Accession Number : ADA256948


Title :   Radiationless Transitions and Excited-State Absorption in Tunable Laser Materials


Descriptive Note : Final rept. 1 Jun 1989-31 Jul 1992


Corporate Author : CONNECTICUT UNIV STORRS DEPT OF PHYSICS


Personal Author(s) : Bartram, Ralph H


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a256948.pdf


Report Date : Sep 1992


Pagination or Media Count : 50


Abstract : A coordinated experimental and theoretical investigation of fluorescence quenching and excited-state absorption was conducted on the chromium-doped halide elpasolites K2NaGaF6, K2NaScF6 and Cs2NaYC16, and on the laser-active T10(l) color center in KC1. Luminescence lifetime measurements on Cs2NaYC16:Cr3+ revealed a linear pressure dependence of the activation energy for thermal fluorescence quenching which was accurately predicted by a semi- empirical theoretical model incorporating quadratic coupling to an asymmetric mode. An ab-initio theoretical model, based on embedded-cluster and lattice- statics and dynamics calculations, accounted very well for optical and vibrational properties of these materials, but still needs refinement for reliable prediction of thermal quenching behavior. Two-photon excitation spectroscopy helped to explain broad-band excited-state absorption. Embedded- cluster calculations on laser-active color centers are in progress, with encouraging preliminary results. Non-radiative transitions, transition metals, chromium, tunable lasers, high pressure, luminescence, color centers.


Descriptors :   *OPTICAL PROPERTIES , *COMPLEX COMPOUNDS , *TUNABLE LASERS , *LASER MATERIALS , *CHROMIUM COMPOUNDS , COMPUTER PROGRAMS , METALS , PREDICTIONS , SPECTROSCOPY , MATERIALS , PHOTOLUMINESCENCE , TRANSITIONS , PHOTONS , HALIDES , PRESSURE , COLORS , QUENCHING , LASERS , HIGH PRESSURE , ENERGY , THERMAL LUMINESCENCE , ACTIVATION ENERGY , COLOR CENTERS , COUPLINGS , STATICS , LUMINESCENCE , ABSORPTION , BEHAVIOR , CHROMIUM , LATTICE DYNAMICS , EXCITATION , DYNAMICS , MODELS , FLUORESCENCE , TRANSITION METALS , ACTIVATION , MEASUREMENT


Subject Categories : Inorganic Chemistry
      Lasers and Masers
      Crystallography
      Optics


Distribution Statement : APPROVED FOR PUBLIC RELEASE