Accession Number : ADA296391

Title :   Monte Carlo Simulations of the Structures and Optical Absorption Spectra of Na Atoms in Ar Clusters, Surfaces, and Solids; a Detailed Presentation of the Theoretical Methods Used.

Descriptive Note : Special rept.,

Corporate Author : PHILLIPS LAB EDWARDS AFB CA

Personal Author(s) : Boatz, Jerry A. ; Fajardo, Mario E.

PDF Url : ADA296391

Report Date : JUN 1995

Pagination or Media Count : 60

Abstract : Optical absorption spectra of Na/Ar systems are calculated by combining the classical Monte Carlo simulation method with a quantum mechanical first-order perturbation scheme for estimating the energies of the Na (3p(2P)) excited states. The model incorporates many drastic approximations, but contains no adjustable parameters. Our Na/Ar matrix simulations generated relaxed structures for several candidate trapping sites based on various sized vacancies in fcc solid Ar. Trapping sites for which the equilibrium structures belong to the Oh or Td point groups yielded the experimentally well known triplet absorption lineshape; for these cases the splitting of the degeneracy of the excited Na (3p(2P)) state is due solely to fluctuation away from the equilibrium structures. Simulations of Na/Ar clusters, surfaces, and matrix sites possessing a strong permanent axial asymmetry yielded a widely split doublet plus singlet absorption lineshape. Despite our success at reproducing several qualitative aspots of the absorption spectroscopy of Na/Ar matrices, our simulations failed to quantitatively reproduce the experimental data. We discuss the major limitations of our model, as well as several possible improvements. (AN)

Descriptors :   *SODIUM, *ABSORPTION SPECTRA, *ARGON, *ATOMIC STRUCTURE, SIMULATION, OPTICAL PROPERTIES, EXPERIMENTAL DATA, MOLECULAR STATES, EXCITATION, MONTE CARLO METHOD, HIGH ENERGY, CLUSTERING, ASYMMETRY, RADIATION ABSORPTION, VISIBLE SPECTRA, DIATOMIC MOLECULES, GROUND STATE, MOLECULE MOLECULE INTERACTIONS, VACANCIES(CRYSTAL DEFECTS), ATOMIC SPECTROSCOPY, QUALITATIVE ANALYSIS, SPECTRAL LINES, MOLECULAR ENERGY LEVELS, SOLID PHASES, ALKALI METALS, RARE GASES.

Subject Categories : Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE