Measurements of electron-impact ionization cross sections of neon by comparison with photoionization

Abstract

A method and apparatus have been developed for precise measurements of the ratios of total cross sections for electron-impact ionization and photoionization in rare gases based on the comparison of the total ion yields of the two ionization processes. Low uncertainties for the cross-section ratios are achieved above all by using a cryogenic electrical substitution radiometer as a primary detector standard in the soft-x-ray and vacuum ultraviolet spectral ranges in order to determine the impinging photon flux. On the basis of our measured cross-section ratios and well-known total photoionization cross sections we deduce absolute total electronimpact ionization cross sections of rare gases. As a result we present ratios of total electron-impact ionization cross sections to total photoionization cross sections and deduce total electron-impact ionization cross sections of neon in the energy range of electrons from 140 to 4000 eV and of photons from 100 to 1500 eV. Relative uncertainties as low as 1.3% for the cross-section ratios and 2.8% for the total electron-impact ionization cross sections have been achieved. A comparison of our cross-section data with published experimental and theoretical data is presented.

Local Epitaxial Growth of (103) One-Axis-Oriented SrBi2Ta2O9 Thin Films Prepared at Low Deposition Temperature by Metalorganic Chemical Vapor Deposition and Their Electrical Properties

“…In figure 2, the results are illustrated using the experimental results for H (Jones et al 1993), He and Ar (Moxom et al 1996), Ne, Kr and Xe (Kara et al 1997). The uncertainties concerning the absolute magnitude of the ionization cross sections of the inert gases by positron-and electron-impact (see Van Reeth et al 2002, Sorokin et al 1998 are irrelevant to the present discussion as the data are scaled to their peak value. Ne, Ar, Kr and Xe have the same general shape 3 whilst He and H data are found to be narrower and shifted towards lower values of E/E th .…”

Gas detectors for x-ray lasers

“…The values represent a compilation of the experimental data given in Refs. [18][19][20][21][22][23][24][25][26][27][28] keV. To further increase the detector sensitivity, the X-GMD has the option to collect photoions created over the comparably large distance of 20 cm along the photon beam by means of an additional extraction field maintained by an aperture system ͑see Fig.…”

Measurement of the density profile of pure and seeded molecular beams by femtosecond ion imaging

“…25 All these effects would exhibit a nonlinear dependence on the Xe gas pressure. Figure 3 shows the measured ion count as a function of the bulk gas pressure, ranging between 3.2 × 10 −5 millibars and 1.6 × 10 −4 millibars (uncorrected pressure readings).…”