Photoinduced defects in the bromide-bridged platinum linear chain (Pt(en) sub 2 )(Pt(en) sub 2 Br sub 2 )(ClO sub 4 ) sub 4 (with en=ethylenediamine)

Journal Article · Mon Jun 15 00:00:00 EDT 1992 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.45.13185· OSTI ID:7292318

Donohoe, R J; Worl, L A; Arrington, C A; Bulou, A; Swanson, B I ^[1]

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1. Inorganic and Structural Chemistry Group, INC-4, MS-C345, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

Photoinduced defects in the bromide-bridged platinum linear chain (Pt(en){sub 2})(Pt(en){sub 2}Br{sub 2})(ClO{sub 4}){sub 4} (PtBr, where en=ethylenediamine) yield Raman, absorption, and electron paramagnetic resonance (EPR) signals that have been examined as a function of temperature in order to determine the kinetics of the decay of these metastable defects in an intermediate-strength low-dimensional charge-density-wave (CDW) solid. Both diamagnetic and paramagnetic defects are photogenerated with the initial excitonic transient primarily decaying to form electron bipolarons and hole polarons. The photogenerated Raman signal is indicative of the former and the EPR signal of the latter. The type and stability of these photoinduced defects are dependent on the sample history, with PtBr crystals grown in the orthorhombic phase (above 30 {degree}C) leading to greater variety and stability of defects as compared with those photoinduced in crystals grown in the monoclinic phase (below 10 {degree}C). The temperature dependence of the photogenerated spectroscopic signals reveals complicated decay routes, with the eventual recombination of valence defects mediated by lattice pinning potentials of various strengths, interconversion of defect states (including the possible melting'' of electron bipolarons into electron polarons) and a strengthening of the CDW as the crystals are warmed toward room temperature. The observation of bromide hyperfine splitting in the EPR data and the reversible intensity changes in the Raman defect signals indicates that these defects are spatially quite disperse, with ten or greater platinum sites revealed in the EPR signal, and demonstrates that the weakening of the CDW in PtBr relative to the strong CDW solid PtCl has a significant effect on the ground- and defect-state properties.

• OSTI ID: 7292318
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 45:23; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMINES
PHYSICAL RADIATION EFFECTS
CHLORATES
ETHYLENE
PLATINUM BROMIDES
CRYSTAL DEFECTS
DIAMAGNETISM
ELECTRON SPIN RESONANCE
EXCITONS
MAGNETIC PROPERTIES
NONLINEAR OPTICS
PARAMAGNETISM
PHOTON COLLISIONS
PLASMA WAVES
POLARONS
RAMAN SPECTRA
TEMPERATURE RANGE 0273-0400 K
ALKENES
BROMIDES
BROMINE COMPOUNDS
CHLORINE COMPOUNDS
COLLISIONS
CRYSTAL STRUCTURE
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
MAGNETIC RESONANCE
MAGNETISM
OPTICS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PLATINUM COMPOUNDS
QUASI PARTICLES
RADIATION EFFECTS
RESONANCE
SPECTRA
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
360606* - Other Materials- Physical Properties- (1992-)