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Partial internal energy distributions of the hydroxyl reaction products of O(1D)+H2, HD, and D2 reactions are presented. Inverted rotational distributions, preferential population of the π+ lambda doubling sublevels, and statistical population of the spin sublevels are observed. A slight preferential formation of the OD vs OH reaction products observed is measured for the reaction of O(1D)+HD. Surprisal analysis of these results indicates both dynamical and kinematic constraints on the reaction dynamics. Comparison of these results with published model calculations suggest that an insertion mechanism to form a highly energetic collision complex dominates the reaction dynamics.

Diamond exhibits very high, but widely varying, secondary-electron yields. In this study, we identified some of the factors that govern the secondary-electron yield from diamond by performing comparative studies on polycrystalline films with different dopants (boron or nitrogen), doping concentrations, and surface terminations. The total electron yield as a function of incident-electron energy and the energy distribution of the emitted secondary electrons showed that both bulk properties and surface chemistry are important in the secondary-electron-emission process. The dopant type and doping concentration affect the transport of secondary electrons through the sample bulk, as well as the electrical conductivity needed to replenish the emitted electrons. Surface adsorbates affect the electron transmission at the surface-vacuum interface because they change the vacuum barrier height. The presence of hydrogen termination at the diamond surface, the extent of the hydrogen coverage, and the coadsorption of hydrocarbon-containing species all correlated with significant yield changes. Extraordinarily high secondary-electron yields (as high as 84) were observed on B-doped diamond samples saturated with surface hydrogen. The secondary electrons were predominantly low-energy quasithermalized electrons residing in the bottom of the diamond conduction band. Two key reasons for the unusually high yields are (1) the wide band gap which allows the low-energy secondary electrons to have long mean-free paths, and (2) the very low or even negative electron affinity at the surface which permits the low-energy quasithermalized electrons that reach the surface to escape into vacuum.

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A concept combining optics and microwave pulses with the negative charge-state of the nitrogenvacancy (NV --) center in diamond is demonstrated through experiments that are equivalent to single-qubit gates, and decoherence for this qubit is examined. The spin levels of the ground state provide the two-level system. Optical excitation provides polarization of these states. The polarized state is operated coherently by 35 GHz microwave pulses. The final state is read out through the photoluminescence intensity. Decoherence arises from different sources for different samples. For high-pressure, high-temperature synthetic diamonds, the high concentration of substitutional N limits the phase-memory to a few ms. In a single-crystal CVD diamond, the phase memory time is at least 32 ms at 100 K. 14 N is tightly coupled to the electronic spin and produces modulation of the electron-spin echo decay under certain conditions. A two-qubit gate is proposed using this nuclear spin. This demonstration provides a great deal of insight into quantum devices in the solid state with some possibility for real application. IntroductionThe nitrogen-vacancy center in its negative charge-state (NV --) in diamond is a defect/host system with remarkable properties. Its optical transition and spin were established through optical studies and EPR [1,2]. A long spin lifetime and more details of the energy levels were obtained through Optically Detected Magnetic Resonance (ODMR) and Raman heterodyne spectroscopy at zero and small magnetic fields [3,4]. These studies and others confirmed that the center has a strong optical transition and a long-lived spin with S ¼ 1 in the ground state. Many further experiments have been performed including room temperature ODMR of single NV --centers [5].The strong optical transition, long spin lifetimes, and stability of NV --in diamond have led naturally to concepts and demonstrations aimed at quantum information technology. One approach employs the 13 C nuclear spins as qubits with radio-frequency pulses as gates to implement a quantum computer [6]. A second approach makes use of cavity dark states for quantum computing [7]. Other works use the NV --center as a single-photon source for application in quantum communication [8,9].In this work, a concept is demonstrated that uses the electronic spin of the NV --in diamond as the qubit with optical polarization, microwave pulses as operators, and optical emission for readout. Gates involving a single qubit are demonstrated with ensembles of NV --centers. Previous work with one sample [10] has been extended to a set of samples, and some of the causes of decoherence can now be given. The involvement of