Electron excitation of the resonance lines of the alkali-metal atoms

Abstract

%'e have measured the relative optical-excitation functions and polarizations of the K, Rb, and Cs resonance lines, using crossed electron and atom beams, for electron energies from threshold to 1500 eV.The electron energy resolution was -0.25 eV for energies below 13 eV, and the atom-beam was optically .thin. The atomic resonance-level (n P) excitation functions have been normalized to the Born theory in the high-energy limit. Comparisons are made with other measurements and calculations. The polarizations and total cross sections for H, Li, Na, K, Rb, and Cs are also compared with each other in reduced units to investigate systematic behavior

Measurement of the absolute total electron impact cross section on Cs atoms using a magnetooptical trap

“…Extrapolation of the theoretical results reported by Burke and Mitchell [11] and Karule and Peterkop [10] to high energies shows that our results are likely to support their theory. We are in agreement with the results of Chen and Gallagher [19] and McFarland and Kinney [20] beyond 100 eV, who carried out measurements on the electron-impact cross sections in our working energy range using other techniques. We also confirm the recent experimental and theoretical results of MacAskill et al [16] and Lukomski et al [17].…”

“…Recent theoretical results using the CCC scheme reported by MacAskill et al [16] and Lukomski et al [17] covering our energy range, others in the low-energy range reported earlier by Karule and Peterkop [10], Burke and Mitchell [11], and the experimental results reported by Visconti et al [7], Jaduszliwer and Chan [8], Chen and Gallagher [19] and McFarland and Kinney [20], are shown in Fig. 4.…”

A collisional radiative model for low-pressure hydrogen–caesium plasmas and its application to an RF source for negative hydrogen ions

“…2 for excitation from 6 2 S to the first excited state 6 2 P. Several of the theoretical cross sections are based on the Born or the Bethe method. In [37] it was shown that close to the threshold energy excitation cross sections calculated by these methods are generally by a factor of two to three higher compared to measured values -indicating a large error bar of the calculations in this energy range. Suggested in [37] is the following simple empirical formula for correcting such cross sections for alkali metals in the lowenergy region close to the threshold:…”

“…Available in the literature is a multitude of theoretically [35,[46][47][48][49]36,[50][51][52] and experimentally determined [37,[53][54][55]] electron collision excitation cross sections for caesium. CsðiÞþe À -Cs þ þ 2e À [38] Recombination of Cs þ Cs þ þ 2e À -CsðjÞþe À [38], Saha equation…”

Coherence and Correlation in Electron Scattering from the Alkalis

“…4a shows considerably more structure than was the case for lithium and reflects the increase in size of the potassium atom. In this case the angular distribution was integrated using Simpson's rule and normalised to an interpolated integral cross section for the excitation of the 4 2 P state of Chen and Gallagher (1978).…”