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Yasuo Cho - One of the best experts on this subject based on the ideXlab platform.
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atomic dipole Moment Distribution on a hydrogen adsorbed si 111 7 7 surface observed by noncontact scanning nonlinear dielectric microscopy
Applied Physics Letters, 2013Co-Authors: Daisuke Mizuno, Kohei Yamasue, Yasuo ChoAbstract:Noncontact scanning nonlinear dielectric microscopy (NC-SNDM) can atomically resolve the polarization Distribution on material surfaces. We observed a hydrogen-adsorbed Si(111)–(7 × 7) surface using NC-SNDM and found that hydrogen-adsorbed Si adatoms had lower dipole Moments than bare Si adatoms. We discuss the charge Distribution around a hydrogen-adsorbed Si adatom in terms of its geometry and the electronegativities of hydrogen and silicon. Our model suggests that the charge Distribution around a hydrogen-adsorbed adatom is nearly symmetric and it qualitatively explains the experimental results. We thus conclude that the hydrogen-adsorbed Si adatoms are both electrically and chemically passivated.
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atomic dipole Moment Distribution of si atoms on a si 111 7 7 surface studied using noncontact scanning nonlinear dielectric microscopy
Physical Review Letters, 2007Co-Authors: Yasuo Cho, Ryusuke HiroseAbstract:A local atomic electric dipole Moment Distribution of Si atoms on Si(111)-(7 x 7) surface is clearly resolved by using a new technique called noncontact scanning nonlinear dielectric microscopy. The dc-bias voltage dependence of the atomic dipole Moment on the Si(111)-(7 x 7) surface is measured. At the weak applied voltage of -0.5 V, a positive dipole Moment is detected on the Si adatom sites, whereas a negative dipole Moment is observed at the interstitial sites of inter Si adatoms. Moreover, the quantitative dependence of the surface dipole Moment as a function of the applied dc voltage is also revealed at a fixed point above the sample surface. This is the first successful demonstration of direct atomic dipole Moment observation achieved in the field of capacitance measurement.
Ryusuke Hirose - One of the best experts on this subject based on the ideXlab platform.
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atomic dipole Moment Distribution of si atoms on a si 111 7 7 surface studied using noncontact scanning nonlinear dielectric microscopy
Physical Review Letters, 2007Co-Authors: Yasuo Cho, Ryusuke HiroseAbstract:A local atomic electric dipole Moment Distribution of Si atoms on Si(111)-(7 x 7) surface is clearly resolved by using a new technique called noncontact scanning nonlinear dielectric microscopy. The dc-bias voltage dependence of the atomic dipole Moment on the Si(111)-(7 x 7) surface is measured. At the weak applied voltage of -0.5 V, a positive dipole Moment is detected on the Si adatom sites, whereas a negative dipole Moment is observed at the interstitial sites of inter Si adatoms. Moreover, the quantitative dependence of the surface dipole Moment as a function of the applied dc voltage is also revealed at a fixed point above the sample surface. This is the first successful demonstration of direct atomic dipole Moment observation achieved in the field of capacitance measurement.
Kohei Yamasue - One of the best experts on this subject based on the ideXlab platform.
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improved study of electric dipoles on the si 100 2 1 surface by non contact scanning nonlinear dielectric microscopy
Applied Physics Letters, 2014Co-Authors: Masataka Suzuki, Kohei Yamasue, Yoshiaki SugimotoAbstract:We studied a Si(100)-2 × 1 surface by non-contact scanning nonlinear dielectric microscopy (NC-SNDM). Simultaneously taken images of the topography and electric dipole Moment Distribution show that negative electric dipole Moments are locally formed on individual dimers on the surface. In addition, we obtained the dc bias voltage dependence of the elocal(3) signal on a specific dimer by using an atom-tracking technique with NC-SNDM. We observed that the electric dipole induced a surface potential of around −250 mV on the dimer.
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atomic dipole Moment Distribution on a hydrogen adsorbed si 111 7 7 surface observed by noncontact scanning nonlinear dielectric microscopy
Applied Physics Letters, 2013Co-Authors: Daisuke Mizuno, Kohei Yamasue, Yasuo ChoAbstract:Noncontact scanning nonlinear dielectric microscopy (NC-SNDM) can atomically resolve the polarization Distribution on material surfaces. We observed a hydrogen-adsorbed Si(111)–(7 × 7) surface using NC-SNDM and found that hydrogen-adsorbed Si adatoms had lower dipole Moments than bare Si adatoms. We discuss the charge Distribution around a hydrogen-adsorbed Si adatom in terms of its geometry and the electronegativities of hydrogen and silicon. Our model suggests that the charge Distribution around a hydrogen-adsorbed adatom is nearly symmetric and it qualitatively explains the experimental results. We thus conclude that the hydrogen-adsorbed Si adatoms are both electrically and chemically passivated.
Yan Y. Kagan - One of the best experts on this subject based on the ideXlab platform.
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seismic Moment Distribution revisited ii Moment conservation principle
Geophysical Journal International, 2002Co-Authors: Yan Y. KaganAbstract:SUMMARY We compare the tectonic rate with earthquake data using several theoretical Distributions to approximate the seismic Moment‐frequency relation. We derive formulae to estimate parameters of the seismic Moment Distributions by comparing the earthquake occurrence rate with tectonic strain. We analyse the tectonic Moment rate and the earthquake Moment Distribution for several types of tectonic environments, including subduction zones, plate bounding transform faults and deforming continental regions. In this analysis we use finer subdivisions of tectonic regions to infer whether earthquake size Distribution properties established previously for large provinces (Flinn‐Engdahl seismic regions) could be applied to smaller zones extending over a few hundred kilometres. Although the shortness of the available earthquake catalogues makes our results less reliable, several conclusions can be drawn from the analysis. The universality of the β-parameter (the slope of the Moment‐frequency relation) is reasonably well confirmed for all of these tectonic regions and their subdivisions. In each region, we estimate the strain rate or relative plate motion from a plate tectonic model, active fault data or geodetic data. According to the Moment‐frequency relation, the ratio of the tectonic Moment rate to the earthquake rate depends on the β value, the corner magnitude (mc) and the effective seismogenic thickness. We find that this ratio does not vary systematically with the relative plate velocity, the ratio of parallel to perpendicular plate motion, time since the last major earthquake and the length of fault zone segments established by previous earthquake history. We obtain similar results for the western United States and southeast Asia; the corner magnitude is approximately equal to that for the circum-Pacific Rim and there is no systematic dependence of the mc parameter on a geographic region or strain rate. Assuming the commonly accepted values for seismogenic thickness, elastic modulus and 100 per cent seismic coupling, the corner magnitude values for plate boundary zones and continental areas are 8.3‐8.8, i.e. similar to those values obtained by statistical analysis.
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seismic Moment Distribution revisited i statistical results
Geophysical Journal International, 2002Co-Authors: Yan Y. KaganAbstract:SUMMARY An accumulation of seismic Moment data gathered over the previous decade justifies a new attempt at a comprehensive statistical analysis of these data: herein, more rigourous statistical techniques are introduced, their properties investigated, and these methods are employed for analysis of large modern data sets. Several theoretical Distributions of earthquake size (seismic Moment‐frequency relations) are described and compared. We discuss the requirements for such Distributions and introduce an upper bound or a ‘corner Moment’ for a Distribution to have a finite energy or Moment flux. We derive expressions for probability density functions and statistical Moments of the Distributions. We also describe parameter evaluation, in particular how to estimate the seismic Moment Distribution for the largest earthquakes. Simulating earthquake size Distributions allows for a more rigourous evaluation of Distribution parameters and points to the limitations of the classical statistical analysis of earthquake data. Simulations suggest that several earthquakes approaching or exceeding the corner magnitude (mc) limit need to be registered to evaluate mc with reasonable accuracy. Using the Harvard catalogue data, we compare Moment Distribution parameters for various temporal spans of the catalogue, for different tectonic provinces and depth ranges, and for earthquakes with various focal mechanisms. The statistical analysis suggests that the exponent b is universal (b=0.60‐0.65) for all moderate earthquakes. The corner Moment (Mc) value, determined by the maximum-likelihood method, both in subduction zones and globally, is about 10 21 N m, corresponding to the corner Moment magnitude mc#8.0. For midoceanic earthquakes, mc is apparently smaller for spreading ridges, it is about 5.8, and for strike-slip earthquakes on transform faults it decreases from 7.2 to 6.5 as the relative slip velocity of faults increases. We investigate the seismic Moment errors, both random and systematic, and their dependence on earthquake size. The relative errors seem to decrease for larger events. The influence of Moment uncertainties on the parameter estimates is studied. Whereas the b values do not appear to be significantly influenced by the errors, for the corner Moment large errors can lead to substantially biased estimates. We compare the Harvard catalogue results with the earthquake data from instrumental catalogues in the first three-quarters of the 20th century. Several very large earthquakes (mi9) occurred around the middle of the century. Their magnitude values cannot be fitted by a modified Gutenberg‐Richter law with mc=8.0‐8.5. Among other factors, this discrepancy can be explained by either substantially higher errors in the earlier magnitude values, or by mc being higher for some subduction zones. It is unlikely that data available presently or soon will be sufficient to determine the corner magnitude of 9 and above, with reasonable precision, using purely statistical methods.
Daisuke Mizuno - One of the best experts on this subject based on the ideXlab platform.
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atomic dipole Moment Distribution on a hydrogen adsorbed si 111 7 7 surface observed by noncontact scanning nonlinear dielectric microscopy
Applied Physics Letters, 2013Co-Authors: Daisuke Mizuno, Kohei Yamasue, Yasuo ChoAbstract:Noncontact scanning nonlinear dielectric microscopy (NC-SNDM) can atomically resolve the polarization Distribution on material surfaces. We observed a hydrogen-adsorbed Si(111)–(7 × 7) surface using NC-SNDM and found that hydrogen-adsorbed Si adatoms had lower dipole Moments than bare Si adatoms. We discuss the charge Distribution around a hydrogen-adsorbed Si adatom in terms of its geometry and the electronegativities of hydrogen and silicon. Our model suggests that the charge Distribution around a hydrogen-adsorbed adatom is nearly symmetric and it qualitatively explains the experimental results. We thus conclude that the hydrogen-adsorbed Si adatoms are both electrically and chemically passivated.