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By condensation of metals from the vapour onto a cooled substrate an especially high degree of disorder can be frozen in. Such strongly disordered films show essential changes of their properties. This paper deals with optical studies of such films of Bi, Ga, Sn and Ag. Reflectivity and transmission and their changes during annealing are measured in the spectral range from 0,25 to 4 microns. There is reasonable agreement with results of other measurements e.g. Hall-voltage, electrical resistance and electron diffraction. Optical constants and their changes during annealing are calculated in the range from 0,8 to 4 microns by approximation formulas. The high disorder produces similar anomalies of the optical constants as observed so far at extremely thin films. Concentrations and collision frequencies of free electrons are determined by means of the Drude theory. These values, obtained by a purely optical method are compared to results of electrical measurements and show satisfactory agreement. [ABSTRACT FROM AUTHOR]

This paper describes the measurement of ionization and charge exchange cross-sections for hydrogen atoms (H), Protons (H) and molecular hydrogen ions H and H in hydrogen gas in the energy range 9 to 60 keV. Further, the emission of secondary electrons from copper-beryllium by impact of these particles was measured. A beam of monoenergetic neutral hydrogen atoms was produced by charge exchange of a beam of protons in a gas chamber. Separation of the charged and uncharged components was accomplished by a magnetic field. The pressure in the chamber in which the cross-sections were measured was so low, that only a few particles of the incident beam suffered an effective collision. The positive and negative charges, which were produced by ionization and charge exchange along the path of the beam, were extracted by a transverse electric field and the saturation current was measured. The intensity of the neutral beam was determined at the same time by repeated charge exchange in an 80 mμ thick foil of aluminiumoxide. [ABSTRACT FROM AUTHOR]

A strong-coupling approximation method for the Chew-Low meson-nucleon scattering formalism is developed, considering, for simplicity, the case of charged scalar mesons. As a starting point, the Low equation formulated for the case of strong coupling is stated. This formulation explicitly takes into account the formation of excited compound-nucleon states which arise in the case of strong coupling. The data concerning the zero-meson part and the compound-nucleon excitation energies, necessary to specify this Low equation, are introduced approcimatly by means of the field-splitting transformation developed in a previous paper. The one-meson approximation is constructed; this corresponds to a certain kind of many-meson approximation of the usual Low equation whose limit as g→∞ holds exactly. It is hoped that these considerations will serve to guide an analogous investigation using the pseudoscalar theory. [ABSTRACT FROM AUTHOR]

The paper investigates the possibility of obtaining improved eigenfunctions of the reduced Bardeen-Cooper-Schrieffer-Hamiltonian by forming linear combinations of the approximative BCS-functions. For the groundstate an admixture of states with two excited pairs is considered. This leads to a lowering of the ground-state by an amount δW which is independent of the volume and of the same order of magnitude as the energy-gap 2 ɛ. The same shift is produced for the states with excited single-pairs. Superposition of states with one excited pair leads to an additional discrete level within the energy-gap. [ABSTRACT FROM AUTHOR]

Papers from Ekertowa and Dember show contradicting results concerning the additivity of photoelectric current and secondary electron current. We found, upon investigation, that additivity exists between photoelectric current and secondary electron current for metals in agreement with Ekertowa. The large departures from additivity, observed by Dember, receive reasonable interpretation in terms of an internal photoelectric effect in the oxide layer of his target. [ABSTRACT FROM AUTHOR]

The paper gives a simplified treatment of the thermodynamics of the Bardeen-Cooper-Schrieffer-theory. It is shown, that all functions can be represented with the help of a function a ( x) and its derivatives. Newly calculated tables of thermo-dynamical functions are given. [ABSTRACT FROM AUTHOR]

It is shown in this paper, that it is possible to construct parity conserving baryonpion interactions which are γ-invariant in exactly the same manner as electromagnetic and weak interactions. [ABSTRACT FROM AUTHOR]

In a previous letter a generalized γ-invariance for strong interactions has been proposed and some consequences of this invariance have been outlined. The present paper contains the detailed proof and discussion of these consequences. For the baryon-pion interactions one obtains two possible forms for the coupling: The K-meson couplings themselves should violate the invariance against space reflections. [ABSTRACT FROM AUTHOR]

Copyright of Zeitschrift für Physik is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper a model theory is demonstrated by which it is possible to determine the load capacity of a wall including an electric arc. This theory bases on exact numerical computations of the temperature distribution inside the wall of a toroidal arc tube. It is shown and explained that the thermal load capacity increases with the radius of curvature at fixed tube radius and decreases with the tube radius at fixed radius of curvature. [ABSTRACT FROM AUTHOR]

The isochromats of the elements C, Si and Ge have been measured. The targets were used in the monocrystalline as well as in the polycrystalline modification. As in the case of Al, which has been treated in the preceding paper, the isochromats are successfully discussed in terms of the 'nondirect transition' process. This result points out the possibility of obtaining information about the initial level of some direct interband transitions by isochromat measurements. The discussed experimental results agree well with corresponding calculations. In the case of Ge the results show, that the energetically lower maximum in the ɛ(ω)-curve corresponds to the transition L′→ L rather than to the transition Λ→Λ. [ABSTRACT FROM AUTHOR]

In this paper the analysis of gas heating phenomena in wallstabilized toroidal electric arcs is derived and the results are applied to a nitrogen arc at a pressure of one atmosphere. These investigations have been performed on the basis of the single-fluid model of plasma physics taking into consideration the thermal properties of the wall material. By using a differential method it is outlined how the equation of energy is solved not only in the arc but also in the wall. [ABSTRACT FROM AUTHOR]

A pair of surfaces has been produced by cleavage of a semiconductor crystal, containing the same concentration of donors just below the freshly exposed faces. Two types of experiments have been carried out: The differential capacity C of these contacts was measured as a function of bias voltage U. In spite of the equality in donor concentration for the pair of contacts the slope of the plots 1/ C( U) differed in both types of experiments. This result cannot be explained by Schottky's theory. A paper proposing a model for interpretation of the results is in preparation. [ABSTRACT FROM AUTHOR]

A spherical Fabry-Perot spectrometer with an absorbing atomic beam passing the interior of the interferometer is described. By use of the internal beam it is possible to reduce the amount of material needed for the atomic beam source to a few milligrams per hour. The set-up is especially suitable for hyperfine structure and isotope shift investigations. For the photoelectric recording of the signal the geometrical distance between the spherical mirrors was changed using the piezoelectric effect. In order to reduce the influence of the intensity distribution of the light source I(λ) the ratio [ I(λ)- I(λ)]/ I(λ) was measured, where I(λ)= I(λ) exp (- V· k(λ)· d) is the observed intensity with absorbing atoms between the mirrors, and V the increase of the absorption signal due to the multiple reflections of the light through the atomic beam ( V≈75). For an accurate and easy evaluation of the data this ratio was measured by a digital voltmeter and punched into paper tape. The small line width of the absorption profile obtained in the experiments with Tm and Eu enabled us to measure hyperfine distances of the order of 5 · 10 cm to 20 · 10 cm with an error not exceeding 0.1 · 10 cm in some cases. From the measurements the A-factors for five levels of the configurations 4 f6 s 6 p and 4 f5 d 6 s in Tm I and the A- and B-factors of the stable Eu isotopes of the 4 f 6 s 6 p y Plevel in Eu I were determined. [ABSTRACT FROM AUTHOR]

The superficial processes produced by the fast electrons in a d.c. glow discharge may influence the values of the potential difference measured with the Hall probes. In order to obtain a good agreement between calculated and measured Hall voltages it is necessary to exclude these superficial processes, specially the secondary electron emission, at the surface of the Hall probes. In this paper the mentioned influence and the optimum work conditions for Hall probes measurements in a d.c. glow discharge are studied. [ABSTRACT FROM AUTHOR]

A previous paper by Drees and Paul reported measurements on a plasma betatron. The study was continued using a betatron field with a vector potential taking into account the self magnetic field of a plasma current. The plasma was produced by a high frequency electric quadrupole field without an azimuthal magnetic field. The bremsstrahlung intensity of the accelerated electrons was observed as a function of gas pressure and accelerating field. The maximum energy of the electrons was 1.3 MeV compared to 1.5 MeV given by the field parameters. The maximum number in this energy range was about 10 per pulse corresponding to a circulating runaway current of ∼ 1 A. The conduction current was drasticly reduced by coating the inner wall of the quartz glass torus with a thin layer of graphite. This change in the plasma current did not influence the γ radiation intensity. [ABSTRACT FROM AUTHOR]

In Ref. a method was described by use of secondary ion emission to generate wellcollimated and intense beams of heavy negative ions. In this paper the processes are studied that govern the emission of molecular ions from continuously regenerated surfaces. A rotating iron target was bombarded by noble gas ions in the energy range from 17 to 30 keV. The secondary ion yield was measured as a function of primary current density, mass and energy of the primary ions, gas pressure and the rotation frequency of the target. [ABSTRACT FROM AUTHOR]

The motion of a rigid rotator in an electrical field is well known for small fieldstrengths where it is identical with the second-order perturbation of the Stark effect. At large fieldstrengths, the rotator becomes almost fixed about the field direction and its levels coincide with those of an harmonic oscillator. In this paper the energy levels are calculated by diagonalization for the intermediate region and its deviation from the two limiting cases is briefly discussed. [ABSTRACT FROM AUTHOR]

In a previous paper we proved that the usual expressions for energy- and particle-density are indefinite even in the one-particle subspace. Therefore we pursue an axiomatic approach in constructing definite quantities and arrive at a nonlocal theory. [ABSTRACT FROM AUTHOR]

In this paper the time resolved spectrum of a Rhodamin-B-dye-laser is investigated. Besides the already wellknown features a second line has been observed in the case of higher pumping power lasting several us. The emission of the second laser line begins when the first line decays and lasts about as long as the pumping puls. The wavelength is about 100 Å shorter than that of the first line. A laser transition in the triplett system of the dye molecule is assumed. [ABSTRACT FROM AUTHOR]

In this paper properties and dependence upon parameters of electric d.c. arcs with a.c. components are investigated. Expanding older theories analytical solutions of the basic equations of the one fluid modell are given for this problem using an extended Bessel modell and numerical calculations are made. Thereby the exact equations determine dependences upon parameters in limiting cases. The obtained results are compared with experimental data given in literature. The good agreement shows the validity of the applied methods. [ABSTRACT FROM AUTHOR]

The present paper starts form the original Ginzburg-Landau-equations of superconductivity and the linear theory of elasticity for internal stresses as well as the experimental fact that the specific volume and the elastic constants vary throughout the superconducting phase. With the aid of phenomenological expressions for the free energy and the spontaneous deformation (superconductive magnetostriction) of a deformable type II superconductor, a general method is given for the determination of the interaction between the field of the order parameter, the magnetic field, and the field of the elastic deformations. For an isolated straight vortex-line and for a straight vortex-line in the neighbourhood of a dislocation of arbitrary character, formulas for the internal stresses are derived using first order perturbation theory (corresponding to first powers in the changes of specific volume and elastic constants). [ABSTRACT FROM AUTHOR]

To generate transverse microwave phonons in nonpiezoelectric crystals one has to use ferromagnetic filmtransducers. This method needs a static magnetic field of some kOe. It is shown in this paper that it is possible to shift the resonance field to lower values by applying mechanical stress to the ferromagnetic film. Due to the broad linewidth even at zero field transverse phonons are generated. The measured conversion factor for generation and detection is −50 dB each which is comparable with values by other methods. The conversion factor depends strongly on the conditions during evaporation of the film. [ABSTRACT FROM AUTHOR]

Investigations on ion lasers with large bored tubes (7 ... 15 mm I.D.) without additional axial magnetic field are performed. An axial magnetic field is shown to be not necessary to achieve high laser power. By absence of additional magnetic fields the laser construction is considerably simplified. Experimental criterions for maximum laser power are derived by means of a previously published theoretical paper. 120 W total power summed up over the 4 p-4 s Argon II transitions in the visible part of the spectrum, and 1.5 W ultraviolet power in Argon (3638 Å, 3511 Å) and Krypton (3507 Å) are obtained in continuous mode operation. High inversion densities of 7 · 10 cm give rise to non-resonant laser oscillations. By multipass amplification the spontaneous emission is amplified up to 20 W/cm, having a beam divergence of about 10 rad. All results are pointing out the influence of radiation trapping effects on the laser power to be smaller than estimated and measured by other authors using conditions deviating from our optimum conditions for maximum laser power. [ABSTRACT FROM AUTHOR]

By the sudden change of nuclear charge during β-decay the daughter-ion is ionized or excited with probabilities of the order of some percent; other processes in the electron shell may be neglected, therefore unperturbed excitations can be measured by detecting photons emitted from the decaying excited atomic states in delayed coincidence with β-particles as is shown in an earlier paper for the Kr 85-β-decay. More extensive measurements of the photonemission after this decay give results in good agreement with theoretical predictions. Mostly such photons are observed, which can be emitted after a monopol-excitation, for which the selectionrules Δ J=0 and Δ l=0 are valid. The total excitationprobability into both 5p(J=0)-states of Rb II is found to be P(4p−5p)=5,6±1,0%. The lifetimes of these two states are measured (correspondingly) to be τ=7,6 ±0,5 nsec, from which the reduced matrixelements ¦〈5p∥D∥5s〉¦=18,9±3,2 and ¦〈5p∥D∥4d〉¦=10,4 ±1,8 a.u. are calculated. [ABSTRACT FROM AUTHOR]

In this paper measured probability distributions of the electron ejection from solids due to bombardment by atomic particles with kinetic energy are compared with theoretical distributions. With regard to the applied measuring parameters, it is shown that best adaption is obtainable by use of one of the suggested theoretical distributions respectively. A heuristic foundation is given for this fact, and the assumption is confirmed that careful measurements of the probability distributions are additional sources of information with regard to the investigation of the atomic particle-induced electron ejection. [ABSTRACT FROM AUTHOR]

In liquid helium two wave modes are possible. Their properties may be analysed by solving the thermohydrodynamical equations under the condition that the tangential component of the normal fluid velocity is vanishing on the walls. In the present paper, these two types of wave propagation are determined for a plane-parallel capillary with the heat conduction and the thermal expansion being neglected and with the width of the capillary being much smaller than the penetration depth of a viscous wave. In particular, the dispersion relations of both, the so called fourth sound and an overdamped mode are calculated. (This overdamped mode may be called fifth wave mode.) The velocity fields can be determined, too, as well as the pressure fields and the temperature fields. It is shown, that pressure and temperature are coupled in both cases. [ABSTRACT FROM AUTHOR]

In this paper a theory of electromagnetic surface-waves on a semiinfinite metal is given, which takes the complete Maxwellian equations into consideration. The dispersion relation between the frequency and the wave-vector along the surface is derived and the relations of the components of the electromagnetic field as functions of the frequency are analysed. The excitation of the surface waves by the idealised mechanism of an dipole oscillating normally to the surface is shown. The case of a dipole oscillating parallelly to the surface is investigated too. [ABSTRACT FROM AUTHOR]

It is shown that the classification of curved space-times into Machian and antiMachian world models proposed by Hönl and Dehnen is inadequate. We prove that even the static Einstein model would be anti-Machian according to the definition of these authors, in contrast to their assertion. The proof is based on the theorem, established in this paper, that any Robertson-Walker space-time admits regular source-free Maxwell fields. [ABSTRACT FROM AUTHOR]

This paper realizes an idea of Redfield in a general and quantitative manner: Charged point defects produce local electric fields in a crystal which cause a change in the absorption-constant compared with the absorption-constant of an undisturbed crystal (Franz-Keldysh-effect). Thus one gets a tail in the absorption constant decreasing from the ideal intrinsic absorption edge towards longer wave-lengths. Applying an external field F one finds an additional, frequency-dependent absorptionconstant Δα. Its magnitude and spectral distribution depend on the concentration of defects. For external fields smaller than the internal ones Δα∝ F holds at all frequencies. The results are compared with those found by Franz. [ABSTRACT FROM AUTHOR]

UV-irradiation at low temperatures may bring hydrogen atoms into interstitial sites (produce U centers) in alkali halides. At about 100 °K the hydrogen atoms begin to leave their sites and may react with any diamagnetic center X to a paramagnetic center HX. In this paper CN and NCO ions are used for X. The paramagnetic centers are investigated by the method of ESR. The spectra and thermal properties ofHCN,HCN,HCN,HNCO andHNCO are described. As well signals are found, which may be attributed to theHCN center. A simple cryostat is described for use at temperatures continously variable between 25 °K and 500 °K. [ABSTRACT FROM AUTHOR]

An expression for a charge density of the Klein-Gordon field is constructed which is the 0-component of a four-vector as well as positive-definite if one confines oneself to positive frequency solutions only. The latter is not the case for the usual density as was shown in a preceding paper. [ABSTRACT FROM AUTHOR]

The wellknown derivation of Fresnel's formula for the reflection coefficient of a metal surface in the case of an oblique incident wave polarized parallel to the plane of incidence includes a mistake concerning the boundary conditions and neglecting the possibility of optical excitation of plasma waves. The right formula for this case is derived in the following paper by Forstmann. The discussion of an approximate formula obtained by a simplified method leads in the case of vanishing reflectivity for Ω>Ω to a real Brewster-angle α. For Ω<Ω there exists another solution with a complex Brewster-angle, representing a surface wave in form of a Zenneck-wave. For large wave numbers and for light velocity ≫ electron velocity the dispersion formula for these surface waves is nearly identical with that obtained by Ritchie and Wagner, while for small wave numbers there is a great difference between these two formulas. In the middle region the frequence Ω is nearly Ω/√2. [ABSTRACT FROM AUTHOR]

To study saddle point states of fissioning nuclei in the single-particle model nucleon wave functions and energy-levels for highly deformed nuclei are needed. In this paper a method is developped to calculate single-particle wave functions and energy eigenvalues for potentials with any axially symmetric deformation. For that purpose the eigenvalue problem for the partial diefferential operator H is replaced by a discrete approximation. A special method is worked out to solve the resulting algebraic eigenvalue problem. [ABSTRACT FROM AUTHOR]

A theoretical treatment of the optical behaviour of thin metallic films with island structure was given in part (I) using a generalized Maxwell-Garnett formula. In this paper a more complete description is presented taking into account the dependence of the optical constants on particle size. Experimental data for particles below 20 Å can be fairly well expressed by calculated curves. The theory predicts, however, too sharp maxima in the spectral distribution of the absorption for larger particles. In order to achieve better agreement the area under the 'bell' shaped absorption curves is used which is rather independent of the size and conductivity of the particles. The areas obtained compare well with experimental data. Thus it is possible by superposition of adjacent theoretical curves (belonging to different sites of the maxima) to take into account the inhomogenity of the experimental films and to get the correct magnitude of the maximum. The change in area with the position of the maximum is mainly caused by interband transitions which contribute to the dielectric constant also outside of the interband absorption range. It is improbable, however, that inhomogenity is the only reason for broadening. It is suggested that coupling between the microcircuits will also be important. An attempt is made to get information on the temperature dependence of the effective mass by analysing the temperature dependence of the optical absorption. [ABSTRACT FROM AUTHOR]

The velocity dependence of the total scattering cross section has been measured for 10 different combinations of alkali atoms with rare gas atoms. By means of an automated fast comparison technique the precision of relative values of Q(ν) can be increased to 10. In the eight cases where Ar, Kr or Xe is the scattering gas, undulations of Q(ν) about its mean value have been observed. The precision of the method allows us in these cases to extract reliable information on the amplitude of the undulations. Use of this additional information makes it impossible to explain the experimental results with the simple, 2- or 3-parameter potentials that are generally used. Deferring a final evaluation to a later paper, we restrict ourselves here to giving, for the Lennard-Jones (8−6) potential, a table of ɛr values. [ABSTRACT FROM AUTHOR]

In recent papers we have reformulated the quantum theory of fermions in a lattice space with a finite number of points, say Z. Of course, Lorentz invariance holds only in the limit Z→∞. So far a lattice space with Z points provides us only with a convenient method to define the order of some limiting processes. - Here we discuss a more fundamental question. According to general relativity Lorentz invariance can not hold all over the world and must also be broken at tiny distances of the centers of particles. If the space curvature is not essential for the theory of elementary particles, as generally is assumed, we must only take into account the topological structure of the deviations from Lorentz invariance. In this respect the lattice space provides us with a rather rough but sufficient picture of a space, being approximately Lorentz invariant only for intermediate distances. - In a lattice with Z points the Hilbert space has a finite number of dimensions. It seems to us important that this assumption will hold, even if we proceed to a more refined space model. [ABSTRACT FROM AUTHOR]

In previous papers we have developed the Dirac equation in a lattice space with a finite number Z of points. This equation is quasi relativistic. For in the limit Z→∞ we obtain the relativistic energy-momentum relation. Here we derive the quasi relativistic interaction operator from a lattice space. First we prove that, without any loss of generality, the number of particles can be assumed as constant. Then we deduce an interaction operator being uniquely defined by some postulates, the most important of which are (i) the particle-hole symmetry (either the particles or the antiparticles may be considered as holes), (ii) the Racah covariance (eigenvalues are symmetrical to zero), (iii) the Touschek covariance (eigenvalues depend only on the square of the bare mass κ). The other postulates are more or less obvious: 2-particle-forces, local interaction, translation invariance and cube symmetry. In the limit Z→∞ the operator is Lorentz invariant. Since the parity symmetry is broken, some alternative systems of postulates are considered. Finally we point out that the proper elementary particles are quasi particles in a certain Dirac sea of a constant number of urfermions. Essentially as in Dirac's original theory of free particles the urfermions occupy half of the quantum places of the lattice. Of course, the Dirac sea now is modified by interaction. [ABSTRACT FROM AUTHOR]

A Complete orthogonal system derived in an earlier paper is used to analyze the Dalitzdiagram for the three α-particles in the decay of carbon 12. The hypothesis, that only few of these orthogonal functions will be of importance, is confirmed. [ABSTRACT FROM AUTHOR]

M centers in alkali halides consist of two F centers combined along one of the 〈110〉 directions of the crystal. In addition to the singlet ground state a metastable triplet state has been observed. The paper deals with the absorption and excitation spectra, the kinetics of the production and the spontaneous and the induced decay of triplet M centers in KCl. [ABSTRACT FROM AUTHOR]

For various cathode metals Kesaev has measured the arc lifetime as a function of current. Recently Kingdon, assuming the field emission theory could not explain these experiments, suggested that the secondary electron emission produced by positive ions through a diffusion-controlled neutralization process determines the cathode mechanism. In this paper another assumption is made, based on the field emission theory: the cathode needs a minimal energy-supply for evaporation in order to maintain a higher vapourpressure and ion density near the cathode. For the mercury cathode this assumption seems to be valid. The temperature of the cathode spot and the voltage drop in front of it, for Bi, Pb, Zn, Tl, Cd, In, Sn, Cu, is not yet exactly known. Therefore the validity of the assumption made, concerning these materials can only be proved qualitatively. [ABSTRACT FROM AUTHOR]

The equations of motion for a radiating charged point particle, derived in a preceding paper, are solved for some simple examples (no external forces, harmonic oscillator). We obtain solutions with reasonable behavior having no run-away solutions, as in other theories. We also compare our equations with some equations proposed by other authors. [ABSTRACT FROM AUTHOR]

Completing a former paper about scattering experiments with electrons a new foil containing an element of high atomic number (lead) has been produced, which shows a very equal and fine distribution of lead. [ABSTRACT FROM AUTHOR]

In the electric field as has been shown theoretically by Franz and Keldysh there is in crystals an absorption edge shift towards longer wave-lenghts. This effect has been studied and verified on CdS by Böer and co-workers and has led to a more profound understanding of many problems of CdS single crystals conductivity. This paper is a first report on the absorption edge shift of ZnS single crystals in the electric field. [ABSTRACT FROM AUTHOR]

Copyright of Zeitschrift für Physik is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The application of high gain image intensifier and image converter streak shutter techniques to investigations of faintly luminous early stages of gaseous discharges discloses in some detail the development of electron avalanches into anode- and cathode-directed streamers as soon as the critical amplification ( n≈10) is attained in the gap. The velocities of both of the streamer branches were measured quantitatively as to the dependence on pressure ( p), field ( E/p) and gas (Nitrogen and various mixtures), typical values being 0.5 ... 1 · 10 cm/sec. We find that streamer propagation is suitably described in a coordinate-system drifting with the electrons (driftvelocity v ≈ 1 · 10 cm/sec) and that the way it depends on the discharge parameters suggests that ionization by electron impact (in the eigen-spacecharge distorted field) and photoionization are the determining effects. - The cathode-directed streamers show a considerable intensification and acceleration as soon as they are encountered by cathodic secondary avalanches, which however are obviously not essential for the initiation of the process in itself. - The streak images give also an impression of persisting excitation and ionization processes in the region of the streamer-paths and of the transition into the beginning of the bright spark, correlated with several ionizing fronts observed moving towards anode or cathode with velocities even >10 cm/sec. (The paper includes also details of the gaseous near UV-radiation which was utilized for registration with image intensifier or converter, especially with respect to the decaytime of the excited states.) The results obtained are essentially a verification and to some extend completion of predictions made on the basis of early cloud chamber investigations. [ABSTRACT FROM AUTHOR]

The superconducting transition of thin films of Al, In, Tl, Pb, Sn, and Ga is investigated by resistance measurements before and after the low temperature oxidation of the surface. The films are condensed onto a crystalline quartz plate to a thickness of about 100 Å or less at a temperature of mostly 105 °K. The oxidation process below 40 °K was described in a previous paper. After a theory of Mott, it may be understood by the tunneling of electrons from the metal to some acceptor levels of the oxygen molecules at the outside of the oxide layer. This way, a strong electric field arises which, on the one hand, facilitates the motion of metal ions outwards to form oxide molecules and, on the other hand, is suspected to affect the transition temperature. The experimental results show a shift of the transition to higher temperatures with the metals Al, In, and Tl, however, with the metals Sn, Pb, and Ga to lower temperatures. These results agree qualitatively very well with direct measurements of the influence of surface charges on the superconducting transition of Sn and In by Glover and Sherrill. The T-shift depends clearly upon the film thickness and amounts to about 0.3 to 0.4 °K for the thinnest films used. Some experiments are undertaken in order to prove the existence of the electric field. Removing the residual oxygen molecules on top of the oxide layer destroys the acceptor levels and causes a reduction of the transition temperature to the value observed with the oxygen free film. As expected, the thickness of the oxide layer is not important for the magnitude of the T shift. [ABSTRACT FROM AUTHOR]

The semiconductor laser is treated by a simple model which assumes parabolic bands. The optical transitions are supposed to obbey the usual k-selection rule. The position of the first running laser mode is considered both as a function of the degree of inversion and of temperature. The treatment includes also the effects of the response of the electrons to the lightfield (hole burning) as derived generally in a preceding paper. [ABSTRACT FROM AUTHOR]

From the exciton spectrum of the alkali halides it can be shown that the P-function of the alkali atom seems to be necessary, if one wants to construct certain excitons by means of atomic orbital functions. A relation between the ionisation energy of the exciton and the optical dielectric constant has been obtained from the experiments. This is consistent with a hydrogenic model of the exciton, which we have used in an earlier paper. [ABSTRACT FROM AUTHOR]

Copyright of Zeitschrift für Physik is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)