Accession Number : ADA255278


Title :   Threshold Photodetachment Spectroscopy


Descriptive Note : Final rept. 1 Jul 1987-30 Sep 1991


Corporate Author : CALIFORNIA UNIV BERKELEY DEPT OF CHEMISTRY


Personal Author(s) : Neumark, Daniel M


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a255278.pdf


Report Date : 03 Sep 1992


Pagination or Media Count : 5


Abstract : The goal of this project is to learn about the electronic and vibrational spectroscopy of size-selected clusters. This is done using high resolution negative ion photodetachment techniques developed in our laboratory during the last four years. In our experiments, a beam of cluster anions (typically Cn- or Sin-) is generated using a laser vaporization source, mass- selected, and photodetached with a fixed frequency or tunable laser. In the fixed-frequency experiments, we measure the electron kinetic energy distribution, thereby obtaining the anion photoelectron spectrum. This enables us to map out the electronic and vibrational states of the neutral cluster with about 10 meV resolution. For higher (0.4 meV) resolution studies, we use a technique called threshold photodetachment spectroscopy. Here, the cluster anions are detached with a tunable laser, and only those photoelectrons produced with nearly zero kinetic energy are collected. In principle, this yields the same information as the photoelectron spectrum, but the considerably higher resolution allows us to make much more definite assignments of the spectral features. Carbon clusters, clusters, negative ion photodetachment, photodetachment, semiconductors, silicon dimer, transition states, transition state spectroscopy.


Descriptors :   *SPECTROSCOPY , *SEMICONDUCTORS , *TRANSITIONS , FREQUENCY , ELECTRONICS , DISTRIBUTION , MASS , CARBON , HIGH RESOLUTION , SILICON , PHOTOELECTRONS , VAPORIZATION , DIMERS , ANIONS , KINETICS , LABORATORIES , MAPS , ALLOCATIONS , KINETIC ENERGY , ELECTRONS , LASERS , RESOLUTION , ENERGY , NEUTRAL , IONS , TUNABLE LASERS


Subject Categories : Electrical and Electronic Equipment
      Atomic and Molecular Physics and Spectroscopy


Distribution Statement : APPROVED FOR PUBLIC RELEASE