Dicke photon trapping effects in molecular beam-foil experiments

William S. Bickel

Four experiments involving individual and combined effects of electric fields and multiple exciter foils on beam-foil-excited hydrogen atoms are described.The use of multiple exciter foils shows that excitation equilibrium does not occur in the thin carbon foils used here. The change of the rate of decay of Ly-α flux emitted by beam-foil excited hydrogen atoms in an electric field has been used to determine the relative populations of the 2s and 2p levels at the foil. The 2s level is overpopulated with respect to the 2p level when one foil is used and two exciter foils enhance the overpopulations. Photoelectric measurements of Ly-α flux and photographic measurements of the decay of Balmer-δ flux emitted by atoms in an electric field show that quasiperiodic intensity variations exist on the decay curve. The variations are attributed to the effect of the electric field but discrepancies arise between the experimental frequencies and those calculated from Stark-effect theory.

G. Franchetti, Frank Zimmermann, Muhammad Abdul Rehman

Akira Terasaki

Y. B. Band

I present a theory of the orientation and alignment of atoms observed upon emergence from tilted foils. The interaction with the foil surface is taken into account in the production process of particular states. Once they are produced, the evolution of these states, under the influence of the residual field near the surface, is calculated in the fashion introduced by Eck. The most general effect of this evolution is presented.

T. G. Eck

A simple model is presented in which the coherence between different ${m}_{L}$ states in a tilted-foil, beam-foil experiment is induced by the electrostatic interaction between each beam particle and the foil as a whole. Agreement between the predictions of this model and the experimental results of Berry et al. seems sufficient to warrant refinement of the model and further experiments.

P. R. Berman, J. Schmidt, Richard G. Brewer