Energy transfer in anisotropic systems: A. Excitation migration in substitutionally disordered one-dimensional solids. B. The spectroscopy of molecules adsorbed on metal surfaces
The energy and dynamics of excited states in a variety of anisotropic environments, including isotopically and chemically mixed crystals and molecular overlayers adsorbed on a nickel (111) surface, are investigated. The relationship between local and long-range structure and spectroscopic properties is explored. A theory for energy transfer in substitutionally disordered solids is presented. Explicit expressions for the ''diffusion'' coefficients and the energy partitioning ratios in binary systems are derived. Energy transfer between localized states is found to be facilitated by concurrent tunnelling and thermal promotion. Experimental results for triplet energy partitioning between mobile and stationary trap states as a function of mobile trap concentration in the ternary d/sub 2/-1,2,4,5-tetrachlorobenzene--h/sub 2/-1,2,4,5-tetrachlorobenzene--pyrazine system are analyzed. It is shown that both tunnelling and thermal detrapping contribute to triplet exciton mobility below 4.2 K. Singlet exciton migration makes an important contribution to trap equilibration before intersystem crossing to the triplet manifold. Spin coherence experiments are used to determine the energy level structure, physical geometry, and exciton dynamics of a series of impurity-induced traps in 1,2,4,5-tetrachlorobenzene. The uv spectra of pyrazine, pyridine, and naphthalene adsorbed on a nickel single crystal (111) surface are measured by spectroscopic ellipsometry at low temperatures. The excited electronic and vibronic energy levels measured are similar to bulk molecular crystal values, but pyrazine and pyridine show small, but significant deviations. The ordering of molecular overlays is observed spectroscopically and information about overlayer crystal structure is deduced. 148 references, 48 figures, 5 tables.
- Research Organization:
- California Univ., Berkeley (USA). Lawrence Berkeley Lab.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6500839
- Report Number(s):
- LBL-8332
- Country of Publication:
- United States
- Language:
- English
Similar Records
Studies of energy transfer processes in triplet states using optically detected magnetic resonance
Coherence in electronically excited dimers. III. The observation of coherence in dimers using optically detected electron spin resonance in zero field and its relationship to coherence in one-dimensional excitons
Related Subjects
360104 -- Metals & Alloys-- Physical Properties
640305* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Theory-- (-1987)
74 ATOMIC AND MOLECULAR PHYSICS
ACTIVATION ENERGY
ADSORPTION
ANISOTROPY
AROMATICS
AZINES
CHLORINATED AROMATIC HYDROCARBONS
CONDENSED AROMATICS
CRYSTAL STRUCTURE
CRYSTALS
DEUTERIUM COMPOUNDS
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY
ENERGY TRANSFER
EXCITONS
HALOGENATED AROMATIC HYDROCARBONS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROGEN COMPOUNDS
LOW TEMPERATURE
METALS
MONOCRYSTALS
NAPHTHALENE
NICKEL
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
POTENTIAL ENERGY
PYRAZINES
PYRIDINES
QUASI PARTICLES
SOLIDS
SORPTION
SORPTIVE PROPERTIES
SPECTRA
SURFACE PROPERTIES
TRANSITION ELEMENTS
TRAPS
TUNNEL EFFECT
ULTRALOW TEMPERATURE
ULTRAVIOLET SPECTRA