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Rates of halide oxidation and injected electron-oxidized dye recombination are assessed for two sensitizers. Results suggest a wavelength-dependent electron injection yield.

Research was conducted to examine the ring closure of CpMn-type complexes using time-resolved experiments. The quantum yields for ring closure were observed to be only 0.6 and were independent of chain length. Photoacoustic calorimetry, transient infrared and molecular mechanics studies reveal that ring closure following photolysis of (eta-5-C5H4R)Mn(CO)3 complexes can be extremely fast. Findings also indicate that the ring closures can take place through two pathways of distinct time scales.

(Et)3SiOH:base:CCl4 hydrogen-bonded reactions reduce the intrinsic OH-stretch vibrational population lifetime. The OH-stretch population lifetime for (Et)3SiOH:base:CCl4 hydrogen-bonded solutions was measured using a picosecond infrared pump-probe. Analysis of the base concentration dependence of the free OH-stretch vibrational deactivation reveal that deactivation is basically insensitive to the base's proton-accepting strength and that hydrogen-bonding interactions are important. The k(sub BM) value is consistent with the experimental results.

We directly compare relative carrier mobilities in semiconducting organic polymer films measured using noncontact optical pump terahertz (THz) probe spectroscopy to those reported in electrical device studies. Relative transient signal amplitude measurements of photoinjected carrier mobility as a function of poly-3-hexylthiophene (P3HT) molecular weight correlate directly with electrical device test values, indicating that the THz method shows promise as a rapid material screening approach. We also present measurements on P3HT conducting films as a function of structural regularity, dispersing solvent, addition of C60 electron traps, sample temperature, and other growth parameters relevant to device manufacture. [ABSTRACT FROM AUTHOR]

Ultraviolet pump, infrared probe transient absorption studies of the chelatable compound, Mn{[[eta].sup.5]-[C.sub.5][H.sub.4]C(O)C[(SC[H.sub.3]).sub.3]}[(CO).sub.3], dispersed in room temperature, spin-coated polyacryclonitrile (PAN) films are presented. The analysis has shown that efficient chelation can be used as a mechanistic platform for the development of ultrafast solid-state optical molecular devices.

The photoinduced dynamics of three new [Cr{[eta.sup.6]-[C.sub.6][H.sub.5]C(O)R}[(CO).sub.3] complexes are examined by using ultraviolet (UV) pump/infrared (IR) probe transient absorption spectroscopy in three solvents, n-heptane, tetrahydrofuran (THF) and acetonitrile. The results have shown that the reaction rates and chelation pathways of the chromium series complexes have depended on the conformational accessibility of the chelatable side group.

Ultrafast chelation dynamics following UV irradiation of manganese complexes 1, 2, and 3 demonstrate that Irradiation of 1 or 2 alkane solvent results in competition between direct chelate formation and solvent coordination on the picosecond time scale, whereas irradiation of 3 in alkane solvent leads only to chelation and exclusion of ultrafast solvent coordination. Chelation occurs in acetonitrile, for all three complexes in less than 13 ps without ultrafast solvent coordination.

Terahertz time domain (THz - TDS) and optical heterodyne-detected Raman-induced Kerr effect (OHD-RIKES) spectroscopic techniques as probes of molecular and vibrational dynamics in the frequency range of 0.1 to 6 THz (3 to 200 cm(super -1)) is compared. Significant differences are found between the THz and OHD-RIKES spectra of benzene and bromobenzene that cannot be traced to rescaled oscillator strengths within a set of fixed-frequency modes.

The ring formation with the organometallics as a mechanism for an ultrafast photoswitch is investigated. The photoinduced dynamics of cyclopentadienyl manganese tricarbonyl derivatives are investigated in n-heptane solution on the ps to micro seconds scale by UV-pump IR-probe transient absorption spectroscopy.