摘要:

The published experimental data for the far‐infrared SO2molecular laser is correlated with the results of some new experiments. A satisfactory assignment of all of the lasing lines is presented. An excitation mechanism involving excitation to the first excited singlet electronic state, followed by crossing to the highly vibrationally excited levels of the ground electronic state, and then by selective vibrational relaxation, is shown to be consistent with the experimental data.

ISSN:0021-8979    

DOI:10.1063/1.1662262

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A theory is given for (i) the linear Stark effect of the substates of the first excited level of the hydrogen atom and (ii) the linear Stark broadening of the Lyman &agr; line, in a three‐dimensional stochastic electric field. The latter is represented in the form of a three‐dimensional Fourier series with different random amplitudes and random phases for each vector component of the wave modes, which simulates a perturbing vector field varying with respect to intensity and direction in a random manner during an atomic transition. The line‐shape function, which is a moment of the distribution function of the random amplitudes and random phases of the stochastic field, is evaluated by statistical methods. It is shown that the Lyman &agr; line consists of a sequence of discrete spectra (Fourier analysis) at the frequencies &ohgr;=n&ohgr;p,n=0,±1,±2, etc., where &ohgr;pis the plasma frequency. The line intensity decreases exponentially with the square of the order numbern. The half‐width of the spectral line is proportional to the square root of the mean square stochastic electric field. In the case of electron acoustic turbulence, the half‐width is related to the unperturbed electron pressure. These results permit a quantitative determination of the intensity of the stochastic electric field and the average electron pressure in turbulent plasmas.

ISSN:0021-8979    

DOI:10.1063/1.1662263

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Transient photocurrents associated with optical depopulation of electron trapping centers have been studied as a function of photon energy in thin amorphous silical films grown on silicon wafers. A summary is given of the application of this technique to determine inhomogeneous trap state distributions in silica films. Electron trapping distributions observed at 1.9 eV and 2.5 eV below the conduction band edge of the silica and having densities of 1014/cm3are reported. Measurements at liquid‐nitrogen temperature indicate the presence of shallow trapping states of similar concentration levels in addition to the deep trap distributions.

ISSN:0021-8979    

DOI:10.1063/1.1662264

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Experimental values are given for the yields and spectral energy purities ofKx‐ray beams emitted at 120° and 180° from various targets when bombared by 0.01‐ to 3.0‐MeV electron beams. Yields and purities are determined for beryllium, carbon, aluminum, titanium, copper, silver, and gold targets as a function of the target thickness and target inclination angle.

ISSN:0021-8979    

DOI:10.1063/1.1662265

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The electron diffusion length inp‐type GaAs:Ge grown by liquid‐phase epitaxy has been measured as a function of hole concentration. The direct measurements were made by two different techniques —a laser beam scan on beveled samples and an &agr; particle scan on cleaved samples. These measurements are in good agreement and show that the diffusion length increases from ∼6 &mgr;m atp=1×1019cm−3to ∼20 &mgr;m atp=7×1016cm−3. In addition, the diffusion length was estimated from electroluminescent decay times ofp‐njunctions and the values obtained were in reasonable agreement with those directly measured for the same materials.

ISSN:0021-8979    

DOI:10.1063/1.1662266

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Change of the junction capacitance under the illumination of monochromatic radiation has been observed in GaPn+pjunctions. The peaks were observed at 1.8 and 2.4 eV at 77°K. The 1.8 eV peak was attributed to the hole activation from Fe3+to the valence band. The photoconductivity spectrum and the transient phenomenon of the photoconductivity inp+njunctions and in high‐resistivityn‐type bulk crystals also showed the presence of the 1.8 eV level due to Fe.

ISSN:0021-8979    

DOI:10.1063/1.1662267

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The real and imaginary parts of the complex index of refraction in theR‐line region of ruby have been measured near liquid‐nitrogen temperature with sufficient resolution that theR‐line doublet structure was well resolved. A modification of the usual Babinet compensator technique was used for the refractive‐index measurements, which were found to correlate with the absorption measurements as predicted by the Kramers‐Kronig relations. An attempt at direct quantitative verification of the dispersion relations for an optically pumped sample is also described.

ISSN:0021-8979    

DOI:10.1063/1.1662268

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Two acceptor levels at 0.06 and 0.12–0.14 eV were observed in nominally pure ZnTe crystals using electrical transport measurements. Results on as‐grown and annealed crystal show that these two levels are associated with different defect centers. It is suggested that neither level represents the first or second state of ionization of the native defect which dominates the electrical properties of pure ZnTe crystals at high temperatures. The deeper level appears to be associated with an impurity, possibly Cu. The identity of the shallow‐level center is unknown; however, this center may be a complex center involving the native defect. Analysis of the temperature dependence of the hole mobility confirms that optical phonon scattering is dominant near room temperature in nominally pure ZnTe; however, ionized impurity scattering may become dominant at low temperatures.

ISSN:0021-8979    

DOI:10.1063/1.1662269

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The rf impedance of a superconducting weak link with negligible capacitance is calculated for a variety of operating conditions. It is shown that the impedance is always real between harmonic steps of theI‐Vcharacteristic. The real part of the impedance is negative under certain conditions of bias for small rf signals, thus indicating the region of self‐oscillation of the weak link.

ISSN:0021-8979    

DOI:10.1063/1.1662270

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Numerical solutions have been obtained for the magnetic field produced by eddy currents induced in a hollow superconducting cylinder by a centered coaxial solenoid. As the dimensions of the cylinder and the solenoid are arbitrary, the solutions are useful in the design of many types of cryogenic apparatus. The results of studies of the performance of superconducting shields as a function of the length‐to‐diameter ratio, of the effectiveness of a shield in containing the field of an interior solenoid, and of the use of a superconducting cylinder to homogenize the field produced by a solenoid are discussed. The conclusions apply to all thin‐walled conducting cylinders as long as the wall thickness is greater than the skin depth at the frequency of interest.

ISSN:0021-8979    

DOI:10.1063/1.1662271

出版商:AIP    

年代:1973

数据来源: AIP