Measurement of magnetostriction and anisotropy of Mg-ferrite

The magnetostriction constants λ₁₀₀ and λ₁₁₁ and the anisotropy constant K₁ of Mg-ferrites [Mg_η;Fe_1?η][Mg_1?ηFe_1+η]O₄, (η = 0·101, 0·154, 0·184, 0·219) at room temperature, liquid N₂ temperature and liquid He temperature were observed by ferrimagnetic resonance techniques at 9·5 GHz.The signs of the magnetostriction constants λ₁₀₀ and λ₁₁₁ are always negative and positive, respectively and the magnitudes of these constants increase with decreasing temperature. These constants λ₁₀₀ and λ₁₁₁ at liquid He temperature are found to be ? 14·4 × 10^?6 and 2·4 × 10^?6 respectively, when η is 0·101, and then the magnitudes of those constants decrease linearly with increasing η.     

Magnetostriction measurements of Ni-Zn ferrite single crystals

The magnetostriction constants λ₁₀₀ and λ₁₁₁ of Ni-Zn ferrite Ni_1?xZn_xFe₂O₄ single crystals with x equal to 0, 0.07, 0.17, 0.40 and 0.67 were measured by a three terminal capacitance method from liquid N₂ to room temperatures.The constants λ₁₀₀ and λ₁₁₁ of Ni ferrite at liquid N₂ temperature were ?43.0 × 10^?6 and ?20.1×10^?6 respectively.The magnitude of the constant λ₁₀₀ increased with the increase of Zn concentration and took a maximum at x of about 0.33, while the magnitude of the constant λ₁₁₁ decreased almost linearly with the increase of Zn concentration and then became zero at x about 0.75.     

Tunable laser study of the ν10 + ν11 band of cyclopropane

Diode laser measurements of the ν₁₀ + ν₁₁ (l_tot = ±2) perpendicular band of cyclopropane have led to the assignments of roughly 600 lines in the 1880–1920-cm^?1 region. Most of the spectra were recorded and stored in digital form using a rapid-scan mode of operating the laser. These spectra were calibrated, with the aid of a computer, by reference to the R lines of the ν₁ + ν₂ band of N₂O. The ground state constants we obtained are (in cm^?1) B = 0.670240 ± 2.4 × 10^?5, D_J = (1.090 ± 0.054) × 10^?6, D_JK = (?1.29 ± 0.19) × 10^?6, D_K = (0.2 ± 1.1) × 10^?6. The excited state levels are perturbed at large J values, presumably by Coriolis couplings between the active E′(l_tot = ±2) and the inactive A′(l_tot = 0) states. Effective values for the excited state constants were obtained by considering only the J < 15 levels. The A₁-A₂ splittings in the K′ = 1 excited states were observed to vary as q_effJ(J + 1), with q_eff = (2.17 ± 0.17) × 10^?4 cm^?1.     

Kinetic mechanisms of the uptake of atmospheric gases on the surface of sea salts. ClNO3 uptake on MgCl2 · 6H2O/NaCl

The uptake coefficients γ of chlorine nitrate on MgCl₂ · 6H₂O crystallites and a MgCl₂ · 6H₂O-NaCl mixture deposited from an aqueous solution are measured using a flow reactor with a movable salt-substrate-coated insert equipped in combination with a mass spectrometer at 295–428 K, [ClNO₃] = (0.2?12) × 10¹² cm^?3, and [H₂O] = 1.0 × 10¹² ? 4.3 × 10¹⁵ cm^?3. Immediately after the exposure of the salt substrate to a ClNO₃ flow, γ(t) decreases exponentially with time, γ(t) = γ₀ × exp(?t/τ) + γ _s , to a steady-state level, γ _s , which depends on the temperature and the ClNO₃ and H₂O concentrations. The main gas-phase product is Cl₂, HOCl appears only when water vapor is admitted into the reactor. The coefficient of steady-state uptake on wetted MgCl₂ · 6H₂O at 295 K can be described by the approximation γ = a + b [H₂O] with a = 3.5 × 10^?3 cm³ and b = 3.2 × 10^?18 cm³. The mechanism of the uptake of ClNO₃ on MgCl₂ · 6H₂O is discussed. The experimental data are treated within the framework of a steady-state uptake model to estimate the heat of adsorption of ClNO₃ on MgCl₂ · 6H₂O (Q _ad = 62 kJ/mol) and the activation energy of the bimolecular heterogeneous reaction ClNO₃ + Z _s = 2Cl₂ + Mg(NO₃)₂ · 6H₂O (E _a = 21.8 kJ/mol; Z _s denotes a ClNO₃-MgCl₂ · 6H₂O surface complex). When the MgCl₂ · 6H₂O: NaCl is varied from 0 to ～3 wt %, the steady-state uptake coefficient changes from the value corresponding to uptake on pure NaCl to that characteristic of uptake on pure MgCl₂ · 6H₂O.     

The B 2Σ+–X 2Σ+ Transition of 12C17O+: The 2‐υ″ Progression

Abstract

Three new bands of the B ²Σ⁺–X ²Σ⁺ system of ¹²C¹⁷O⁺ have been investigated using conventional spectroscopic techniques. The spectra were observed in a graphite hollow‐cathode lamp by discharging molecular oxygen (enriched in about 45% of the ¹⁷O₂ isotope) under 1.0 Torr pressure. The rotational analysis of the 2–4, 2–5, and 2–6 bands was performed with the effective Hamiltonian of Brown (Brown et al., J. Mol. Spectrosc. 1979; 74: 294–318). Molecular constants were derived from a merge calculation, including both the current wavenumbers and the spectroscopic data published by the authors previously. The principal equilibrium constants for the ground state of ¹²C¹⁷O⁺ are ω_e=2185.9658(84), ω_e x _e = 14.7674(11), B _e=1.927001(38), α_e=1.8236(22)×10^?2, γ_e=?0.331(28)×10^?4, D _e=6.041(12)×10^?6, β_e=0.100(31)×10^?7 cm^?1, and the equilibrium constants for the excited state are σ_e=45876.499(15), ω_e=1712.201(12), ω_e x _e=27.3528(39), B _e=1.754109(35), α_e=2.8706(57)×10^?2, γ_e = ?1.15(19)×10^?4, D _e=7.491(20)×10^?6, β_e=2.13(12)×10^?7, γ_e = 2.0953(97)×10^?2, and α_γe=?9.46(59)×10^?4 cm^?1, respectively. Rydberg–Klein–Rees potential energy curves were constructed for the B ²Σ⁺ and X ²Σ⁺ states of this molecule, and Franck–Condon factors were calculated for the vibrational bands of the B–X system.     

Magneto-acoustic attenuation in AuSb2

Quantum oscillations in the ultrasonic attenuation in AuSb₂ were studied as a function of temperature, magnetic field and crystal orientation. The effective masses of the carriers associated with the F₅ and F₆ oscillations were measured in a (110) plane. For the F₅ oscillations, the Dingle temperature and apparent magnetic breakdown field appear to depend strongly upon orientation. For the F₆ oscillations, however, there were no signs of magnetic breakdown up to the highest magnetic fields available (70 kOe) and the Dingle temperature was roughly independent of orientation. From the acoustic velocities, the elastic constants were determined at 77 K: C₁₁ = (14·7 ± 0·9) × 10¹¹ dyne/cm², C₁₂ = (6·0 ± 0·9) × 10¹¹ dyne/cm², and C₄₄ = (2·59 ± 0·06) × 10¹¹ dyne/cm². These elastic constants give an adiabatic compressibility K_s = (1·13 ± 0·12) × 10^?12 cm²/dyne and a Debye temperature ?_D = (203 ± 15) K.     

Ferroelectric and optical properties of Ba6Ti2Nb8O30 single crystals

The dielectric, optical and non-linear optical properties of Ba₆Ti₂Nb₈O₃₀ single crystals were examined from room temperature up to the Curie temperature of 245°C. The spontaneous polarization at room temperature was estimated as 0·22±0·01 C/m². The linear electrooptic constants were measured as r₃₃^T=(1·17±0·02)×10^?10 and r₁₃^T=(0·42±0·01)×10^?10 m/V. The non-linear optical coefficients were d₃₃=(15·1±2·0)×10^?12 and d₃₁=(11·0±2·0)×10^?12 m/V, which are comparable to those of Ba₄Na₂Nb₁₀O₃₀. Temperature dependences of δ₃₃ and δ₃₁ (Miller's δ) were found to be proportional to that of P_s.     

Production and loss of N 2 + , Ne+ and Ne 2 + during the decay period of plasmas produced in neon-nitrogen mixtures

Studies of the time dependencies of the number density of N ₂ ⁺ , Ne⁺ and Ne ₂ ⁺ ions have been made during the decay period of plasmas produced in neon containing various concentrations of nitrogen molecules. Reaction rate constants were obtained for N ₂ ⁺ +N₂+Ne→N ₄ ⁺ +Ne((1.2±0.2)×10^?29 cm⁶ sec^?1) and Ne⁺+N₂→N ₂ ⁺ + Ne ((2.9±0.3) × 10^?12 cm³ sec^?1). The ambipolar diffusion coefficient of N ₂ ⁺ in neon was found to beD _a p _o =350±20 cm² sec^?1 Torr.     

The forced magnetostriction of nickel at 4.2 K

The forced volume magnetostriction of polycrystalline nickel at 4.2 K has been determined with a relative accuracy of 2 × 10^?2. Combining our result with previous data on the forced magnetostriction, we derive for the forced magnetostriction constants: h'₀ = (40 ± 1) × 10^?8T^?1, h'₁ = (-95 ± 2) × 10^?8T^?1, h'₂ = (-19 ± 2) × 10 ^?8T^?1.     

Spectral and nonlinear studies of an aniline blue dye in liquid and solid media

Solid-state dye-doped polymers are an attractive alternative to conventional liquid dye solutions. In this paper, the spectral characteristics and nonlinear properties of the Aniline Blue dye has been studied. The third-order nonlinear optical properties of the Aniline Blue dye in ethanol and a dye-doped polymer film were measured by the Z-scan technique using a 632.8-nm He-Ne laser. This material exhibits a negative optical non-linearity. The dye at a 0.4-mM concentration exhibited a nonlinear refractive coefficient (n ₂ = ?4.02 × 10^?8 and ?4.41 × 10^?8 cm²/W in liquid and solid media, respectively), a nonlinear absorption coefficient (β = ?9.7 × 10^?4 and ?11.63 × 10^?4 cm/W in liquid and solid media, respectively), and susceptibility (x ⁽³⁾ = 1.844 × 10^?6 and 2.028 × 10^?6 esu in liquid and solid media, respectively). These results show that the Aniline Blue dye has potential applications in nonlinear optics.     

Deep levels in gallium arsenide by capacitance methods

The three capacitance methods, i.e., TSCAP, PHCAP, and transient capacitance measurements, are applied to determine electronic properties of deep levels inn-GaAs. In the boat-grown wafer detected are the 0.30 eV electron trap withN _T =3.6×10¹⁶ cm^?3 andS _n =2.4×10^?15 cm², and the 0.75 eV electron trap withN _T =2.0×10¹⁶ cm^?3 andS _n =1.2×10^?14 cm². In the epitaxial wafer, the 0.45 eV hole trap is detected withN _T >1.5×10¹³ cm^?3 andS _p =1.4×10^?14 cm² as well as the 0.75 eV electron trap withN _T =2.4×10¹³ cm^?3.     

Interatomic force constants studies of AMF3perovskite-type crystals (A = K,Rb; M = Mg,Ni, Co,Zn, Mn)

A simple model involving only three force constants allows us to evaluate the short range interactions in perovskite fluorides from the experimental values of the elastic constants and the lattice parameters of these compounds. The results indicate that the A-F bonds are quite central in character whereas the M-F bonds are axially symmetric; thus the short range A-F interactions are assumed to have the Born-Mayer form:ZZZZZBy studying the variations of the force constants with respect to the lattice parameter r, it is determined that ρ = 0·232 , λ = 2·8 × 10^?8 ergs for K⁺-F^?; ρ = 0·232 , λ = 4·1 × 10^?8 ergs for Rb⁺-F^?; λ₂, ρ₂ and ρ₂ are respectively 6·9 × 10^?10 ergs, 0·34 , 0·98for Co²⁺-F^? and 2·9 × 10^?10 ergs, 0·46 , 1·40for Mn²⁺-F^?. Taking into account both the short range repulsive potential and the long range electrostatic potential we can study the variations of the lattice energy as a function of r near the equilibrium position and deduce a theoretical value of the lattice distance. In spite of the simplicity of the model, the discrepancy between the experimental and the theoretical values is less than 10 per cent for all the compounds.     

High resolution measurements of the line positions and strengths of the 2ν2 band of H2CO

Spectra of the 2ν₂ band of formaldehyde have been obtained with high resolution (0.035 cm^?1). Measurements were made with path lengths of 8, 16, and 24 m and at sample pressures from 0.1 to 0.3 mm Hg at room temperature (～296°K). From these data, the following constants were determined for the 2ν₂ band in wavenumber units: v₀=3471.718±0.004,A=9.3958±030013,B=1.28100±0.00024,C=1.11662±0.00024, Tbbb=-12.8±0.5×10^-6,Taabb=60±5×10^-6. The line strengths were also obtained from the data. The strengths were analyzed to determine the band strength and the rotational factors. At 296°K, the strength of the 2ν₂ band was found to be 15.5 ± 0.9 cm^?1/(cm·atm).     

Constants of quenching of 5s 22 D 5/2, 3/2 CdII levels by argon

Constants of quenching of the CdII ion Beutler levels by argon were experimentally determined. Excited cadmium ions in the 5s ^{2 2} D _{5/2, 3/2} states were produced by sputtering metal cadmium with alpha-particles at a temperature of 240°C. The quenching constants for the 5s ^{2 2} D _5/2 and 5s ^{2 2} D _3/2 CdII ion levels were found to be 1.3×10^?10 and 1.8×10^?10 cm³ s^?1, respectively.     

Effect of hydrostatic pressure on the magnetocrystalline anisotropy constant K1 of iron and nickel

Previous values of the pressure dependence of the magnetocrystalline anisotropy constant K₁ of iron and nickel were revised. These values of K₁^?1 ($\text{dK}{}_1\text{dp}$) depend on the magnetic field for iron, and do not for nickel. The value in iron extrapolated to infinitely strong magnetic field is ?7.8×10^?6 bar^?1 at room temperature and ?7.3×10^?6 bar^?1 at 77K, and in nickel at 15 KOe is ?7.5×10^?6 bar^?1 at room temperature and ?2.8×10^?6 bar^?1 at 77K.     

Time constants of radiative transitions from the 5<Emphasis Type="Italic">d</Emphasis>[3/2]<Subscript>1</Subscript> level of a xenon atom

Integral yields of spontaneous emission at wavelengths of 1.73, 2.03, and 2.65 μm have been measured upon excitation of pure xenon by a pulsed electron beam. These yields have been analyzed and experimental data have been obtained on time constants of radiative transitions 5d[3/2]₁ → 6p[5/2]₂, 5d[3/2]₁ → 6p[3/2]₁, and 5d[3/2]₁ → 6p[1/2]₀ of XeI, which appeared to be equal to (2300 ± 400) × 10^?9, (300 ± 40) × 10^?9, and (1300 ± 200) × 10^?9 s, respectively. It is shown that the experimental data are in a qualitative agreement with the results of computational and theoretical investigations. The results of averaging the experimental and calculated data are proposed for use as recommended values of the corresponding constants.     

Specific heat of NaNO2 near its transition points

Using an a.c. technique, the specific heat of NaNO₂ was measured as a function of temperature near its antiferroelectric-to-paraelectric phase transition point (T_N). The transition was found to be of the second order. The critical exponents are; α = 0·38 for ? = 2 × 10^?4 ～ 1 × 10^?1, and α′ = 0·18 for ? = ?2 × 10^?4 ～ ?3 × 10^?3. The critical exponents deduced from the scaling-law relations are roughly close to the values obtained from a random phase approximation for a system with an isotropic interaction. However, a difference was recognized between the observed exponent for the specific heat and the values theoretically given for T > T_N by the random phase approximation for a system with a short-range interaction or for a system with a long-range dipolar interaction. A thermodynamical analysis was made by using the generalized Pippard relation, and the present result was found to be consistent with the pressure dependence of the antiferroelectric transition point.     

Brillouin scattering by pure-transverse phonons in GaSe and GaS

Brillouin scattering experiments in the layer-type semiconductors GaSe and GaS by the pure-transverse phonon domains have been carried out at room temperature. Weak resonant enhancement and cancellation have been found for both materials in the region of transparency. The non-diagonal elastic constants C₁₂ have also been determined to be 3.77 × 10¹¹ dyn cm^?2 (GaSe) and 5.35 × 10¹¹ dyn cm^?2 (GaS) by measuring the sound velocities of the phonon domains.     

Analysis of the spin splitting of maxima of quantum oscillations of the resistivity of n-Bi-Sb semiconductor alloys in a magnetic field parallel to the bisector axis

In samples of semiconductor alloys n-Bi_0.93Sb_0.07 with different electron concentrations (n ₁ = 8 × 10¹⁵ cm^?3, n ₂ = 1.2 × 10¹⁷ cm^?3, and n ₃ = 1.9 × 10¹⁸ cm^?3), dependences of the electrical resistivity on magnetic fields up to 45 T parallel to the current and the bisector axis (H ‖ C ₁ ‖ j) have been measured at temperatures of 1.5, 4.5, and 10 K. The obtained dependences ρ₂₂(H) demonstrate quantum oscillations of the resistivity (Shubnikov-de Haas effect), and, in high magnetic fields, there is a resistivity maximum far away from other maxima. On assumption that this maximum is related to the spin-split Landau level N = 0^? for electrons of the main ellipsoid, the spin-splitting parameters are calculated for electrons of the main ellipsoid: γ₁ = 0.87, γ₂ = 0.8, and γ₃ = 0.73. Using these values, the oscillation maxima can be reliably related to the numbers of split Landau levels for electrons of the main and secondary ellipsoids. The dependences of the resistivity ρ₁₁ and the Hall coefficient R _31.2 on magnetic field have been measured in a transverse magnetic field at H ‖ C ₁ and j ‖ C ₂ on the sample with the electron concentration n ₄ = 1.4 × 10¹⁷ cm^?3. Using similar analysis, the spin-splitting parameter is found to be γ₄ = 0.85, which is close to the value of γ₂ = 0.8 obtained for the sample with close electron concentration (n ₂ = 1.2 × 10¹⁷ cm^?3) during the measurements in a longitudinal magnetic field. The quantum oscillation maxima of Hall coefficient R _31.2 are shifted to the range of high magnetic fields as compared to the quantum oscillation maxima of resistivity ρ₁₁.