Accession Number : ADA251602


Title :   The Na4(+3) Clusters in Sodium Sodalite


Descriptive Note : Journal article


Corporate Author : CALIFORNIA UNIV SANTA BARBARA DEPT OF CHEMISTRY


Personal Author(s) : Srdanov, V I ; Haug, K ; Metiu, H ; Stucky, G D


Full Text : http://www.dtic.mil/dtic/tr/fulltext/u2/a251602.pdf


Report Date : 15 May 1992


Pagination or Media Count : 33


Abstract : We have measured and calculated the absorption spectrum of the Na4(3+) clusters in Na3(AlSiO4)3 sodalite prepared by high vacuum deposition of sodium atoms. The samples with a Na4(3+):Na3(3+) cluster ratio up to 1:10 show a single absorption feature with lambda max = 628 run (1.99 eV). The absorption originates from the individual sodalite cages containing Na4(3+) cluster. For the Na4(3+):Na3(3+) cluster ratio larger than 1:10, when some of the Na4(3+) clusters are likely to interact, the changes in absorption spectra indicate the onset of metal-insulator transition. Time dependent quantum mechanical calculations of the photon absorption cross section of Na4(3+) clusters in sodalite at infinite dilution were carried out. The dependence of the calculated spectra on sodalite framework charges and cluster geometry was used to determine which of the proposed charge distribution models are consistent with the absorption spectra. The best agreement between measurements and calculations is obtained for Na = +1, Si = +1.9, Al = +0.9, O = -0.95.


Descriptors :   *ABSORPTION SPECTRA , HIGH VACUUM , RATIOS , MODELS , DISTRIBUTION , DIELECTRICS , VACUUM , SODIUM , ATOMS , TIME , DEPOSITION , SPECTRA , CROSS SECTIONS , GEOMETRY , PHOTONS , TRANSITIONS , ABSORPTION , AGREEMENTS , DILUTION , ABSORPTION CROSS SECTIONS , VACUUM DEPOSITION , STOICHIOMETRY , MINERALS , METALS , MEASUREMENT


Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Geology, Geochemistry and Mineralogy
      Crystallography


Distribution Statement : APPROVED FOR PUBLIC RELEASE