A Fourier transform spectrometer for visible and near ultra-violet measurements of atmospheric absorption

The development of a prototype, ground-based, Sun-pointed Michelson interferometric spectrometer is described. Its intended use is to measure the atmospheric amount of various gases which absorb in the near-infrared, visible, and near-ultraviolet portions of the electromagnetic spectrum. Preliminary spectra which contain the alpha, 0.8 micrometer, and rho sigma tau water vapor absorption bands in the near-infrared are presented to indicate the present capability of the system. Ultimately, the spectrometer can be used to explore the feasible applications of Fourier transform spectroscopy in the ultraviolet where grating spectrometers were used exclusively

The Influence of Sample and Detector Angles Upon Auger Electron Signal

The effects of the sample to incident electron beam angle and of the detector. angle on the Auger electron signal are important for quantitative Auger analysis, particularly for Auger mapping and line scans. A first approximation, single scattering, mean free path model is employed to simulate the Auger signal resulting from a range of sample and detector angles. The model is single scattering in the sense that the excitation path is taken to be a straight line into the solid. A second model approximates multiple scattering by a normal distribution of ionizing flux angles about the incident beam direction. Since spherical particles exhibit all possible surface angles, they are useful for testing the theoretical models. A coaxial electron gun/cylindrical mirror analyzer (CMA) instrument with an angle-resolved drum is employed to analyze 200μm diameter Ti spheres on a Sn substrate. The observations compare favorably with predictions of the model for Ti and O Auger signals, and the multiple scattering approximation is seen describe the results

Ion-tracer anemometer

Gas velocity measuring instrument measures transport time of ion-trace traveling fixed distance between ionization probe and detector probe. Electric field superimposes drift velocity onto flow velocity so travel times can be reduced to minimize ion diffusion effects

Coulomb field of an accelerated charge: physical and mathematical aspects

The Maxwell field equations relative to a uniformly accelerated frame, and the variational principle from which they are obtained, are formulated in terms of the technique of geometrical gauge invariant potentials. They refer to the transverse magnetic (TM) and the transeverse electric (TE) modes. This gauge invariant "2+2" decomposition is used to see how the Coulomb field of a charge, static in an accelerated frame, has properties that suggest features of electromagnetism which are different from those in an inertial frame. In particular, (1) an illustrative calculation shows that the Larmor radiation reaction equals the electrostatic attraction between the accelerated charge and the charge induced on the surface whose history is the event horizon, and (2) a spectral decomposition of the Coulomb potential in the accelerated frame suggests the possibility that the distortive effects of this charge on the Rindler vacuum are akin to those of a charge on a crystal lattice.Comment: 27 pages, PlainTex. Related papers available at http://www.math.ohio-state.edu/~gerlac

Forest Stand Mapping and Evaluation on State and Private Lands in Montana

Paper published as Bulletin 46 in the UM Bulletin Forestry Series.https://scholarworks.umt.edu/umforestrybulletin/1029/thumbnail.jp