Normalized, absolute di6'erential cross sections (DCS's) have been measured for the 20 lowest electronic states of xenon. Incident electron energies were 15, 20, 30, and 80 eV and the scattering angles ranged from 5 to 150. The energy resolution was 40 meV. Absolute elastic DCS's have been obtained by normalizing the relative values to the recently published absolute elastic DCS's by Register et ai. [J. Phys. B 19, 1685[J. Phys. B 19, (1986]. Elastic-to-inelastic intensity ratios, at different incident energies for the 6s [ -], state were determined. These ratios were utilized as secondary standards to establish the absolute scale for the other inelastic processes in accordance with intensity ratios of lines in energy-loss spectra. The absolute inelastic DCS's were extrapolated to 0' and 180' and integrated to yield the integral cross sections (ICS's). A comparison of the present DCS's with the only available measurements at 20 eV impact energy shows satisfactory agreement in shape but considerable difFerence in absolute value.

We determined experimentally two critical points in elastic electron scattering by argon where the differential cross section (DCS) attains its smallest values. The points were found to be at 68.5 • ± 0.3 • , 41.30 ± 0.02 eV and at 143.5 • ± 0.3 • , 37.30 ± 0.02 eV. Special attention was given to improve the angular resolution in order to determine the exact positions of the minima. These minima are important because they are a sensitive test of the validity of experimental procedures, and are used to verify theoretical predictions of DCS shapes and magnitudes, and of the polarization of scattered electrons. Normalized DCS were determined by measuring the angular distributions of elastically scattered electrons at incident energies of 10, 15, 20, 25, 30, 40, 50, 60, 75, 80, 90 and 100 eV in the angular range 20 • -150 • . Results are compared with the available experimental and theoretical data. In addition, integral, momentumtransfer, and viscosity cross sections were determined by numerical integration of the measured DCS extrapolated to 0 • and to 180 • .

The experimental and theoretical studies of elastic electron scattering by calcium atom have been made. The experimental investigation was carried out using a crossed electron-atom beam technique. The measurements were performed at electron-impact energies (E0) of 10, 20, 40, 60 and 100 eV and for a range of scattering angles (θ) from 10° up to 150°. The absolute differential cross sections (DCSs) have been obtained from the elastic-to-inelastic (the resonant 41P0 state) intensity ratio at θ = 10° at each E0. Calculations have been performed in the optical potential approximation for the same E0 and θ between 0° and 180°. Results for DCSs and integrated (integral, momentum transfer and viscosity) cross sections are presented and compared with those predicted by existing calculations.

Relative differential electron impact cross sections sigma ( theta ) for elastic and inelastic scattering in mercury have been measured. The sigma ( theta ) are normalized to the optical oscillator strength for the 61S0-61P1 transition and put on an absolute scale. Results are presented at 15, 25, 35, 40, 50, 60 and 100 eV for elastic scattering and the 61P1 excitation. In addition the 63P1, 71S0 and 71P1 excitation sigma ( theta ) are presented at 60 eV. The angular ranges are from 2' for inelastic and from 10' for elastic scattering, up to 150'. Results are compared with the other experimental and theoretical data. Comparison with the relativistic calculations is given by Srivastava et al. in the following paper (ibid., vol.26, no.5, p.1025-30 (1993)).

Relative elastic scattering and excitation cross sections of cadmium, up to the first ionization potential, are obtained from spectroscopic measurements on electrons with initial energies ranging from 3.4 to 85 eV. Relative differential cross sections in the angular range of 0" to 15O'arc reponed for excitation of the S'S, (elastic),