摘要:

AbstractIn part I of this paper the SLATER‐sums of two charged particles were expanded in TAYLOR‐series with respect to the distance between the particles. Using these expansions we calculate the binary SLATER‐sums for small values ofr(r≪ λ) λ‐thermal wavelength). In the case ofr≫ λ the binary SLATER‐sums can be approximated by the classical BOLTZMANN‐factor. In the intermediate regionr≈︁ λ we get the binary SLATER‐sums by interpolation. For high temperatures we obtain KELBG's result. For special cases the binary SLATER‐sums and the binary distribution functions are presente

ISSN:0003-3804    

DOI:10.1002/andp.19684770102

出版商:WILEY‐VCH Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractWe have performed tunnelmeasurements on evaporated tin‐films with various amounts of copper added. The tunneljunctions were evaporated and cooled down to helium temperatures in situ in a metal‐cryostat. Tin‐copper‐films, which are condensed at low temperatures, are amorphous. They have critical temperatures from 7 °K to 3,5 °K depending on the content of copper. Tunnelmeasurements indicate that the high transition temperature belongs to a superconductor with strong coupling, whereas the lower critical temperature is characteristic of a weak coupling superconductor. Structures in tunnelcharacteristics and transition‐curves indicate that a film can have several energy‐gaps and that regions with strong and weak coupling can exist in the films. — Describing the metal‐cryostat we point out that one can reach temperatures below 1 °K with small pumping rates by diminishing

ISSN:0003-3804    

DOI:10.1002/andp.19684770103

出版商:WILEY‐VCH Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractThe radiation of a charge moving in the field of a plane circularly polarized electromagnetic wave is discussed by the methods of classical and quantum theory both for a zeropin particle (boson) and for an electron. Such considerations allow us to analyse the role of quantum and spin effects on the radiation. It is shown that the present problem has deep analogies with the problem of the synchrotron radiation. From this point of view many physical features of COMPTON radiation are represented as simple consequences of the classical or quantum theory of synchrotron radiation.

ISSN:0003-3804    

DOI:10.1002/andp.19684770104

出版商:WILEY‐VCH Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractA statistical derivation is given of a general explicit formula for the free energy of low density plasmas, which was proposed in an earlier paper. Starting from the cluster expansion of the free energy of quantum plasmas, the generalized second virial coefficient is expressed in terms of the two particle scattering phase shifts, which are exactly known in the case of COULOMB interactions. The second virial coefficient is represented in form of a convergent series expansion in terms of the BORN interaction parameter ξ (E2/KTλ), where λ is the thermal DE BROGLIE waveleng

ISSN:0003-3804    

DOI:10.1002/andp.19684770105

出版商:WILEY‐VCH Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractAn Hand eines einfachen Modells werden Beziehungen für die Berechnung der Feldverteilung und des Spannungsabfalls in einem halbleitenden Feldemitter hergeleitet. Mit Hilfe der gewonnenen Gleichungen wird der Einsatzpunkt der Abweichung vom linearen Kennlinienverlauf für den Fall des In2S3in guter Übereinstimmung mit dem Experiment berechnet. Aus experimentellen Strom‐Spannungs‐Kennlinien für In2S3wurde die Feldabhängigkeit der Beweglichkeit und des Multiplikationsfaktors der Elektronen ermittelt. Aus dem Verlauf des Multiplikationsfaktors ergibt sich Stoßionisation als verantwortlicher Mechanismus für die Elektronenvervielfachung in einem In2S3‐Feldemitter. Es werden Hinweise auf mögliche Verbesserungen der Th

ISSN:0003-3804    

DOI:10.1002/andp.19684770106

出版商:WILEY‐VCH Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractThe influence of paramagnetic centres on nuclear magnetic relaxation (nmr) will be discussed for some characteristic electron spin resonance spectra with respect to a determination of thermal correlation times and structure parameters from nmr measurements. LORENTZ‐ and GAUSS‐shaped homogeneously and inhomogeneously broadened esr lines as well as esr multiplets are investigated. Methods for deriving the quantities of interest are given.Finally the influence of an anisotropy of the spectroscopic splitting factor is shown to be negligible in first order using the formula given by STERNLI

ISSN:0003-3804    

DOI:10.1002/andp.19684770107

出版商:WILEY‐VCH Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractA method is given for the approximate calculation of the internal field of dielectrics. The applicability is proved for a cylindrical dielectric by measuring the resonant frequency shift occuring, when the samples are inserted into a region of maximum electric field of a cavity resonator.

ISSN:0003-3804    

DOI:10.1002/andp.19684770108

出版商:WILEY‐VCH Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractUsing the quantum mechanical equations describing the laser process we calculate the photon number and the amplitude fluctuations of the laser radiation for the stationary case, if the atomic frequencies are assumed to be distributed inhomogeneously in form of a LORENTZ line. It is shown, that, on principle, the results in comparision with the case of homogeneously broadened atomic line are unchanged. However, the photon number and therefore especially the threshold condition for the laser effect as well as the amplitude fluctuations are changed quantitatively in general due to the dependence of the line width 2ϵ of the LORENTZ line

ISSN:0003-3804    

DOI:10.1002/andp.19684770109

出版商:WILEY‐VCH Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractThe central properties of the usual variational formulations of EINSTEIN's general theory of relativity are sketched and a more general variational formulation is introduced, which is more appropriate to the geometric foundations of the theory. In particular, this formulation leads to the BIANCHI identities in their non‐contracted form following in consequence of a general invariance property. This invariance property of the general variational principle relates to transformations (not, in general, coordinate transformations) that contain arbitrary fifth (or third) order tensor “generators”. These results can be interpreted as implying that the variational principle introduced here admits an “extended principle of general covariance” (i.e., a covariance principle more general than the usual principle relating to general coordinate covariance). Some of the formal implications of these results as well as their connection with general coordinate covariance are discussed briefly. In particular these results point to the existence of a fundamental transformation theory connecting all of the RIEMANNian spacetimes of general r

ISSN:0003-3804    

DOI:10.1002/andp.19684770110

出版商:WILEY‐VCH Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractZur Ermittlung der Spinwellendämpfung von Magnesium‐, Mangan‐ und Magnesium‐Mangan‐Ferriten wurde die Parallelfeld‐Pumptechnik bei 9,37 GHz herangezogen. Die im Temperaturbereich von −150 °C bis 300 °C erzielten Ergebnisse zeigen, daß die Anisotropie der Spinwellendämpfung für kleine Wellenzahlen bei Magnesiumferrit unterhalb Raumtemperatur und bei Magnesium‐Mangan‐Ferrit unterhalb 150 °C beträchtlich ist. In dem Ausdruck für die Abhängigkeit der Spinwellendämpfung von den Richtungskosinus des Magnetisierungsvektors bezüglich der Kristallachsen ist dann die Konstante vor dem biquadratischen Term kleiner als die vor dem Glied sechster Potenz in den Richtungskosinus. Der anisotrope Teil der Relaxation verschwindet bei allen Ferriten in einem Temperaturbereich, in dem auch die Kristallenergie klein wird. Nur in Mg‐ und Mg‐Mn‐Ferriteinkristallen ist oberhalb Raumtemperatur ein Anstieg des isotropen Teils der Dämpfung zu verzeichnen. Da bereits bei 200 °C im Mg‐Ferrit ein Platzwechsel von Mg‐Ionen möglich ist, ist das Anwachsen der isotropen Dämpfung damit in Verbindung zu bringen. Die Spinwellendämpfung von Mangan‐ und Magnesium‐Mangan

ISSN:0003-3804    

DOI:10.1002/andp.19684770111

出版商:WILEY‐VCH Verlag    

年代:1968

数据来源: WILEY