Craig A. Kelly

Electron and energy transfer from CuI MLCT excited states

Abstract Electron and energy transfer processes from CuI MLCT excited states are reviewed. New results demonstrate clearly that these excited states undergo oxidative electron transfer quenching and energy transfer processes. The yields and dynamics of these processes have been spectroscopically quantified. Interfacial electron transfer from CuI MLCT excited states to wide band gap semiconductors has been observed. When utilized in photoelectrochemical cells, this interfacial electron transfer process provides a means for the conversion of light directly into electrical power.

Excited state processes at sensitized nanocrystalline thin film semiconductor interfaces

Abstract The existing and potential technological importance of nanocrystalline semiconductor thin films sensitized to visible light by molecular chromophores have initiated considerable efforts toward understanding the detailed mechanisms of photoprocesses occurring at the interface. However, such studies are made difficult by the complex nature of kinetic processes observed following light excitation. In this paper, we review literature reports of excited-state processes in these materials and attempt to clarify the underlying mechanisms responsible for the complex kinetic behavior typically observed.

Terahertz imaging and spectroscopy for landmine detection

Pulsed THz (100 GHz - 30 THz) Imaging Spectroscopy combines three ways of mine detection in one system, high resolution radar, depth ranging, and infrared spectroscopy. It allows minefield detection, single mine imaging, and near-zero false alarm due to the capabilities of explosives / plastic identification using spectroscopy with working distances to 1000 feet. We have previously demonstrated imaging capabilities with 1 mm spatial resolution on a rubber O-ring embedded in sand. The estimated transmission depth in moist sand is 1 to 3 cm, which should be sufficient for imaging anti-personnel mines. In this work, we present initial results investigating the feasibility of THz spectroscopy in the frequency range from 1 to 10 THz to detect and identify explosives and related compounds (ERCs). A major component of this effort is chemical modeling to obtain spectroscopic information on ERCs and environmental background. A time-domain THz system using femtosecond laser pulses is also being developed.

Estimates of hydride ion stability in condensed systems: energy of formation and solvation in aqueous and polar-organic solvents

Fundamental to its chemical and electrochemical—especially electrochromic—reactions, energies of formation of the hydride anion in several solvents (and concomitant solvation energies) were re-evaluated ia a radius estimate derived from differing theoretical approaches of satisfactory mutual consistency. The values (Gibbs free energies—ions at the standard 1 mol dm−3, gases at 100 kPa; 25°C) with subscripted error-estimates were, in kJ mol−1, for water 1414, acetonitrile 2079, N,N-dimethylformamide 22814, dimethyl sulfoxide 21911, methanol 1569 (a first estimate), and nitrobenzene 18311 (a first estimate). The aqueous, acetonitrile and N,N-dimethylformamide values are substantial revisions.