Faraday Measurements Research Articles

Variation according to Latitude of the Electron Content of the Ionosphere near the Auroral Zone

SOME evidence has been obtained from single-frequency Faraday measurements using the satellite 1963–49C, reported by Liszka and Taylor1, that the sub-satellite electron content, nt, of the ionosphere at high latitudes may consist of two components. The first component, which decreases gradually with increasing latitude, is probably produced by ultra-violet radiation from the Sun; the second, irregular, component seems to dominate at latitudes greater than 65° N. It was suggested that the latter could either be produced by low-energy corpuscular radiation, or that it could be a manifestation of transport processes. Some more accurate measurements of the electron content at high latitudes, obtained from differential Faraday observations of the multifrequency beacon satellite S–66 (1964–64A), now show that the first explanation of the irregular component seems more plausible.

Radio Propagation Measurements of the Earth's Magnetospheric Wake.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Radio Propagation Measurements of the Earth's Magnetospheric Wake. Staff, CenterRadar Astronomy Abstract Eshleman.) Simultaneous radar echoes from the moon at 25 and 50 Mc/sec have been used to obtain differential group delay and dispersive Doppler measurements of the cislunar medium. For a single 2.5-sec echo, the accuracy of these two measurements is about 5 ~~~sec and 0.1 cps, corresponding to an uncertainty of *1016 m-2 and *101a m-2 sec-1 for the columnar electron density between the earth and the moon, and its time rate of change. Faraday polarization measurements are also used to subtract the near-earth ionospheric effects from the totals so as to obtain information about the magnetosphere, the magneto spheric wake, and the interplanetary medium between the earth and the moon. It appears that while the interplanetary density is quite low by comparison, the electron density in the magneto spheric wake of the earth is on the order of 200 cm-3. It also appears that the wake and the shock front created by the interaction of the earth with the solar wind must extend at least as far as the moon, with the shock meeting the lunar orbit at about 1200 from the earth-sun line. Publication: The Astronomical Journal Pub Date: 1965 DOI: 10.1086/109842 Bibcode: 1965AJ.....70T.692S full text sources ADS |

Infra-red Faraday Rotation and Free Carrier Absorption in Bi2Te3

The Faraday rotation at wavelengths in the range 8-15 μ has been measured on several n- and p-type single crystals of Bi2 Te3 using a magnetic field of 17 koersteds. The results are interpreted as the sum of rotations arising from free carriers and interband transitions. The latter appear to be sensitive to the impurity content. An attempt has been made to separate the components and use the free carrier rotation to estimate the effective mass parameters. Free carrier absorption measurements in the range 8-20 μ are also reported. These lead to an independent estimate of the same effective mass parameters, showing fair agreement with the Faraday measurements. The results are discussed in the light of recent galvanomagnetic measurements on some of the crystals.

On the splitting of the ground state of Ni ++ in Ni SiF 6·6H 2O

A summary is given of calculations on nickel fluosilicate which to a large extent reconcile tfie Stark splittings obtained from microwave spectra by Penrose and Stevens with the Faraday measurements of Becquerel and Van den Handel, and with the adiabatic demagnetisation data of Benzie and Cooke. The reconciliation is achieved by including suitable amounts of isotropic and anisotropic exchange. On the other hand the case of the hydrated nickel sulphates is much less satisfactory. Calculations made by L. Corliss show that the model of the crystalline field employed successfully by Krishnan and by Polder for hydrated sulphates of copper fails for those of nickel.

On the Paramagnetic Rotation of Tysonite

It is shown both theoretically and by examination of the Leiden experimental data on Ce${\mathrm{F}}_{3}$ and tysonite that in rare earth compounds the Verdet constant $V$ should exhibit the same dependence upon temperature as does the magnetic susceptibility $\ensuremath{\chi}$, even when Curie's law is not obeyed. In consequence of the similarity in the mode of variation with temperature for $V$ and $\ensuremath{\chi}$, existing data on the temperature variation of $\ensuremath{\chi}$ can be considerably enhanced by drawing upon the Faraday measurements of Becquerel and de Haas. In particular, information concerning the $\ensuremath{\chi}'\mathrm{s}$ for individual crystallographic axes thus becomes available in tysonite and the tests of calculations of the susceptibility with crystalline potentials become correspondingly severe. The triclinic field proposed by Kramers for tysonite does not appear to account for the behavior of individual principal susceptibilities, although adequate for the mean characteristic of a crystal powder. It is shown that somewhat better agreement with experiment can be achieved by assuming tentatively that the local field has rhombic symmetry, with three possible orientations for the rhombic axes differing from each other by 120\ifmmode^\circ\else\textdegree\fi{}, so that all told the crystal has the desired hexagonal symmetry. Such staggered rhombic fields are compatible with Oftedal's x-ray analysis of the crystallographic structure of tysonite, except that the deviations of the fields from axial character seem rather large.