The turbulence of capillary waves on the surface of liquid hydrogen

It is experimentally demonstrated that the surface excitation of liquid hydrogen at a low frequency results in the turbulent mode in a system of capillary waves. The experimental results are in good agreement with the theory of weak wave turbulence. The pair correlation function of the surface deviations is described by the exponential function ω^m. The exponent m decreases in magnitude from m=?3.7±0.3 to ?2.8±0.2 when the pumping at a single resonant frequency changes to broadband noise excitation. Measurements are made of the dependence of the boundary frequency ω_b of the upper edge of the inertial range in which the Kolmogorov spectrum is formed on the wave amplitude η_p at the pumping frequency. It is demonstrated that the obtained data are well described by a function of the form ω_b∝η _p ^4/3 ω _p ^23/9 .     

Determination of the g-factor of electrons in N-type silicon surface inversion layers

The g-factor of conduction electrons in the surface inversion layer on a silicon (100) surface has been determined using the tilted magnetic field method developed by Fang and Stiles.The value of (m¹/m₀)·g at the fixed magnetic field was independent of surface carrier density n_s, whereas it had a sharp peak at about 97 koe. At strong magnetic field limit the value was constant and 0.4. If we take the effective mass of conduction electrons in the inversion layer on the (100) surface as 0.2m₀, the g-factor is about two which is the same as that for conduction electrons in bulk silicon.     

Shubnikov-de Haas effects in Bi2Se3 with high carrier concentrations

Shubnikov-de Haas frequencies were measured in highly degenerate n-type Bi₂Se₃ having a higher carrier density (～9 × 10²⁵m^-3) than previously reported. The Fermi surface was found to be elongated along the trigonal axis, fitting a spheroidal model with an axial ratio of 5.0 for angles up to θ = 45°. Comparison of the number of carriers obtained from Hall measurements with that obtained from the Shubnikov-de Haas measurement supports the contention that the lowest conduction band minimum is a single surface located in the center of the Brillouin zone. The higher effective mass (0.25 m₀) found for these carrier concentrations indicates that the band is non-parabolic.     

Evolution of a turbulent cascade on the surface of liquid hydrogen under a change in the spectral characteristic of an exciting force

The modification of the turbulent cascade in a system of capillary waves on the surface of liquid hydrogen under a change in the spectral width of exciting noise has been experimentally studied. The correlation function I _ω of the deviations of the surface of liquid hydrogen from equilibrium under broadband excitation is a monotonically decreasing function of frequency. The distribution I _ω in the inertial range is well described by the power function ω^?m with the exponent m close to 17/6. In the presence of narrowband excitation, a chain of peaks appears on the cascade I _ω; the positions of the peaks are described by a power function of frequency with the exponent m = 3.8 ± 0.1.     

Measurement of the surface density of states by field ionization

It is shown that recent measurements of field ion energy distributions from clean tungsten surfaces probe the density of metal states in the vicinity of the surface. We find j(ω) = (2π/kh)Σ_m| ∫ d³rψ_m(r)γ_z|²δ(ω??_m), where j(ω) is the ion current a ω, ψ_mand ?_m are electronic metal eigenfunctions and eigenvalues in the presence of the external electric field used in field ionization and γ(z) is a function which is large near the noble gas atom. An explicit expression for γ(z) is given in the text. It is estimated that tungsten metal states with values of k₆ at least as large as 0.5 Å^?1 make an appreciable contribution to j(ω) where k₆ is the electron momentum parallel to the surface.     

Study of mercury surface diffusion on tantalum with and without an electric field by means of a field emission microscope

The surface diffusion of mercury atoms on tantalum substrate with and without high electric field was studied by means of a field emission microscope (Müller's). The activation energy during surface migration Q_m of mercury atoms with and without an electric field F on tantalum substrate depending on the thickness of the adsorbate was measured. It is shown that the electron density distribution at coverage θ < 0.65 with adsorbate is due to a dipole momentum P. At θ > 0.65 the slope of the curves of Q^F_m = ?(θ) is explained with the appearance of the effect of polarization. The energy of desorption Q_d as a function of the thickness of the adsorbed layer in the temperature range 100–300 K was measured also.     

纳米金属Tm的电子浓度研究

电子浓度是与金属的宏观特性相关的重要参数.反射光谱和霍尔效应分别是得出电子浓度和载流子浓度的基本实验.两个纳米稀土金属铥Tm样品(样品1,平均粒径100nm,样品2,平均粒径10nm)的红外---紫外反射光谱实验表明,金属铥Tm表面的反射光学性质具有金属的特征,6s能带具有与碱金属相近的电子浓度n_p,数值分别为2.434×10²⁸/m³和1.701×10²⁸/m³.而样品的霍尔效应实验测得金属Tm的载流子是电子-空穴型的,载流子浓度n_H仅分别为8.032×10²⁴/m³和7.679×10²⁴/m³,仅仅是费米面附近的电子-空穴状态.另外,铥Tm的电导率比半导体的大3个量级.晶粒纳米化使电子浓度n_p减小,电导率σ减小,载流子浓度减小,而霍尔系数R_H增大.     

Particle production in a slowly alternating electric field

The spectral density of particles produced in a slowly alternating electric field E(t) is calculated. At m²/|eE|?1 the field can be considered as constant, provided |?/E| ? m(|eE|/m²)^{$\text{3}\text{2}$}.     

Light quarks mass effect on the color ferromagnet model of the QCD vacuum

We study the effect of quark masses on the energy density of two ferro-magnetic vacua in QCD, corresponding to different vacuum symmetries. In the massless limit the two states have the same energy, while as the quark masses are turned on the state with more symmetry elements becomes the “true” vacuum. The dominant contribution to the energy density splitting is proportional tom ² lnm ²     

Space-time curvature due to quantum vacuum fluctuations: An alternative to dark energy?

It is pointed out that quantum vacuum fluctuations may give rise to a curvature of space-time equivalent to the curvature currently attributed to dark energy. A simple calculation is made, involving plausible assumptions within the framework of quantized gravity, which suggests that the value of the dark energy density is roughly given by the product of Newton's constant times the quantity m⁶c⁴?−4, m being a typical mass of elementary particles. The estimate is compatible with observations.     

Computational study of the surface properties of aluminum nanoparticles

We calculate the surface energy, surface stress, and lattice contraction of Al nanoparticles using ab initio density functional and empirical computational techniques. Ab initio calculations are carried out using the siesta pseudopotential method combined with the generalized gradient approximation. Empirical calculations are conducted using the embedded atom method. The ab initio density functional approach predicts the surface energies of Al nanoclusters to be in the range of 0.9-2.0 J/m². These values are consistent with the surface energy of bulk aluminum and are close to the surface energies of silver nanoparticles calculated in our previous study. In contrast to our previous results for Ag nanoparticles, we found a significant discrepancy between the theoretical values of surface energy and stress for Al nanoclusters. This result could be explained by a greater degree of surface reconstruction in Al clusters than in Ag clusters.     

Effects of thermal light source properties in two-photon subwavelength coincidence interference experiments

We perform two-photon coincidence subwavelength interference experiments from double slit using independent photons obtained from a pseudo-thermal light source produced by (i) slowly rotating ground glass (RGG) with turbid solution of a different density and (ii) RGG. The turbid solution is water solution containing 3 μm diameter polystyrene microspheres. It is found that the visibility of the obtained interference pattern decreases in first experiment with increasing the density of the turbid solution from N = 10¹⁰ spheres m⁻³ to N = 10¹⁴ spheres m⁻³. However, the results are reported here for the density of N = 10¹⁴ spheres m⁻³. The visibility obtained with RGG with turbid solution having N = 10¹⁴ spheres m⁻³is 23% which increases to 27% with RGG but the resolution decreases. The effect of coherence width of source in two-photon interference pattern is also studied with pseudo-thermal light obtained by RGG. It was observed that on increasing the coherence width the visibility of interference fringes increased and quality of the fringe reduced and when the coherence width was more then slit separation, in coincidence measurements, no interference pattern appeared. The results are used to explore the classical subwavelength interference nature with thermal light.     

Surface self-diffusion studied by microscopic measurements of crystallite profile evolutions

Dendritic gold crystallites on graphite are heated in ultra high vacuum up to less than 0.5 of the melting point (T_m). Electron microscopy shows that the gold crystallites change their shapes by surface self-diffusion. The dendritic contours round off while the crystallite remains very flat (20 to 40 Å). The increase with time of the radii of dendrite tips is measured statistically. Such an evolution can be described by analogy to the blunting of either metal tips (Nichols and Mullins) or monoatomic cleavage tips (Höche and Bethge). Using this result, a new technique to measure surface self-diffusion coefficients (D) is proposed. Test measurements have shown that this is an interesting, very sensitive method to measure D (down to 10^?13 cm^?2 s^?1) which enables measurements to be made in an unusual low temperature range (0.25 T_m < T < 0.5T_m). In special cases the dendrites are split by the surface self-diffusion which is qualitatively in agreement wih the theory.     

Effect of interband scattering on kinetic coefficients and estimates of the parameters of the band spectrum of Sb2Te3

It has been shown that uncertainties in the interpretation of experimental data on transport phenomena in Sb₂Te₃ are resolved in the two-band model with the consistent inclusion of the interband hole scattering. The performed calculation is in quantitative agreement with the experimental data in the temperature range from 77 to 400 K for the following parameters of the band spectrum: the effective mass of the density of states of light holes m _d1 ≈ 0.6m ₀ (where m ₀ is the free electron mass), the effective mass of the density of states of heavy holes m _d2 ≈ 1.8m ₀, and the energy gap between nonequivalent extrema of the valence band ΔE _v(T) ≈ 0.15–2.5 × 10^?4 T eV.     

Molecular binding states on clean and oxidized surfaces: SiO(g) + W(clean) and SiO(g) + W(oxidized)

The interactions between a molecular beam of SiO(g) and a clean and an oxidized tungsten surface were examined in the surface temperature range 600 to 1700 K by mass spectrometrically determined sticking probabilities, by flash desorption mass spectrometry (FDMS) and by Auger electron spectroscopy (AES). The sticking probability, S, of SiO has been determined as a function of coverage and of surface temperature for the clean and the oxidized tungsten surface. Over the temperature range studied and at zero coverage S = 1.0 and 0.88 for the clean and oxidized tungsten surfaces respectively. The results are consistent with both FDMS and AES. For coverage up to one monolayer there is one major adsorption state of SiO on the clean tungsten surface. FDMS shows that T_m = constant (T_m is the surface temperature at which the desorption rate is maximum) and that desorption from this state is described by a simple first order desorption process with activation energy, E_d = 85.3 kcal mole^?1 and pre-exponential factor, ν = 2.1 × 10¹⁴ sec^?1. AES shows that the 92 eV peak characteristic of silicon dominates. In contrast on the oxidized tungsten surface, T_m shifts to higher temperatures with increasing coverage. The data indicate a first order desorption process with a coverage dependent activation energy. At low coverage (θ ? 0.14) there is an adsorption state with E_d = 120 kcal mole^?1 and ν = 7.6 × 10¹⁹, while at θ = 1.0, E_d = 141 kcal mole^?1. This variation is interpreted as due to complex formation on the surface. AES shows that on oxidized tungsten, in contrast to clean tungsten, the dominant peaks occur at 64 and 78 eV, and these peaks are characteristic of higher oxidation states of silicon. Thus, it is concluded that SiO exists in different binding states on clean and oxidized tungsten surfaces.     

Exchange and correlation potentials in the one-electron equation

The self-energy operator of an electron liquid is examined by including the particle-hole and particle-particle ladder types of vertex corrections to the simplest approximation discussed by Hedin and Lundqvist. It is found that the real part of the self-energy correction ∑(p, ε_p) is much more independent of the wavenumber p than that in the simplest approximation because of the strong short-range correlations at metallic densities. The quasi-particle mass ratio m¹/m in the present approximation gives values smaller than 1 in the whole metallic density region.     

New resonance-polariton Bose-quasiparticles enhances optical transmission into nanoholes in metal films

We argue the existence of fundamental particles in nature, neutral Light-Particles with spin 1, and rest mass m=1.8⋅¹⁰−4me, in addition to electrons, neutrons and protons. We call these particles Light Bosons because they create the electromagnetic field which represents Planck's gas of massless photons together with a gas of Light-Particles in the condensate. In this respect, the condensed Light-Particles, having no magnetic field, represent the constant electric field. In this context, we predict an existence of polariton-plasmon Bose-quasiparticles with effective masses ml≈¹⁰−6me and mr=0.5me, which are induced by interaction of the plasmon field and the resonance Frölich-Schafroth charged bosons with electromagnetic wave in metal. Also, we prove that the enhancement optical transmission into nanoholes in metal films and Surface Enhanced Raman Spectroscopy are provided by a new resonance-polariton Bose-quasiparticles but not model of surface plasmon-polariton. In this Letter, the quantization Fresnel's equations is presented which confirms that Light-Particles in the condensate are concentrated near on the wall of grooves in metallic grating and, in turn, represent as the constant electric field which provides the launching of the surface Frölich-Schafroth bosons on the surface metal holes.     

Thermomagnetic writing on deep submicron-patterned TbFe films by nanosecond current pulse

This work studies the heating process for deep submicron-patterned TbFe films to be used in a thermally assisted perpendicular magnetic random access memory's writing scheme. The dependence of the heating power density with the current pulse width required for the successful writing was measured in the investigated range of 5-100 ns. In the case of long current pulse, the heat diffuses dominantly into substrate, which resulted in large variation of the required power/energy density with the patterned size. The power/energy densities required for writing increased as the junction area is reduced. While for the short current pulse width, the power/energy densities became rather independent on the size. The required power density for writing 0.38×0.28 μm² patterned films using the pulse width of 5 ns is experimentally estimated to be around P=4.7 mW/μm², corresponding to the energy density of E=23 pJ/μm², under an external field of 100 Oe.     

Sputtering of metals at ion-electron irradiation

It has been found that, in contrast to the commonly accepted opinion, simultaneous irradiation by 15-keV Ar⁺ ions and 2.5-keV electrons at temperatures above 0.5T _m (T _m is the melting temperature) induces much larger sputtering of metallic copper, nickel, and steel than irradiation only by Ar⁺ ions. The effect increases with the temperature. At T = 0.7T _m, the sputtering coefficients in the case of ion-electron irradiation are more than twice as large as the sputtering coefficients in the case of irradiation by Ar⁺ ions. The experiments on the sublimation of copper show that the sublimation rate in the case of the heating of a sample by an electron beam is higher than that in the case of heating in an electric vacuum oven. The revealed effects are explained by the electron-induced excitation of adatoms (atoms stuck over the surface, which appear owing to ion bombardment). Excited adatoms have a smaller binding energy with the surface and are sputtered more easily.     

Analytic study of chaos of the tent map: Band structures,power spectra,and critical behaviors

Chaotic behaviors of the tent map (a piecewise-linear, continuous map with a unique maximum) are studied analytically throughout its chaotic region in terms of the invariant density and the power spectrum. As the height of the maximum is lowered, successive band-splitting transitions occur in the chaotic region and accumulate to the transition point into the nonchaotic region. The timecorrelation function of nonperiodic orbits and their power spectrum are calculated exactly at the band-splitting points and in the vicinity of these points. The method of eigenvalue problems of the Frobenius-Perron operator is used. 2 ^m?1 critical modes, wherem = 1,2, 3, ..., are found which exhibit the critical slowing-down near the 2 ^m?1-band to 2 ^m -band transition point. After the transition these modes become periodic modes which represent the cycling of nonperiodic orbits among 2 ^m bands together with the periodic modes generated by the preceding band splittings. Scaling laws near the transition point into the nonchaotic region are investigated and a new scaling law is found for the total intensity of the periodic part of the spectrum.