Die optischen Konstanten des Kaliums im Wellenlängenbereich von 3650 bis 20000 Å

The optical constantsn andk of the alkali metal potassium have been measured in the wavelength region from 0·365μ to 2μ, in the solid and liquid state at temperatures between ?180° C and +85° C by the usual method of analysing intensity and polarisation of the monochromatic radiations reflected by the metals surface. The mirrorlike surfaces, free of any contamination and not distorted by any treatment, were prepared and measured in ultrahigh vacuum, the metal being purified before by careful repeated destinations in high vacuum. Values thus obtained forn, k, k ²?n ² and 2nk are listed in tables 1 and 2. Discussion of these values especially with regard to the Drude-theory of optical constants of metals is given in two subsequent communications.     

Über Fabry-Perot-Verspiegelungen aus dielektrischen Vielfachschichten für den Spektralbereich von 2350 bis 20000 Å

The production and the performance of dielectric multilayer mirrors for Fabry-Perot interferometers from 20000 Å to 2350 Å are described. Details of the evaporation apparatus and techniques are given. The optical data — reflection factor, absorption factor and flatness — are represented graphically and discussed. For all wavelength cryolite served as low refractive material. The high refractive materials used were ZnS for wavelengths from the infrared to λ>4100 Å, Sb₂O₃ for λ between 4200 Å and 3200 Å and PbF₂ for the shorter wavelengths to λ=2350 Å. For PbF₂ an exciton-band at 2190 Å has been found.     

Die Pendelvervielfachung von Sekundärelektronen im Dezimeterwellengebiet

The conditions as deduced from theory for the existence of secondary electron resonance mechanism (dynamic multiplication of secondary electrons) are tested in the decimeter wave range. A re-entrant cavity resonator is used for this the field length of which can be varied at its field maximum. For the voltage amplitude at the start of multiplication the quadratic dependence on the length of field — as postulated by theory — is completely confirmed. For the voltage amplitude at the instant of break-off the experiments, however, yield for small lengths of field higher values than calculated.     

Energieverlust und Reichweite von α-Teilchen in Bor im Energiebereich von 0,2 bis 5,3 MeV

With a scintillation spectrometer the air equivalent of boron for α-particles has been measured as a function of the energy. The boron foils (50?120 μg·cm^?2) were evaporated onto thin mica. The α-particle energy was set to between 0.2 and 5.3 MeV by letting the particles of a²¹⁰Po-α-source pass through air. With known data for the energy loss in air the range and stopping power in boron have been determined. The error of each measured datum is about 2%.