Effect of the mutual dragging of electrons and phonons on the thermomagnetic effects in HgSe

The longitudinal and transverse Nernst-Ettingshausen (NE) effects were measured in HgSe samples doped with various concentrations of gallium, 0.6×10¹⁸<N(Ga)<4.7×10¹⁸ cm^?3. The NE measurements were performed for the classical interval of magnetic field strengths (0–40 kOe) in the temperature range from 20 to 60 K. It was established that the low-temperature NE coefficients change sign with increasing Ga concentration or the applied magnetic field strength. It is shown that all unusual features of the NE effects observed in HgSe crystals can be attributed to the effect of mutual dragging of electrons and phonons. This implies that the effect of mutual electron-phonon dragging can be experimentally detected in semiconductors with high concentration of conduction electrons.     

Quantitative laser photoacoustic detector spectroscopy: HD 5-0 transitions

Intracavity photoacoustic spectroscopy of HD in the 5-0 R(0), R(1), and R(2) transitions demonstrates the use of a transition of known strength to calibrate the response of a photoacoustic detector by simultaneous in situ measurements. Excellent agreement in line strengths for the HD 5-0 transitions is found with the earlier determination due to McKellar et al. Our experiments, however, were conducted with a pressure-pathlength product only 10^-6 of that used by McKellar et al.     

Self-broadening of principal series lines of rubidium at high number densities and oscillator strengths

The self-broadening of principal series lines of rubidium and the corresponding oscillator strengths have been measured using a steel absorption tube heated up in an electric furnace. The line profiles were obtained from absorption measurements using a grating spectrograph of high resolution in the temperature range of 340–490 °C; the number densities varied from 5 · 10¹⁶ to 8 · 10¹⁷cm^?3. The half widths deduced from the absorption profiles disagree with the classical impact approximation based on dipole-dipole interaction but approach closely the asymptotic values of the quantum-mechanical Reinsberg theory and of the “short-range”-calculations of Presnyakov. Oscillator strengths for the higher series lines were evaluated from the spectra agreeing very well with the asymptoticn ^*?3-hydrogen-like slope of the values.     

Ru原子Rydberg态的能级结构

本文描述用激光共振激发-场电离方法测量Ru原子的4d⁷(⁴F)ns系列和4d⁷(⁴F)nd系列Rydberg态的能级结构,对可能的多重态的相对谱线强度进行了计算。理论计算与实验结果符合得很好,由此可以确定出观测到的各谱线的光谱项。 关键词：     

A comparison of self broadening and shift of helium,neon and argon emission lines

Self broadening (van der Waals and resonance) and shift of Ne emission lines and van der Waals broadening and shift of He emission lines have been measured using a high pressure (0.5–3.0 atom), low current discharge. These results are compared with previous measurements in Ar and He to obtain a complete comparison of self broadening and shift of He, Ne and Ar emission lines. Oscillator strengths for the resonance transitions are obtained from the resonance broadening coefficients. The trend of the van der Waals broadening coefficients for the three noble gases is correctly predicted by a theory due to HINDMARSHet al.⁽⁴⁾ in which a Lennard-Jones potential is used in the impact theory formalism. The measured line shifts cannot be accounted for by this theory and reflect the need for more accurate quantum mechanical calculations.     

Measurement of intensities of multiplets in the 2ν3-band of methane at low temperatures

The integrated intensities of the multiplets P(1)–P(10), R(0)–R(9), and of the Q-branch in the 2ν₃-band of ¹²CH₄ have been measured at 102°K, 152°K, 202°K, 251°K, and 300°K. Comparison of our data with theoretical line strengths confirms, at all of the temperatures mentioned, the intensity anomalies observed by Margolis⁽⁵⁾ for lines in this band. The integrated intensity of the 2ν₃-band is found to be S_v = (1·76±-0·04)(300/T (°K)) cm^?2 atm^?1.     

Shock-tube measurements of the band strengths of HBO2 and OBF in the short wavelength infrared

Shock-tube measurements are described for the quantitative spectral measurement of the i.r. signatures and band strengths of molecular boron species. The boron species were effectively isolated under conditions of optimum concentration and calculated thermodynamic conditions using the shock tube technique. Spectral measurements were performed using a scanning i.r. spectrometer which was specially designed for these experiments. System calibration experiments were performed using shock heated CO and CO₂ mixtures in diluent argon, and the measured band strengths were in excellent agreement with the accepted values for these molecules. Quantitative spectral measurements were performed on the HBO₂ fundamentals at 2.7 and 5.0 μm and OBF at 5.0 μm. The corresponding band strength values measured for these band systems were 650, 1375, and 1760 cm^-2 amagat^-1, respectively.     

Improved deuterium bromide 1-0 band molecular constants from heterodyne frequency measurements

Heterodyne frequency measurements have been made on selected deuterium bromide 1-0 band transitions ranging from P(20) to R(17). Difference frequency beat notes between a tunablediode laser whose frequency was locked to the DBr absorption lines and a CO laser whose frequency was either locked or adjusted to a reference synthesized from CO₂ laser frequency standards were measured. The beat note frequency was then combined with the measured CO laser frequency to give the DBr frequency. For two of the measurements, frequency-doubled CO₂ laser radiation was substituted for the CO laser radiation. The measurements included electric quadrupole split triplets comprising the R(0) and P(1) transitions in the D⁷⁹Br isotope. New DBr constants have been determined, and a table of frequencies is presented for the calibration of spectrometers and tunable lasers in the wavenumber range 1600 to 1990 cm^?1. A table of far-infrared frequencies is also given for DBr covering the range from 50 to 206 cm^?1.     

Lebensdauern und Oszillatorstärken im Sr I- und Ca I-Spektrum

Radiative lifetimes of some highly excited levels in Sr I were measured by zero-field level crossing technique. These levels have been populated using optical excitation starting from the metastable 4d 5s ¹ D ₂ or 5s5p ³ P _2,1,0 states. The high population of these metastable levels necessary for the experiments was obtained by a discharge in the pure Sr vapour burning in the atomic beam oven. The following lifetimes have been determined (in units of 10^?8 sec):τ(5s 6s³ S ₁)=1.09±0.11,τ(5s 5d ³D₁)=1.67±0.10,τ(5s4f¹ F ₃)=3.43±0.28,τ(4d5p ¹ D ₂)=2.19±0.16,τ(5p ^{2 3}P₁)=0.88±0.12,τ(5p ^{2 3} P ₂)=0.78 _?0.10 ^+0.26 . These results are compared with lifetimes derived from oscillator strengths given in the literature, and the reliability of different oscillator strengths tables is discussed. A corresponding discussion is given for radiative lifetimes of some levels in Ca I published previously. Good agreement with data derived from arc emission oscillator strengths has been found. Ca lifetimes are fairly well consistent with oscillator strengths calculated with semiempirical scaled Thomas-Fermi-wave functions.     

Thermal diffusivity of MORB-composition rocks to 15 GPa: implications for triggering of deep seismicity

We have measured the thermal diffusivity of eclogite and majorite with a model MORB composition at pressures of 3 and 15 GPa, respectively. Both phase assemblages show inverse dependences of their thermal diffusivities on temperature: D _eclogite=9(10)×10^?10+7(1)×10^?4/T(K) m ²/s and D _majorite=6.2(5)×10^?7+3.0(5)×10^?4/T(K) m ²/s. The values for majorite are in good agreement with previous measurements for other garnets and are considerably lower than thermal diffusivities of wadsleyite and ringwoodite, which are the main components of the mantle transition zone. We discuss the implications of the low thermal conductivity of subducted oceanic crust in the transition zone for the triggering of deep seismicity.     

Exotic clustering in 232,234,236,238U

We account for the energies and electromagnetic E2 transitions of the J^π = 0⁺, 2⁺, 4⁺ … ground state bands of ^{232,234,236,238}U, using a model in which these bands are treated in terms of a ²⁴Ne cluster orbiting the appropriate Pb core. The cluster-core potential parameters used are identical to those employed in a previous study of ^222,224,226Ra. In addition to the simultaneous fitting of energies and B(E2) strengths, we also obtain good agreement with the measured half-life for the ²⁴Ne decay of the 0⁺ ground state of ²³²U and ²³⁴U as well as with the measured B(E4 ↑; 0⁺ → 4⁺) transition strengths in ^234,236U. We find that a small parity dependence of the cluster-core potential is required in order to give a good account of the energies of the J^π = 1⁻, 3⁻, 5⁻,… states of the lowest negative parity band of ^{232,234,236,238}U, and of the B(E3 ↑; 0⁺ → 3⁻) strengths in ^234,236,238U.     

Improved rovibrational constants and frequency tables for the normal laser bands of 12C16O2

New frequency difference measurements between Doppler-free stabilized laser lines in the 9.4- and 10.4-μm bands of ¹²C¹⁶O₂, including high-J and across-the-band-center measurements, have made significant improvements in the rovibrational constants. The absolute frequencies were referred to the methane stabilized 3.39-μm HeNe laser. Frequency tables generated from these constants have absolute uncertainties of less than two parts in 10¹⁰ and are about a factor of 10 better than older tables. In addition, the laser lines P_I(50) in ¹³C¹⁶O₂ and R_II(26) in ¹³C¹⁸O₂, which were used as reference lines in recent visible laser frequency measurements, were also measured to about the same accuracy.     

Beam maser measurements of hyperfine structure in chloroacetylene-d

The J = 1-0 transitions in ³⁵ClCCD were measured using a beam maser spectrometer giving a molecular resonance linewidth of 3 kHz (FWHM). Analysis of the data yielded quadrupole coupling strengths eqQ(D) = 208.5 ± 1.5, eqQ(³⁵Cl)= 79 739.5 ± 1 kHz and the ³⁵Cl spinrotation interaction strength C(Cl) 1.3 ± 0.1 kHz. The rotational constant obtained is B = 5 186 973.9 ± 1.0 kHz. The accuracy of measured molecular parameters is improved by a factor of 20 or better.     

Self-broadened widths and absolute strengths of 12CH4 lines in the 1310–1370 cm-1 region

Self-broadened widths and absolute strengths of ¹²CH₄ lines in the 1310–1370 cm^-1 spectral region have been measured at room temperature (296 K) using Fourier transform absorption spectroscopy with a 0.003 cm^-1 resolution (FWHM unapodized). The line widths, which are the most comprehensive set of measurements on self-broadened lines in the ν₄ R-branch yet reported, show a tetrahedral-symmetry dependence, which is consistent with recently reported observations. Generally, the line strengths are approximately 5% higher than those tabulated on the AFGL line-parameter compilation.     

The thermonuclear reaction rate of 58Si(p,γ)59Cu

The cross sections of ⁵⁸Ni(p, γ)⁵⁹Cu and ⁵⁸Ni(p, p'γ)⁵⁸Ni have been measured over the bombarding energy range 1.18–4.20 MeV. The measurements were based on observation of the yields of ⁵⁹Cu and ⁵⁸Ni deexcitation γ-rays and also on observation of the yield of γ-rays associated with the β⁺ decay of ⁵⁹Cu. The agreement between the two methods used for ⁵⁸Ni(p, γ)⁵⁹Cu is very good. The cross sections have been compared with the predictions of global statistical-model calculations. The calculations overestimated the ⁵⁸Ni(p, γ)⁵⁹Cu cross section by a factor ～ 2.5 and the ⁵⁸Ni(p, p'γ)⁵⁸Ni cross section by a factor ～ 1.5. The energies and (p, γ₀) resonance strengths of sixty-five resonances which feature significant resonance to ground-state transitions were measured. These energies and resonance strengths are compared with other results in the literature and good overall agreement is found. Thermonuclear reaction rates at temperatures representative of those encountered in freeze-out from nuclear statistical equilibrium in exploding stars have been calculated from the data and the results compared with those of four previous measurements reported in the literature, amongst which there is significant disagreement. The present results are in satisfactory agreement with those of the two previous measurements based on stopping-target activation measurements. The significance of the reaction rates for stellar nucleosynthesis calculations is discussed.     

Intensity measurements in the 2v3-band of 13CH4 at low temperatures

Absolute intensities of the J-multiplets P(1)-P(8), R(0)-R(7) and of the Q-branch in the 2v₃-band of ¹³CH₄ have been measured at 100, 150, 200, and 296°K. Our intensity data confirm the recent observation by Fox et al. that substitution of the isotope ¹³C for the central ¹²C atom in methane results in significantly different line strengths in the severely perturbed 2v₃-band. Our results at 296°K for the absolute intensities of R(0) and R(1) are in excellent agreement with the values measured by Fox et al.     

Total Gamow-Teller strengths from measured ground-state correlations

Recently developed sum rules for Gamow-Teller transitions as observed in (p, n) and (n, p) reactions were applied to all stable even-even target nuclei between ¹⁶O and ⁵⁸Ni and to ⁹⁰Zr. The total Gamow-Teller strengths S(p, n) and S(n, p), which depend sensitively on ground-state correlations, were calculated by the use of measured occupation numbers deduced from proton- and neutron-pickup and stripping experiments. The results are at variance with experimental observations.     

Magnetostriction constants of epitaxial La,Ga: YIG films measured by microwave resonance

The magnetostriction constants of Y_2.85La_0.15Fe_3.75Ga_1.25O₁₂ epilayers have been measured by observing the shift of the resonance line of a thin film which is stressed by three-point bending. The result is λ₁₁₁=−(0.75±0.15) × 10⁻⁶ and λ₁₀₀=−(0.4±0.1) × 10⁻⁶ which is in agreement with the measurements on bulk single crystals. This result indicates that there is no growth induced contribution to the magnetostriction in thin films of this garnet grown by liquid phase epitaxy.     

Absolute Line Intensities in the 2ν3Band of16O12C32S

The strengths of 100 lines in the 2ν₃band of¹⁶O¹²C³²S have been measured at high resolution in the spectral range 4069–4118 cm⁻¹, using a tunable difference-frequency laser spectrometer. These intensities were obtained by fitting Voigt profiles to the measured shapes of the lines. The vibrational transition moment [(2.141 ± 0.020) × 10⁻²D] and the absolute intensity (16.19 ± 0.24 cm⁻²atm⁻¹at 296 K) of the 2ν₃band of¹⁶O¹²C³²S are determined from these linestrength measurements.     

Compositionally asymmetrical multiquantum wells: “Pseudo-molecules” for giant optical nonlinearities in the infrared (9–11 μm)

Intersubband transitions in quantum well have extremely large oscillator strengths and induce strong nonlinear effects in structures where inversion symmetry is broken, realized by growing AlGaAs quantum wells with asymmetrical A1 gradients. These compositionally asymmetrical multiquantum wells may thus be viewed as giant “quasimolecules” optimized for optimal nonlinearities in the mid infrared. Optical rectification as well as second harmonic generation have been measured in those structures using a continuous CO₂ laser. At 10.6 μm the nonlinear coefficients are more than 3 orders of magnitude higher in these samples than for bulk GaAs (i.e. χ₀⁽²⁾ = 5.3 × 10⁻⁶m/V, χ_2ω⁽²⁾ = 7.2 × 10⁻⁷ m/V) and are in good agreement with theoretical predictions. We present more complex “pseudo-molecules” involving weakly coupled quantum wells. The optical rectification effects in these devices are so large χ₀⁽²⁾ = 1.6 × 10⁻³ m/V) that application to infrared detection may be envisioned.