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In situ Raman spectroscopy was employed to investigate iron corrosion in air saturated water at a pressure of 25.1 MPa and temperatures from 21 to 537ЊC. Upon heating, various combinations of Fe 3 O 4 , ␣-Fe 2 O 3 , ␥-FeOOH, and ␥-Fe 2 O 3 were observed depending on the location on or temperature of the iron coupon. In some cases, different species were observed at the same temperature at different locations on the surface. This was attributed to oxygen concentration gradients in the solution caused by recirculation zones in the cell. The surface of the corrosion coupon changed little after it was heated to 537ЊC. This was attributed to the formation of a relatively thick, protective oxide scale after exposure to supercritical water. The ex situ Raman spectra were very similar to the in situ spectra obtained during cooling but different from those obtained during heating. This indicates that the corrosion layer present during cooling is similar to that observed ex situ but different from that observed during heating. Ex situ characterization of the coupon identified a two layered structure: an inner corrosion layer consisting of Fe 3 O 4 and ␣-Fe 2 O 3 and an outer layer consisting of ␥-Fe 2 O 3 and ␣-Fe 2 O 3 .

A new low-temperature chemical vapor deposition (CVD) method for the growth of metal and ceramic thin films has been demonstrated. This method involves the use of a lowpressure coflow diffusion reactor to react alkali metal vapor with metal halide vapor. The reaction chemistry is described by the following general equation: mnNaHere, Na is an alkali metal (e.g. Na, K, Cs, or Rb), M is a metal (e.g. Ti, Ta, Pt, W, ...) or nonmetal (e.g. B, C, Si, ...), X is a halogen (e.g. F, Cl, Br, or I), Ar is an inert gas (e.g. Ar or He), and m and n are integers. In this reaction, the alkali metal strips halogen from the metal halide. The metal is then free to grow into a thin film on a substrate placed in the reaction zone. Metal nitride or metal oxide ceramic films are easily formed by the introduction of nitrogen or oxygen gases into the reactor. Previously, this technique has been successfully employed for the production of nanoparticles and as an industrial synthesis route for the reduction of bulk metals from their metal halides. Now, for the first time, this reaction chemistry has been demonstrated to be a viable technique for thin film growth as well. Using the precursors of sodium metal vapor, titanium tetrachloride (the limiting reagent), and either Ar or N 2 gas, salt-free titanium (Ti), titanium nitride (TiN), and titanium silicide (Ti x Si y ) thin films have been grown on copper and silicon substrates. Guided by theoretical modeling calculations, reactant concentrations were adjusted to prevent gasphase particle nucleation and growth. Using this technique, we have produced salt-free titanium and titanium nitride thin films on copper substrates heated to 610 °C. This temperature is considerably lower than the 900-1200 °C required for the conventional thermal CVD of titanium. A composite salt/Ti film was grown on a silicon wafer at 260 °C, while at 610 °C, a salt-free titanium silicide thin film was produced. The quality and composition of the thin films were analyzed by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM).