The electron mobility and the static dielectric constant of Cd3As2 at 4.2 K

The ionized-impurity mobility of Cd₃As₂ at 4.2 K with carrier concentration lying in the range 10¹⁸–10¹⁹ cm^?3 has been calculated taking into account the inverted HgTe-type energy band structure of this material. A comparison of the results with experimental mobility data leads to a static dielectric constant of ?₀ = 36. This value represents a lower limit since any compensation effects would increase the fitted estimate of ?₀.     

Specific heat of the semiconducting layered compound SnSe2 at low temperatures

The specific heat of the layer compound semiconductor tin diselenide SnSe₂ has been measured in the temperature range from 2.7 to 280 K. In this range, the overall temperature dependence of the specific heat is dominated by the lattice contribution, which yields a limiting Debye characteristic temperature at absolute zero θ_D (0) = 140 ± 2K. The increase in the specific heat at low temperatures is more gradual than what would be expected for a simple Debye solid, and reflects the quasi-two dimensional layer structure of this compound.     

Calculation of the transmission coefficient of low-energy (<20 eV) electrons at the surface potential barrier of a metal

A simple approximation method is developed for calculating the quantum-mechanical transmission coefficient T(E) of a slow electron (in the energy range E < 20 eV) for the case of a one-dimensional surface potential barrier model which simulates most closely the real shape of the potential acting on an electron at a metal-vacuum interface. Although this method is developed for this particular case, it should permit, in principle, the direct investigation of arbitrary potential-energy functions.     

High-LET radiolysis of liquid water with 1H+, 4He2+, 12C6+, and 20Ne9+ ions: effects of multiple ionization

Monte Carlo simulations are used to investigate the effects of multiple ionization of water molecules on the yields of formation of free radical and molecular species, including molecular oxygen, in the radiolysis of pure, deaerated liquid water by using different types of radiation (1H+, 4He2+, 12C6+, and 20Ne9+ ions) up to approximately 900 keV/microm, at neutral pH and 25 degrees C. Taking into account the double, triple, and quadruple ionizations of water, the primary (or "escape") yields (at 10(-6) s) of the various radiolytic species (G(e(aq)-), G(H*), G(H2), G(*OH), G(HO2*/O2*-), and G(H2O2) are calculated as a function of the linear energy transfer (LET) of the radiation. Our results quantitatively reproduce the large increase observed in G(HO2*/O2*-) at high LET. Under the conditions of this study, the mechanisms of triple and quadruple ionizations contribute only weakly to the production of HO2*/O2*-. With the exception of protons, our calculations also simultaneously predict a maximum in G(H2O2) corresponding to the LET of approximately 4.5-MeV helium ions (approximately 100 keV/microm) and approximately 110-MeV carbon ions (approximately 180 keV/microm). This maximum occurs where G(HO2*/O2*-) begins to rise sharply, suggesting, in agreement with previous experimental data, that the yields of HO2*/O2*- and H2O2 are closely linked. Moreover, our results show a steep increase in the initial and primary yields of molecular oxygen with increasing LET, giving support to the "oxygen in heavy-ion tracks" hypothesis. By contrast, it is found that, in the whole LET range considered, the incorporation of multiple ionization in the simulations has only little effect on the variation of our computed G(e(aq)-), G(H*), G(H2), and G(*OH) values as a function of LET. As expected, G(e(aq)-) and G(*OH) decrease continuously with increasing LET. G(H*) at first increases and then decreases at high LET. Finally, G(H2) monotonically rises with increasing LET. Our calculated yield values compare generally very well with experiment.     

Electron mean free path and conduction-band density-of-states in solid methane as determined from low-energy electron transmission experiments

Recently, Plenkiewicz et al. developed a theoretical model for analyzing the current I_t transmitted by a thin dielectric film as a function of incident electron energy E. The purpose of this paper is to apply this model to the analysis of recent I_t(E) results for solid methane. The analysis permits the determination of both the electron mean free path as a function of energy and the electronic conduction-band density-of-states in the quasi-elastic scattering region. The differences between our results and Kunz's solid methane band structure calculations are also discussed.     

Specific heat of pure graphite in the ultra-quantum limit region

We calculate the electronic specific heat of pure graphite in the ultraquantum limit region for fields between 60 and 200 kG, at very low temperatures, using the Slonczewski-Weiss band model with values of the energy-band parameters which are in agreement with recent magneto-replection experiments. The effect of trigonal warping of the Fermi surfaces associated with the parameter γ₃ is neglected in the calculation. Our results show that, for most of the range of fields considered, the electronic specific heat C is very nearly proportional to both the magnetic field strength H and the temperature T, according to the relation C ≈ αHT with a coefficient α of about 0.091 μJ/g-at. K²kG. The results also indicate that, at the upper end of the magnetic field range, the C(H) curves, at a given T, depart slightly and progressively from linearity with increasing H, essentially as a result of the variation of the Fermi energy with magnetic field.     

A note on the study of the thermomagnetic effects in graphite at low temperatures

The present paper is devoted to the study of the thermomagnetic effects, namely the thermoelectric power, S(H), and the Nernst-Ettingshausen coefficient, A_NE(H), in graphite at low temperatures and in the presence of small magnetic fields (H ? 15 kG). It is shown that the theory developed by Jay-Gerin and Maynard and by Jay-Gerin, on the basis of the phonon-drag effect in graphite, predicts a numerical estimate of S(H) and A_NE(H) which is in good agreement with the recent, though preliminary, experimental results of Takezawa, Mangez, Hewes, Dresselhaus and Tsuzuku. The need for a complete experimental analysis of all of the thermo-galvanomagnetic transport coefficients, taken on the same sample of graphite, over a wide range of magnetic fields and temperatures, is emphasized.