U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Physics

Condensed matter

Search Publications

Search Title, Abstract, Conference, Citation, Keyword or Author
  • Published Date
Displaying 1126 - 1150 of 1253

Electronic Correlations and Satellites in Superconducting Oxides

January 1, 1988
Author(s)
K Chang, Marvin Cohen, David R. Penn
The satellite observed at binding energy of 12-13 eV below the Fermi level in the high-T c oxide superconductors La 2-xSr xCuO 4 and YBa 2Cu 3O 7-δ is viewed as originating from a state with two holes bound at the same Cu site. As in the case of Ni metal

Free-electron-like Stoner Excitations in Fe

January 1, 1988
Author(s)
David R. Penn, S Apell
An analysis of spin-polarized electron-energy-loss experiments in Fe is described which (1) identifies the contribution of d-electron Stoner excitations, the usual type of Stoner excitation, (2) suggests that free-electron-like Stoner excitations are more

Electron Mean-Free-Path Calculations Using a Model Dielectric Function

January 1, 1987
Author(s)
David R. Penn
The inelastic electron mean free path as a function of energy is calculated for Cu, Ag, Au, and Al. The calculations are based on a model dielectric function ε(q,w), which is obtained from a modification of the statistical approximation. In this approach ε

Evidence for Free Electron-Like Stoner Excitation in Fe

January 1, 1987
Author(s)
David R. Penn
An analysis of spin-polarized electron-energy-loss experiments in Fe is described which suggests that (1) free-electron-like Stoner excitations are far more probable than the usual type and (2) exchange events involving relatively large energy losses are

Free Electron-Like Stoner Excitation in Fe

January 1, 1987
Author(s)
David R. Penn
Methods have recently developed to probe the Stoner excitation spectrum which has not been amenable to study by neutron diffraction. The experiments have utilized energy loss spectroscopy combined with spin polarization of the incident electron beam or

Scanning Tunneling Microscopy Applied to Optical Surfaces

January 1, 1986
Author(s)
Robert A. Dragoset, R Young, Howard P. Layer, S Mielczarek, E C. Teague, Robert Celotta
The technique of scanning tunneling microscopy has been applied to topographic mapping of two optical surfaces: a ruled grating replica and a diamond-turned gold mirror. We have demonstrated the ability of the scanning tunneling microscope to measure

Spin Polarized Secondary Electrons: Theory

January 1, 1986
Author(s)
David R. Penn, S Apell, S Girvin
We show that the spin polarization of the secondary electrons, P(E), yields useful information about the electron-electron interaction. The ration of majority to minority spin lifetimes is related to the measured values of P(E) by τ {uarr}(E)/τ {darr} (E =

Optical Properties of Small Metal Spheres: Surface Effects

April 25, 1983
Author(s)
David R. Penn, S Apell
It has been assumed that the optical properties of small spheres can be understood by means of a Drude dielectric function that incorporates a boundary scattering rate 1 / τ s~=v F / R, where vF is the Fermi velocity and R is the sphere radius. An

Anomalous Electron Energy Loss in Small Spheres

January 1, 1983
Author(s)
David R. Penn, S Apell
In analogy to the case of optical absorption, it is shown that inclusion of non-local surface effects results in a very large contribution to the energy loss of fast electrons scattered by a sphere. The scattering is found to be predominantly in the

The Diamond (111) Surface: A Dilemma Resolved

January 1, 1983
Author(s)
B B. Pate, B Waclawski, P M. Stefan, C Binns, T Ohta, M H. Hecht, P J. Jupiter, M L. Shek, Daniel T. Pierce, Nils Swanson, Robert Celotta, I. Lindau, W E. Spicer

Surface Photoeffect in Small Spheres

September 15, 1982
Author(s)
David R. Penn, R W. Rendell
A new method is developed to calculate the photoabsorption and photoyield of small spheres. Numerical results are presented for the case of free-electron spheres for photon energies below the plasmon energies. It is found that the excitation of electron

Dispersion Relation Approach to the X-Ray Edge Problem

December 15, 1981
Author(s)
David R. Penn, S Girvin, G D. Mahan
We present a dispersion relation formulation of the open-line amplitude for the x-ray edge problem within the contact potential model. Using both multiple-scattering and determinant techniques, we find that to a very good approximation the many-body

Surface Enhanced Photoadsorption and Photoyield in Small Spheres

October 12, 1981
Author(s)
David R. Penn, R W. Rendell
Calculations of the photoabsorption and photyield of small metal spheres are reported for photon energies below the plasmon energy. It is found that the excitation of electron-hole paris due to the presence of the surface results in (1) enhancements in the
Was this page helpful?