Wavelength dependence of the photoelectron angular distributions of the rare gases

Abstract

Photoelectron angular distributions for the valence p shells of the rare gases have been measured up to a photon energy of 40.8 eV (48.4 eV for Ne) using resonance radiation from a hollow-cathode discharge lamp. This work extends the range of existing absolute measurements on Ne, Kr, and Xe. Comparison with Hartree-Fock and RPAE (random-phase approximation with exchange) calculations indicates excellent agreement for Ne. However, the present results, particularly for Xe, add to earlier evidence that data for Ar, Kr, and Xe show systematic deviations from theory, especially at the higher photoelectron kinetic energies. For Kr and Xe, we report asymmetry parameters separately for processes leading to the 'P3/2 $/2 spin-orbit states of the residual ion. The Xe results indicate that P3/2 Pi/2 is positive for 'A )461 A, but changes sign in the range X -350 -400 A. At 304 A, p3/,pl/, ---0.30, which agrees with a recent calculation based on the Dirac-Slater model.

Experimental determination of the phase differences of continuum wavefunctions describing the photoionisation process of xenon atoms. I. Measurements of the spin polarisations of photoelectrons and their comparison with theoretical results

“…In order to check whether residual fields had been sufficiently suppressed, a great number of asymmetry parameters p have been measured at different photon energies using a third resonance lamp placed at an angle of 8 = 16" (not shown in figure 2). The agreement of the /3 values measured for several noble gases and molecules (Schonhense 1978) with those found by other authors (Dehmer et al 1975, Miller et al 1977, Niehaus and Ruf 1972 confirmed the reliability of the angle-resolved spin-polarisation measurements. For these measurements the photoelectrons were observed at angles f 8 , with respect to the two light beams, where 8, is the magic angle, 54" 44', so-called because at this angle Q(8) = Q/47r in equation (1) and the parameter 5 in equation (2) can be obtained without any knowledge of p. 5 is then found from 5 = 1.…”

Experimental characterization of the Xe 5p photoionization by angle- and spin-resolved photoelectron spectroscopy

“…Excellent data exist for the asymmetry parameter fl, which has been measured at resonance wavelengths of discharge sources [25,[98][99][100][101][102][103][104][105][106][107] as well as with synchrotron radiation [87-89, 108, 109]. In addition to the spin-parameters A, e and ~ measured with circularly polarized synchrotron radiation, 4-values from experiments with unpolarized line radiation [23,26] were used (at the HeI (21.22eV) and NeIb (16.85 eV) resonance lines).…”

Dipole and nondipole photoionization of molecular hydrogen

“…(38) and (39) and measuring photoelectron intensities from transitions of known β e values. The He 1s β e = 2 at photon energies below the doubly excited states near ∼60 eV, and the Ne 2p β e vs energy is accurately known through measurements and theory [56][57][58][59][60][61]. Measurements of He 1s and Ne 2p photoelectrons were used to determine s 0 /s ⊥ = 1.1-1.2 over the 5-to 130-eV kinetic energy range.…”