Elastic electron scattering from water vapor and ice at high momentum transfer.

We compare the area, peak separation, and width of the H and O elastic peak for light and heavy water, as observed in spectra of keV electrons scattered over large angles. Peak separation is well reproduced by the theory, but the O:H area ratio is somewhat larger than expected and is equal to the O:D area ratio. Thus no anomalous scattering from H was observed.

Fully differential molecular-frame measurements for the electron-impact dissociative ionization of H2.

We present fully differential state-resolved experimental data for the dissociative ionization of molecular hydrogen induced through electron impact. Molecular-frame ionization cross sections are derived for transitions from the X{1}Sigma{g}{+} molecular ground state to the 1ssigma{g}, 2psigma{u}, 2ssigma{g}, and 2ppi{u} states of H2+. For transitions to the 2ssigma{g} and 2ppi{u} states, a strong orientation dependence in the cross sections is revealed, with "side-on" preferred to "end-on" collisions and a propensity for the fragment proton to emerge along the normal to the scattering plane.

Electron spectroscopy using two-dimensional electron detection and a camera in a single electron counting mode.

A brief description is given of an economical implementation of the read out of a two-dimensional detector in an electron spectrometer by a charge coupled device camera, using a pulse counting mode. Count rates up to 10 kHz can be handled in this way. A comparison with results obtained using a resistive anode detector is given for the case of electron scattering from Xe atoms.

Invited article: an improved double-toroidal spectrometer for gas phase (e,2e) studies.

A new spectrometer is described for measuring the momentum distributions of scattered electrons arising from electron-atom and electron-molecule ionization experiments. It incorporates and builds on elements from a number of previous designs, namely, a source of polarized electrons and two high-efficiency electrostatic electron energy analyzers. The analyzers each comprise a seven-element retarding-electrostatic lens system, four toroidal-sector electrodes, and a fast position-and-time-sensitive two-dimensional delay-line detector.

Spectral momentum densities in matter determined by electron scattering.

In electron momentum spectroscopy (EMS), an incoming energetic electron (50 keV in this work) ionizes the target and the scattered and ejected electrons are detected in coincidence (at energies near 25 keV). From the energy and momentum of the detected particles, the energy omega and momentum q transferred to the target can be inferred. The observed intensity distribution I(omega, q) is proportional to the spectral momentum density of the target and hence provides a direct challenge to many-body theoretical descriptions of condensed matter.