The OH(X 2 Π) radical in a 20:80 tetraethoxysilane (TEOS)/O 2 plasmas has been characterized during deposition of SiO 2 using the imaging of radicals interacting with surfaces (IRIS) method. The reactivity of OH at the surface of a growing SiO 2 film has been determined as a function of the applied radio-frequency (rf) plasma power (P) and the substrate temperature (T S ). The reactivity (R) of OH during deposition of SiO 2 on a 300 K Si substrate is 0.41 ( 0.04. R decreases as substrate temperature increases but is unaffected by increasing rf power. Translational and rotational temperatures (Θ T and Θ R , respectively) of the OH radical are also determined. For a 20:80 TEOS/O 2 plasma (P ) 85 W), Θ T ) 912 ( 20 K and Θ R ) 450 ( 20 K. Θ T is significantly higher than Θ R and increases with increasing rf power. Using isotopically labeled 18 O 2 as a precursor, the source of the oxygen in OH is identified as the O 2 gas, not oxygen from the ethoxy groups on TEOS. With these data, the role of OH in deposition of SiO 2 from TEOS-based plasmas and the effects of plasma deposition parameters on film formation are discussed.

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Interligand electron transfer kinetics have been measured in OsII(bipyridine)3 following photoexcitation to the metal-to-ligand charge-transfer state. The measurements are made in room temperature solutions of acetonitrile, ethylene glycol, and glycerol, using time-resolved absorption polarization spectroscopy. The experimental results are strongly dependent on excitation wavelength and are in agreement with the results of reaction/diffusion model calculations. In the calculations, motion along the solvent polarization coordinate is treated as diffusion, and reaction is treated in the nonadiabatic (acetonitrile) or adiabatic (ethylene glycol) limits. The adjustable parameters of the model are the interligand electronic coupling and the solvent polarization barrier height, which are taken to be 15 and 500 cm-1, respectively. The relaxation processes giving rise to the observed kinetic components are discussed.