Hall and Kerr Effects at Microwave Frequencies

Abstract

The prepared sources were placed in an aluminum shelf arrangement 4 at a distance of 1 cm from the thin mica window (2.8 mg/cm 2 ) of a Victoreen (model V G 15) counter. The initial intensities of the sources were 11,000 c/m for C 14 and 9300 c/m for S 35 . Absorption curves were obtained in the customary manner by observing the activity through aluminum foils of varying thickness placed between the source and the counter. Feather analyses of the absorption curves were made using the absorption curve of the jS-radiations of UX 2 (rather than Ra E) as a standard. The Feather plots are presented in Fig. 1.The extrapolated ranges obtained are 28.5 ±0.5 mg/cm 2 for C 14 and 31.7 ±0.5 mg/cm 2 for S 36 , in good agreement with the previous determinations. 1 It will be noticed, however, that over the whole range of absorption there is a constant ratio between the two Feather plots, i.e., the shapes of the absorptions curves for C 14 and S 38 are identical. The difference in the absorption curves previously reported 1 was probably due to the use of sources of appreciable thickness which exerts a marked effect on the lower energy electrons in the initial portions of the curves. To the extent that the shape of an absorption curve is indicative of the shape of the energy spectrum, 3 -5 the curves of Fig. 1 may be taken to indicate that the shapes of the energy spectra of C 14 and S 35 are essentially identical, at least for energies greater than about 50 kev. (Electrons of energy less than this value are stopped by the external absorption of 4 mg/cm 2 due to window and air.) This is a rather interesting result in view of the great difference in the half-lives of C 14 (5100 years) and S 36 (87 days).In a recent investigation of the 0-spectra of C 14 and S 36 using a magnetic lens spectrometer, Berggren and Osborne 6 have found that the energy distributions of both spectra are of the same allowed shape for energies above 40 kev. From a similar investigation with a magnetic spectrometer, Langer, Cook, and Price 7 report, however, that the j8spectra of C 14 and S 36 differ slightly in shape.

Microwave hall mobility studies on polymer–metal oxide nanocomposites

“…The microwave Hall effect was first observed by Cooke,1 who used it to determine the carrier mobility in semiconductors. Several workers developed this technique further by using a circular bimodal cavity 2–6.…”