Millimeter wave dispersion in ethyl chloride

Dispersion of millimeter waves due to ethyl chloride in the range ν=1·34 cm^?1 to 1·44 cm^?1 is computed by means of quantum mechanical formulas. It is found that dispersion is due to (i) contribution of sixR branch rotational lines in the region considered, (ii) contribution ofR branch lines away from the region and (iii) the contribution ofQ branch lines at zero wavenumber. The maximum variation in the susceptibility is 1·9 × 10^?5 and occurs at ν=1·39 cm^?1 due to combined contribution of transitions at 1·3878 cm^?1, 1·3902 cm^?1 and 1·3927 cm^?1.     

Wavelength-dependent susceptibility of iron in the critical region

Two-axis spectrometer neutron scattering data on iron are re-analysed in the light of recent results on the spin relaxation near T_c. There is no evidence for any boundary of the hydrodynamic region from the behaviour of χ(q). The q- and T-dependence of χ(q) in the critical region q ⪢ k₁ give arguments for a non-zero value of the critical exponent η.     

Raman spectroscopy of thallium chloride in the melting region

We have followed the temperature dependence of the second order Raman spectra of b.c.c. thalliumchloride crystals and polycrystalline powders with particular regard to the region immediately preceding and following melting. Our results, concerning mainly the behavior of the LA(X)-TA(X) peak, imply the appearance of a new damping mechanism for the TA(X) phonon approximately 10°C below the melting temperature. Furthermore, this conjecture seems to be supported by calorimetric measurements near melting.     

Electric charge on dislocation arrays in sodium chloride

The electric charge on dislocation arrays was studied as a function of temperature by observing the displacement of pure tilt low angle grain boundaries in sodium chloride bicrystals maintained in an electric field. The sign of the charge was determined unambiguously by direct observation of the boundary displacement relative to the polarity of the electric field; the existence of an isoelectric point was confirmed. No measurable boundary displacement is found below a certain (threshold) value of electric field which depends on temperature. For larger fields boundary migration is observed to occur with no delay in time and at a uniform rate which increases monotonically with increasing field. The method used permits the determination of the driving force on the boundary and of the migration velocity as two independent quantities ; from the temperature dependence of the boundary mobility thus determined an activation energy for the process was obtained.     

A new electronic transition of antimony chloride in the visible region

The emission spectrum of SbCl has been photographed at high resolution in the region 400 to 640 nm. In addition to bands of two previously reported transitions in this region, A₁-X and A₂-X, 36 bands of a new system have been identified. A vibrational analysis has been made with ν₀₀ ≈ 20 679 cm⁻¹, and 7 of the bands have been rotationally analyzed. The electronic transition has ΔΩ = 0 with lower state constants which match published data for the ground state X³Σ⁻(0⁺). The upper state is characterized by the following ¹²¹Sb³⁵Cl molecular parameters: B′₀ = 0.0922 cm⁻¹, D′₀ = 3.1 × 10⁻⁸ cm⁻¹.     

Equipment for the automatic recording of paramagnetic absorption on centimetre waves

The paper briefly describes equipment for the automatic recording of paramagnetic absorption on centimetre waves in the 3 cm band. The instrument automatically adjusts the frequency of the high-frequency generator to the resonant frequency of the cavity resonator containing the material being tested. The sensitivity of the equipment is increased by using bridge connection.     

The static generalized susceptibility for a ferromagnet in the critical region

A method of calculating the static generalized susceptibility for the critical region in the constant coupling approximation has been formulated and applied to ferromagnets above the Curie point, leading to an anisotropic susceptibility.     

Ac susceptibility of NdFeO3 in the spin reorientation region

The temperature dependence of real and imaginary components of ac susceptibility as well as of nonlinear susceptibility and of the hysteresis loop have been measured for polycrystalline NdFeO₃ in the range 78–315 K. The measurements were performed at various amplitudes of the ac field and in the presence of a constant magnetic field. The double ac technique was also used to measure the field dependence of susceptibility. The complicated temperature and field dependence of susceptibility was found for NdFeO₃ in the spin reorientation region (103–165 K).     

聚焦高斯涡旋光束焦区电场和磁场的偏振奇点

以高斯涡旋光束为例,研究了聚焦场中电场和磁场的偏振奇点变化规律.结果表明,高斯涡旋光束经透镜聚焦后,在焦区存在二维和三维电场和磁场的偏振奇点,其位置一般不重合.适当改变与焦面的距离以及光阑截断参数等出现圆偏振奇点的移动、产生和湮没.不同二维和三维电场和磁场圆偏振奇点湮没所对应的各参数临界值不同.在二维电场中,几何焦面上会有V点的产生.     

Diode laser spectroscopy of the ν9 band of ethyl chloride

The vibration-rotation spectrum of the ν₉ band of C₂H₅Cl was recorded using a Nicolet 7199 Fourier Transform Infrared Spectrometer; the Q-branch, R(5)-R(6) multiplets, and P(21)-P(22) multiplets were investigated using a tunable semiconductor diode laser spectrometer. Constants derived from these assignments are (cm^?1) ν₉ = 973.8379(2), A⁹ = 1.039516(3), B⁹ = 0.183081(7), C⁹ = 0.164505(8). The line which coincides with the CO₂ laser 10R(6), which has been employed in multiphoton dissociation studies, is tentatively assigned to the 20_{3 18}-21_{3 19} transition. In addition, a very strong coincidence of transitions 19_{9 11}-19_{9 10} and 19_{9 10}-19_{9 11} with the CO₂ 10R(16) line is found, which can provide a good candidate for laser chemistry and infrared double resonance spectroscopy.     

An improved technique for the measurement of the complex susceptibility of magnetic colloids in the microwave region

Measurements by means of the short-circuit (S/C) and open circuit (O/C) transmission line techniques are well established methods for investigating the magnetic and dielectric properties of magnetic colloids, respectively. In particular, the S/C technique has been used in the investigation of the resonant properties of ferrofluids; resonance being indicated by the transition of the real component of the magnetic complex susceptibility, χ(ω)=χ′(ω)−iχ″(ω), from a positive to a negative value at a frequency, f_res. However, under certain circumstances, the accuracy of the S/C technique is affected by the dielectric properties of the sample, hence incurring errors in the measurement of χ(ω) and indeed of f_res. Here we present a model which, by combining short-circuit and open circuit measurements, is developed in a manner in which the permeability, μ, and the permittivity, ε, contribute simultaneously to the calculation of χ(ω), thereby providing superior experimental results in comparison to those obtained by the S/C technique alone. For the two ferrofluid samples measured it is demonstrated that the dielectric properties affect the high frequency content of the susceptibility spectrum.     

Electric field of a buried interfacial region measured by positron-lifetime spectroscopy

Positrons from a radioactive source are implanted into a reverse-biased metal–semiconductor contact and are drifted back towards the contact by the internal electric field where they trap into voids and annihilate. The electric field dependent interface annihilation fraction is monitored by way of the intensity of the long (∼400–500 ps) void lifetime component using positron-lifetime spectroscopy. Unlike previous analyses of such systems a numerical model involving positron drift, annihilation and trapping into the interfacial state has been constructed to describe the positron dynamics in the presence of the non-uniform junction electric field. The use of the positron-lifetime technique in probing the internal electric field at buried contacts is thus demonstrated. Results obtained using the numerical method for the Au, Al and Ni/Semi-Insulating (SI)-GaAs contact systems are found to be consistent with the findings of previous studies on the Au/SI-GaAs system. Received: 29 November 2000 / Accepted: 26 February 2001 / Published online: 25 July 2001     

Dynamical spin susceptibility of the d–p model in the over doping region

Dynamical spin susceptibility χ^s(q,ω) of the d–p model in the over doping region is investigated by using the auxiliary boson technique. It includes higher order terms of the 1/N-expansion within the random phase approximation (RPA) of the local vertex, where frequency dependence of the quasi-particle interaction is taken into account. The incommensurate spin fluctuation is obtained due to the nesting effect in the low energy region (ωω^*), whereas the commensurate one in the high energy region (ωω^*), the characteristic energy ω^* is estimated to be about 30 meV. Both of the spin–lattice relaxation rate 1/T₁ and the spin–spin relaxation rate 1/T_g monotonically increase as T decreases, while the spin Knight shift K is almost independent of T.     

Electric field dependence of the dielectric susceptibility in K1−xLixTaO3

Results are presented for the dielectric function $\text{ε1 = ε}{}_1\text{+ iε}{}_2$ in K_1?xLi_xTaO₃ in the frequency range 10 < f < 10⁶ Hz and for several fields. The data are analysed in terms of dielectric relaxation, and it is shown that the electric bias field modifies the relaxation behaviour drastically.     

Mössbauer,EPR and susceptibility studies of highly conducting polypyrrole doped with iron chloride

The results of Mössbauer, EPR and static magnetic susceptibility measurements on polypyrrole doped with FeCl₃ are presented. They indicate that iron chloride tetrahedra are interacting with the polymer matrix by hydrogen bonding. This interaction increases with dehydration of the samples. The susceptibility showed a maximum near 5 K, which is an indication for antiferromagnetic interaction, probably between paramagnetic iron and polarons.     

Investigation of the motion kinetics of screw dislocations in sodium chloride and potassium chloride crystals

The kinetics of the motion and the surmounting of detents by dislocations in sodium chloride and potassium chloride crystals is investigated herein. Special attention is paid to a comparative study of the mean free paths of the screw and edge dislocations. It is established that the mean free paths of the screw dislocations is somewhat less than for edge dislocations under identical test conditions. The kinetic curves obtained were processed within the frame-work of theoretical representations about the motion of dislocations in crystals containing detents of two kinds.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 16, No. 9, pp. 17–21, September, 1973.