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.
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1995
- Accession Number
- ADA296391
Entities
People
- Jerry A. Boatz
- Mario E. Fajardo