigh vacuum (UHV) of the beamline by a 150 nm thin Al membrane, that is transparent for photon energies between 20 and 70 eV.…”