James E. Bayfield

Design and Operation of an Atomic Hydrogen Target for Precision Scattering Cross Section Measurements

A new design for a hydrogen atom target is described. An H2 dissociation of 96±4% is obtained for pressures near 3×10‐5 Torr and temperatures of about 2400 K. The scattering cell proper is uniformly heated by radiation from a separate resistance heater element. Magnetic field effects are eliminated by gating the 700 A heater current out of phase with the incident particle beam. A method for absolute measurement of the dissociation fraction is described. Target impurities other than H2 are estimated to be less than 0.2%.

Continuous‐wave source of highly excited atoms using Doppler‐tuned ir laser radiation

A 10‐keV atomic beam source of hydrogen atoms in the n=44 or other selected state was based upon charge exchange production of the n=10 state followed by Doppler‐tuned cw CO2 laser excitation to the desired highly excited state. In present operation the output atom flux of the source is 2.5×105 sec−1, a value that can be increased by as much as 105. The technique can be extended to considerably higher and lower atom energies, to a wide range of atom quantum numbers, and to atoms other than hydrogen.

Electron Transfer in Simple Atomic Collisions: Recent Theory, Experiment, and Applications

The search for the mechanisms underlying the transfer of particles and/or energy between interacting atoms or molecules continues to fascinate many investigators in physics, chemistry and biology. Most interesting are those processes which are unusally probable and highly specific, requiring special conditions such as internal energy resonance during some portion of the collisional interaction time. The general questions are:Under what conditions can particles and/or energy be transferred? How can we control these conditions and study the processes in the laboratory?;and Can we make predictive calculations to verify our physical understanding and eliminate the need to do uninteresting experiments? The answers to these questions are not generally available except for some simple atom-atom collisions and a few triatomic cases such as H+ + H2. And we shall see that much remains to be understood even for those simple systems extensively studied in the four years following the closing dates for past monographs on electron transfer.1–5