Research in Infrared and Optical Quantum Electronics. A. Infrared Sensitivity of Plasmas. B. Picosecond Dynamics of Surface Photoelectrons.
Abstract
Upon discovery of the infrared sensitivity of weakly ionized plasmas, research was initiated at establishing the quantum origins of the observed interactions. Taking into account the obvious inverse bremsstrahlung process, studies were made to evaluate the role of bound-bound and bound-free transitions under the influence of low energy photon flux corresponding to the intermediate and far-infrared portions of the spectrum. It was established and documented that in a broad range of electron temperatures and densities of weakly ionized plasmas, the bound-free transitions induced by infrared photons affect the recombination process to a significant and, frequently, to a dominant degree. Theoretical results are obtained on the basis of a hydrogenic model. Experiments demonstrate the generality of the infrared sensitivity of plasmas. A separate phase of research in optical quantum electronics dealt with optical interaction with surface and near surface electrons in photoemissive materials. In particular, the dynamics on picosecond time scales of electrons released from the surface and near-surface of select materials is of both fundamental and practical interest. Negative electron affinity materials, known for their high quantum efficiency, are predicted to exhibit maximum time dispersion of a step excitation. Preliminary studies and the development of tools needed for an experimental determination of parameters on picosecond time scales, were the principal goals of this effort. As a byproduct, a patent was filed and granted on the more successful configurations of devices designed to carry out the basic surface emission studies.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1976
- Accession Number
- ADA033947
Entities
People
- Henry Merkelo
Organizations
- University of Illinois Urbana–Champaign