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.     

Phonon dispersion in solid DC1 I

Phonon dispersion curves in DC1 at 109 K have been determined. Values of the zero-sound elastic constants C₁₁ = (6.29±0.23), C₁₂ = (3.95±0.22) and C₄₄ = (2.47±0.12) × 10¹⁰ dyn cm^? re obtained from fitting the data to a harmonic Born-von-Kármán model. This implies a deviation from the Cauchy relation δ = ?0.38±0.08.     

Hole contribution to the elastic constants of SnTe

Ultrasonic wave velocities have been measured in SnTe single crystals with hole concentrations of 1.0 and 4.5 × 10²⁰/cm³. The shear elastic stiffness constant C₄₄ is sensitive to the hole concentration but $\text{1}\text{2}\text{(C}{}_{11}\text{? C}{}_{12}\text{)}$ is not, a result which is consistent with the valence band pockets being sited at the L points. The non-ellipsoidal, non-parabolic multivalley band model has been used to calculate the hole contribution to the elastic constants. The calculated difference between the shear constant C₄₄ (2.78 × 10¹⁰ dyne cm^-2) for the two crystals is in agreement with that measured experimentally (2.67 × 10¹⁰ dyne cm^-2). The shear deformation potential constant E_u for the SnTe valence band is 7.8 eV at 293°K.     

Elastic constants of LaB6 at room temperature

Measurements have been made of the transit times of pulses of longitudinal and transverse ultrasonic waves propagating in single crystal LaB₆ at room temperature. A unique set of values for the three independent elastic constants has been calculated from the resultant velocities and is; C₁₁ = (45.33 ± 0.11) × 10¹¹dynecm^-2, $\text{C}{}_{12}\text{= (1.82 ± 0.17) × 10}{}^{11}\text{dyne}\text{cm}{}^2$ and C₄₄ = (9.01 ± 0.05) × 10¹¹dyne/cm². The Debye temperature of LaB₆ from these measurements is 773 K, which agrees relatively well with the X-ray Debye temperature, however, differs much from the calorimetric and electrical resistance Debye temperatures.     

Zero-field elastic constants of uvite

The theories of Kyame [1] and Koga et al. [2] on stress wave propagation in piezoelectric media are critically studied and compared with each other. Solutions of the modified Christoffel's equations predicted by each theory for piezoelectric crystals in class 3m are derived. The velocities of ultrasonic waves propagated through a gem quality uvite specimen in particular directions were measured at 293 K using the pulse-echo overlap method. All of the independent zero-field elastic moduli were calculated from the measured wave velocities and compared with the available data in the literature. The values of the elastic constants in 10¹²$\text{dyn}\text{cm}{}^2$ were found to be C₁₁ = 3.016 ± 0.2% C₆₆ = 1.028 ± 0.3% C₃₃ = 1.698 ± 0.2% C₁₃ = 0.47 ± 3% C₄₄ = 0.655 ± 0.3% c₁₄ = ?0.089 ± 6%. The calculated bulk modulus, shear modulus and Poisson's ratio, using the Voigt-Reuss-Hill (VRH) approximation, are K_H = 1.226 × 10¹²$\text{dyn}\text{cm}{}^2$, G_H = 0.826 × 10¹²$\text{dyn}\text{cm}{}^2$ and σ_H = 0.224. The Debye temperature is 764 K.     

Study of the elastic stiffness constants of thiourea by Brillouin scattering

All the elastic stiffness constants of thiourea have been measured at room temperature. The value of C₆₆(0.7 × 10¹⁰dynes/cm²) is very low. The C₁₁ and C₃₃ constants exhibit discontinuities at 169 and 202 K. The longitudinal acoustic phonons propagating in the c direction are very strongly damped in the vicinity of 202 K.     

Elastic constants of solid krypton at T = 77 K determined by inelastic neutron scattering

Long-wavelength acoustic phonons have been studied for each of the [ζ00]T, [ζ00]L, [ζζ0]L and [ζζ0]T₁ branches in solid Kr at T = 77 K by means of inelastic neutron scattering utilizing ‘cold neutrons’ as they are available in the long-wave length tail of the pile spectrum. The raw data have been corrected for resolution effects taking into account the curvature of the dispersion surface and variation of mode eigenvectors. It has turned out, that this yields appreciable shifts of the raw data. The results of our experiment give c₁₁ = 4·25 ± 0·10, c₄₄ = 2·04 ± 0·03, c₁₂ = 2·82 ± 0·12 and a value for B = (c₁₁ + 2c₁₂)/3 = 3·30 ± 0·09 × 10¹⁰ dyne/cm². Available thermodynamic data for Kr gives a derived value for B^ad = 2·58 ± 0·06 × 10¹⁰ dyne/cm² indicating a large difference between zero sound and first sound in solid Kr at high temperatures.     

Measurement of the spin-exchange and chemical ionization rate constants in collisions of polarized metastable 23 S 1 helium atoms with 32 S 1/2 sodium atoms

Experimental data on the spin-exchange rate constants for the He(2³ S ₁)-Na(3² S _1/2) system are reported for the first time. Measurements show that the spin-exchange rate constant is C _se = (23 ± 11) × 10⁻¹⁰ cm³ s⁻¹ and the chemical ionization rate constant is C _si = (29 ± 14) × 10⁻¹⁰ cm³ s⁻¹ at a temperature of 420 K. The results are compared with the data calculated from the rate constants.     

A high-resolution study of the 14.4-μm infrared band of deuterofluoroform

The FT-IR spectrum of the ν₃ parallel band of deuterofluoroform has been recorded at a resolution of 0.0045 cm^?1. Nine independent spectral parameters were determined which reproduce some 650 observed wavenumbers with a standard error of 3 × 10^?4 cm^?1. The constants derived for the ν₃ band are (in cm^?1): ν₀ = 694.2822(3); B₀ = 0.3309321(9); B₃ = 0.3302464(11); α^B = 6.859(10) × 10^?4; α^C = 1.429 × 10^?4; D₃^J = 3.168(3) × 10^?7; D₀^J = 3.188(3) × 10^?7; D_JK³ = 4.766 × 10^?7; D_JK⁰ = 4.864 × 10^?7; and D_K⁰ ? D_K³ = 2 × 10^?10.     

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.     

Brillouin scattering in ice and deuterated ice as a function of temperature

The elastic constants c₁₁, c₃₃, c₄₄ for ordinary ice and c₁₁ for D₂O ice between 12 and 250°K are deduced from light scattering Brillouin measurements for sound waves of wavevector q = 2.35 × 10⁵cm^?1. A range of temperature is found between 70 and 130°K where the elastic constants display an abnormal behaviour.     

电子极化对氟化钙离子晶体的弹性系数、压电系数和介电常数的影响

本文用黄昆的方法计算了电子极化对氟化钙离子晶体的弹性系数c₁₂-c₄₄的偏离的贡献,以及对静电与光学介电常数差的影响,其结果在数量级和方向上与实验结果符合。     

Anharmonic force constants of GaSb from the measured third order elastic constants at 300°K

The third-order elastic constants of single crystal GaSb are determined using ultrasonic pulse interferometer at 10 MHz. The constants at 300°K, in units of 10¹¹ N.m.⁻², are C_l11 = ™ 4 ·75 ± 0·06 C₁₄₄ = + 0·50 ± 0·25 C₁₁₃ = ™ 3 ·08 ± 0·02 C₁₆₆ = ™ 2·16 ± 0·13 C₁₂₃ = ™ 0 ·44 ± 0·29 C₄₅₆ = ™ 0·25 ± 0·15 These constants are used to evaluate the three anharmonic first and second neighbour force constants based on modified Keating’s model. The constants are (in units of 10¹¹ N.m⁻²)γ=− 2·406;δ=0·407;ε=−0·222.     

Adiabatic elastic moduli in ZnSe : Mn<Superscript>2+</Superscript> and ZnSe : V<Superscript>2+</Superscript> crystals

The temperature dependences of the elastic moduli C ₄₄ (C ₁₁ ? C ₁₂)/2 and C _l = (C ₁₁ + C ₁₂ + 2C ₄₄)/2 of ZnSe : V²⁺ (impurity concentration, 6 × 10¹⁸ cm^?3) and ZnSe : Mn²⁺ (9.4 × 10²⁰ cm^?3) are measured in the temperature range 1.4–100.0 K at frequencies of 52 and 156 MHz. The temperature dependences of the adiabatic elastic moduli are derived. It is established that softening of the symmetry modules is observed only in the crystal with an impurity having orbitally degenerate states.     

The analysis of symmetric rotor Raman spectra: The pure rotational spectrum of 11BF3

The pure rotational Raman spectrum of ¹¹BF₃ has been photographed. Great care was taken in the analysis to consider all the unresolved components under each observed Raman line profile. If this is ignored, systematic errors result. The final set of molecular constants obtained was B₀ = 0.34502(±3 × 10^?5)cm^?1, D_J = 4.38(±0.10) × 10^?7cm^?1, and D_JK = ?9.1(±1.0) × 10^?7cm^?1.     

The elastic behaviour of the ternary zincblende structure semiconductor CuGe2P3

A single crystal has been grown of CuGe₂P₃, a ternary semiconductor with a zincblende structure in which the copper and germanium atoms are randomly distributed on the cation sites. The second order elastic constants measured by the ultrasonic pulse echo overlap technique (C₁₁ = 13.66, C₁₂ = 6.17, C₄₄ = 6.66 and bulk modulus B = 8.67 in units of 10¹⁰Nm^?2 at 291 K) are closely similar to those of GaP and conform well to Keyes' correlation for zincblende structure crystals. The hydrostatic pressure derivatives of the second order elastic constants ($\text{?C}{}_{11}\text{?P}\text{= 4.40}$, $\text{?C}{}_{12}\text{?P}\text{= 3.9}$, $\text{?C}{}_{44}\text{?P}\text{= 0.93}$ and $\text{?B}\text{?P}\text{= 4.07}$) and the third order elastic constants (C₁₁₁ = ? 8.45, C₁₁₂ = ? 3.49, C₁₂₃ = ? 1.13, C₁₄₄ = ? 2.82, C₁₅₅ = ? 1.44 and C₄₅₆ = ? 0.69 in units of 10¹¹Nm^?2) also resemble those of GaP: even the anharmonicity of the long wavelength acoustic modes of this ternary semiconductor resembles that of its binary “parent” compound. The positive signs of the hydrostatic pressure derivatives and the negative signs of the third order elastic constants show that the acoustic modes at the long wavelength limit stiffen under pressure, an effect which is quantified here by computation of the mode Grüneisen parameters, which are all positive. The harmonic and anharmonic force constants, obtained in the valence force field model, fit well into the pattern shown by related zincblende structure compounds: the ratio ($\text{β}\text{α}$) for bond bending (β) to stretching (α) force constants is greater than 4:1; the dominating anharmonic force constant is γ: most of the anharmonicity is associated with nearest neighbour atoms. Analysis of the temperature dependence of the elastic constants on the basis of a simple anharmonic model again emphasises the similarity between the elastic behaviour of CuGe₂P₃ and GaP. The thermal expansion of CuGe₂P₃ varies almost linearly with temperature between 291 K and 1000 K, the linear coefficient of thermal expansion α being 8.21 ± 0.02 × 10^?6 °C^?1. The similar lattice parameters and elastic behaviour of CuGe₂P₃ and GaP indicate that semiconducting devices made of epitaxial deposits of CuGe₂P₃ on a GaP substrate should prove to be almost strain-free.     

Raman紫外双共振研究C2H2分子的碰撞转动弛豫

本文利用受激Raman抽运,选择性地制备了C₂H₂分子电子基态的红外非激活振动能级的单一转动态(X¹∑_g⁺,v″₂=1,J″=9,11,13),并从紫外激光诱导的A¹Au(v′₃=1)←X¹∑_g⁺(v″₂=1)荧光谱,直接测定上述三个转动态的C< 关键词：     

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).     

Elastic constants of galena down to liquid helium temperatures

The elastic constants of single crystal galena have been determined from the measured ultrasonic velocities down to liquid helium temperature. A cryostat incorporating an arrangement to inject the liquid bonding material at low temperature is described. At 5 K, the values of elastic constants are C₁₁=14.9₀, C₁₂=3.5₁ and C₄₄=2.9₂×10¹⁰ N/m².