The K-shell near-edge X-ray absorption fine structure spectra of solid CbO and Ciu have been recorded with high spectral resolution. The spectra exhibit sharp resonances associated with transitions to unfilled P* molecular orbitals and, at higher energy, broader resonances associated with cJ*-like orbitals. The observed energy splitting of the x* resonances can be accounted for by published extended Hiickel calculations. Our data clearly reveal that the fullerene films resemble molecular solids with considerably stronger intra-molecular than inter-molecular interactions.

The C 1s and O 1s core-level photoabsorption spectra of poly͓2-methoxy,5-͑2Ј-ethyl-hexoxy͒-1,4-phenylene vinylene͔ ͑MEH-PPV͒ before and after exposure O 2 and broadband visible light were recorded to determine the degradation pathway for this polymer. The change in the O 1s spectra as a function of exposure demonstrates that the O adds to the polymer chain to form a carbonyl group. Exposure to only O 2 or only light causes no change in the C 1s or O 1s spectra. In the C 1s spectra, the change in the dependence on the photon angle of incidence after exposure demonstrates that O attacks the polymer at the double bond in the vinyl group thereby altering the extended conjugation of the polymer.

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The chemisorption and reaction of dichlorosilane (SiH2Cl2) with Si(111) and Si(100) surfaces is investigated with core-level soft x-ray photoelectron spectroscopy employing synchrotron radiation, in order to ascertain the surface chemistry involved in atomic layer epitaxy (ALE). Exposures to 8 kL of SiH2Cl2 were performed as a function of sample temperature in the range from room temperature to 800 °C. At all temperatures, SiH2Cl2 chemisorbs dissociatively forming silicon monochloride surface species. The coverage of monochloride displays a maximum for exposures at ∼600 °C. Under all conditions studied, larger chlorine coverages are observed on Si(100) than on Si(111). A Si surface that was first saturated with SiH2Cl2 at 600 °C was subsequently exposed to H2 at 600 °C, and no reaction occurred. These results indicate that recent models for silicon ALE are incorrect. An alternative method for low-temperature ALE of Si is proposed, in which SiH2Cl2 is adsorbed onto Si at 600 °C and Cl is removed via reaction with atomic H.