Desorption dynamics of deuterium molecules from the Si(100)-(3×1) dideuteride surface

We measured polar angle ()-resolved time-of-flight spectra of D2 molecules desorbing from the Si(100)-(3×1) dideuteride surface. The desorbing D2 molecules exhibit a considerable translational heating with mean desorption kinetic energies of 0.25 eV, which is mostly independent of the desorption angles for 0°30°. The observed desorption dynamics of deuterium was discussed along the principle of detailed balance to predict their adsorption dynamics onto the monohydride Si surface

Coverage dependent desorption dynamics of deuterium on Si(100) surfaces: Interpretation with a diffusion-promoted desorption model

We studied coverage dependence of time-of-flight (TOF) spectra of D2 molecules thermally desorbed from the D/Si(100) surface. The mean translational energies Et of desorbed D2 molecules were found to increase from 0.20±0.05 eV to 0.40±0.04 eV as the desorption coverage window was decreased from 1.0 MLD0.9 ML to 0.2 MLD0 ML, being consistent with the kinetics switch predicted in the interdimer mechanism. The measured TOF spectra were deconvoluted into 2H, 3H, and 4H components by a curve fitting method along the principle of detailed balance. As a result, it turned out that the desorption kinetics changes from the 4H to the 3H situation at high coverage above D = 0.9 ML, while the 2H desorption is dominant for a quite wide coverage region up to D = 0.8 ML. A dynamic desorption mechanism by which the desorption is promoted by D-atom diffusion to dangling bonds was proposed

Modulated hydrogen beam study of adsorption-induced desorption of deuterium from Si(100)-3×1:D surfaces

We have studied the kinetic mechanism of the adsorption-induced-desorption (AID) reaction, H + D/Si(100)D2. Using a modulated atomic hydrogen beam, two different types of AID reaction are revealed: one is the fast AID reaction occurring only at the beam on-cycles and the other the slow AID reaction occurring even at the beam off-cycles. Both the fast and slow AID reactions show the different dependence on surface temperature Ts, suggesting that their kinetic mechanisms are different. The fast AID reaction overwhelms the slow one in the desorption yield for 300 KTs650 K. It proceeds along a first-order kinetics with respect to the incident H flux. Based on the experimental results, both two AID reactions are suggested to occur only on the 3×1 dihydride phase accumulated during surface exposure to H atoms. Possible mechanisms for the AID reactions are discussed

New high-resolution phonon spectroscopy using impulsive stimulated Brillouin scattering

Impulsive stimulated Brillouin scattering is applied to a new high-resolution phonon spectroscopy, where phonons created by two crossing pump pulses are observed using diffraction of a cw probe light in both time and frequency domains. In time domain, real-time behavior can be detected sensitively using a digital oscilloscope, while in frequency domain, measurements with high resolution are attainable by means of a spherical Fabry–Perot interferometer. Several examples of the measurements on liquid samples are demonstrated for clarifying various aspects of the phonon generation by the present method: the mechanism of the generation under pulsed light irradiation, the propagation of the generated phonon, the resonance excitation, and the interference with the other nonlinear optical processes. The relation with the ordinary light scattering is also discussed

Polymerized ionic liquids as durable antistatic agents for polyether-based polyurethanes

Ionic liquid (IL) fillers, which are composed of polymerized [2-(methacryloyloxy)ethyl]trimethylammonium bis(trifluoromethanesulfonyl)imide, were applied as antistatic agents for polyether-based polyurethane (PU). Surface and volume resistivities of 10 10 Ω sq −1 and 10 8 Ω cm, which are hundred times smaller than those of pristine PU and also are desired values for realizing antistatic effects, were achieved at the concentration of fillers of only 1000 ppm. The fillers exhibited excellent antistatic effect, equivalent to the effect caused by conventional ILs, even though the fillers are solid particles. Temperature dependence of ionic conductivity of the intrinsic fillers was found to follow the Arrhenius model, while that of the filler-PU composites followed the Vogel–Fulcher–Tammann model. This suggests that IL units of the fillers are effectively dissociated in the polyether matrix, and migration of the dissociated ions occurs associated with the relaxation of polyether chains. Employing the polymerized ILs, the reduced resistivity was retained also after ultrasonication treatment of films in methanol. The polymerized IL fillers are concluded to be promising additives for the sustainable and durable antistatic treatment of polyurethanes