Effects of anharmonicity on nonadiabatic electron transfer: a model

The effect of anharmonicity in the intramolecular modes of a model system for exothermic intramolecular nonadiabatic electron transfer is probed by examining the dependence of the transition probability on the exoergicity. The Franck-Condon factor for the Morse potential is written in terms of the Gauss hypergeometric function both for a ground initial state and for the general case, and comparisons are made between the first-order perturbation theory results for transition probability for harmonic and Morse oscillators. These results are verified with quantum dynamical simulations using wave-packet propagations on a numerical grid. The transition-probability expression incorporating a high-frequency quantum mode and low-frequency medium mode is compared for Morse and harmonic oscillators in different temperature ranges and with various coarse-graining treatments of the delta function from the Fermi golden rule expression. We find that significant deviations from the harmonic approximation are expected for even moderately anharmonic quantum modes at large values of exoergicity. The addition of a second quantum mode of opposite displacement negates the anharmonic effect at small energy change, but in the inverted regime a significantly flatter dependence on exoergicity is predicted for anharmonic modes.     

Unexpected reaction of 1,1,1,10,10,10-hexafluorodecane-2,4,7,9-tetrone with methyl trifluoroacetate

Hexane-2,5-dione or 1,1,1,10,10,10-hexafluorodecane-2,4,7,9-tetrone react with methyl trifluoroacetate in the presence of LiH to give, upon treatment with diluted acid, 6-hydroxy-9-oxo-2,4,10-tris(trifluoromethyl)-3,11,12-trioxatetracyclo[5,2,1,0^2,6,0^4,10]dodecane. The structure of this compound was determined by X-ray diffraction study.     

Anomalous polaron phenomena in the inward region of the exciton band

If the excitons have an intermediate radius and interact strongly with lattice deformations, the band being wide enough, then the exciton dispersion branch has a break in the central region of the band. The break is caused by the anomalous multiphonon scattering of excitons related to their trapping to local states.     

Finite-difference time-domain studies of light transmission through nanohole structures

We present theoretical studies on the transmission of light through subwavelength, circular apertures surrounded by circular groove structures. Finite-difference time-domain equations in cylindrical coordinates are provided for both dispersive materials and electrical conductors. The nanohole systems are composed of a circular hole in a slab, that is encircled by sinusoidal grooves defined by a period and depth. Light transmission is found to be extremely sensitive to the hole size, groove period, and groove depth. We determine a set of groove parameters that optimize transmission. Enhancements in transmission by approximately a factor of four can be achieved for silver in the visible when compared to the light incident upon the hole. These results may find utility in the design of nanoscale light manipulating devices. PACS 73.20.Mf; 78.20.Ci; 78.68.+m; 64.47.-n; 03.50.De