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Research has been conducted on the photosubstitution wavelength dependence. Photoinduced electron transfer and the time-resolved Cr(CNPh) (sub)6 spectra have been investigated.

Research has been conducted on the electrochemical behavior of W(CO) (sub)4 (phen) to investigate the role of electron transfer in the photochemical reactivity of the compound. Results show that the photoreactivity of this complex can involve an electron-transfer pathway.

A new approach to the use of high-field instruments for cross-polarization (CP) magic angle spinning (MAS) 13C NMR for analysis of humic materials is described. This technique consists of using a high sample spinning rate and a ramp CP pulse sequence, which, among other advantages, addresses chemical shift anisotropy effects. The theoretical aspects of high spinning rates on line broadening for nonrigid solids are reviewed. Also, the ramp CP pulse sequence and its implications for humic materials are discussed. It is shown that the highest resolution and most informative spectra can be obtained via a high-field instrument if the sample is spun at a rate higher than 0.25 of the anisotropy of the chemical shift of the aromatic moieties and a ramp CP pulse sequence is used. This study raises concerns that previous methods may have underestimated the amount of aromatic carbons in humic materials. Because of the similarities between humic materials and coals, this work may also have implications in the CP-MAS 13C NMR approach to coals.

The quenching of fluorescence of a fulvic acid by metal ions has been revisited in this study. Fluorescence quenching has been used in the past to establish the extent of metal ion binding to fulvic acids. Both emission and synchronous fluorescence show that the relationship between the extent of quenching and fraction of cation sites occupied is not linear. It was also found that synchronous fluorescence is a more revealing measurement than emission. Similar patterns of components can be assigned from both time-resolved fluorescent measurements and synchronous fluorescence. Correlation of these two distinct types of measurements suggests that a three-component treatment of fulvic acid luminescence may be physically meaningful. For this fulvic acid the three components may be assigned lifetimes and wavelength maxima as follows; [approximately] 50 ps (392 nm), [approximately] 430 ps (465 nm), and 4.2 ns (512 nm). The three-component model accommodates pH dependence and metal ion quenching. Stern-Volmer plots also support a (minimum) three-component model.

Time-resolved UV-vis absorption spectroscopy and nano-second flash photolysis analyze the photoreactions of three (CO)(5)ReMn(CO)(3) (alpha-diimine) complexes at different temperatures and pressures. Primary photoprocess in the metal-to-ligand charge-transfer excitation of these complexes is a fast CO dissociation from Mn center. High reactivities of these complexes are due to an available Mn coordination site and a weak Re-M bond.

Post excitation photochemical analysis of fast photooxidation of transition metal maleonitriledithiolate complexes reveal that the solvent dependence is independent of wavelength dependence. The purely electronic charge transfer to solvent state mixing controls wavelength dependence. Picosecond spectroscopy reveals the absence of reversible electron transfer.

The excitation into the ligand-field at 355 nanometers is used to calculate the picosecond (PS) time-resolved absorption spectra of W(CO)5(4-cyanopyridine). The excitation into the metal to ligand charge-transfer, MLCT at 532 nanometer absorption bands is used to calculate the spectra of W(CO)5(4-formylpyridine). The long-lived 3MLCT excited state is seen when the temporary absorption spectrum is being formed, which increases after biphasic unities. A sub-PS method is exhibited by the more rapid constituents, while the gradual constituents exhibit varying values for the two compounds, when subjected to 355nm of excitation in toluene solution.

The photochemical reaction of W(CO)4phen was studied using both ligand field (LF) and metal-to-ligand charge transfer (MLCT) excitation. A concentration dependence was observed under LF irradiation in CH2Cl2 where quantum yield increased from 0.011 to 0.017 when concentrations of (n-Bu)3P were increased from 0.015 to 0.36 M. This was similar to the observations for the MLCT band in the same system. Results with other reagents showed that quantum yield values increase significantly under conditions of increasing excitation wavelength for chlorinated solvents.

A photosolvation competition study was conducted to probe the dependence of product selection in the photoinduced substitution reaction of W(CO)5py to excitation wavelength. The significance of the bound states in W(CO)5py was increased with the decrease of excitation energy due to the bound state's ability to trap the excitation wavelength. The role of excess excitation energy in establishing the future of a geminate pair was demonstrated in the results of the experiment.