Study of optical properties and collective oscillations in new solid-state materials as a function of temperature using infrared and Raman techniques Semiannual report, 1 Aug. 1968 - 31 Jan. 1969

Optical properties and electronic transitions in solid crystals as function of temperature using infrared and Raman technique

The Raman spectra of PbTiO sub 3 and solid solutions of NaTaO sub 3-KTaO sub 3 and KTaO sub 3-KNbO sub 3

Raman spectra of lead titanium trioxide and solid solutions of sodium tantalum trioxide-potassium tantalum trioxide and potassium niobium trioxid

Far Infrared Spectroscopy

Contains reports on two research projects

A study of the usefulness of Skylab EREP data for earth resources studies in Australia

There are no author-identified significant results in this report

Control law parameterization for an aeroelastic wind-tunnel model equipped with an active roll control system and comparison with experiment

Nominal roll control laws were designed, implemented, and tested on an aeroelastically-scaled free-to-roll wind-tunnel model of an advanced fighter configuration. The tests were performed in the NASA Langley Transonic Dynamics Tunnel. A parametric study of the nominal roll control system was conducted. This parametric study determined possible control system gain variations which yielded identical closed-loop stability (roll mode pole location) and identical roll response but different maximum control-surface deflections. Comparison of analytical predictions with wind-tunnel results was generally very good

In-Plane Magnetolumnescence of Modulation-Doped GaAs/AlGaAs Coupled Double Quantum Wells

In-plane magnetic field photoluminescence spectra from a series of GaAs/AlGaAs coupled double quantum wells show distinctive doublet structures related to the symmetric and antisymmetric states. The magnetic field behavior of the upper transition from the antisymmetric state strongly depends on sample mobility. In lower mobility samples, the transition energy shows an $\cal N$-type kink with fields (namely a maximum followed by a minimum), whereas higher mobility samples have a linear dependence. The former is due to a homogeneous broadening of electron and hole states and the results are in good agreement with theoretical calculations.Comment: 3 pages, 4 figures, submitted to Appl. Phys. Let

The study of optical properties and collective oscillations in new solid state materials as a function of temperature using infrared and Raman techniques Annual report, 15 May 1969 - 14 May 1970

Optical properties and lattice vibrations of new solid state materials studied by infrared and Raman technique

A possible explanation for the inconsistency between the Giotto grain mass distribution and ground-based observations

Giotto measured the in situ Halley dust grain mass distribution with 2 instruments, Particle Impact Analyzer and Dust Impact Detection System (DIDSY), as well as the total intercepted mass from the deceleration of the spacecraft (Giotto Radio-Science Experiment, GRE). Ground based observations made shortly before encounter have fluxes much higher than would be predicted from Giotto data. It is concluded that Giotto DIDSY and GRE data represent observations of dust originating from a narrow track along the nucleus. They are consistent with ground based data, if assumptions are made about the level of activity along this track. The actual size distribution that should be used for modeling of the whole coma should not include the large mass excess actually observed by Giotto. Extrapolation of the small grain data should be used, since for these grains the velocity dispersion is low and temporal changes at the nucleus would not affect the shape of the mass distribution

Optical and Infrared Spectroscopy

Contains report on one research project

Indicators for comparing performance of irrigated agricultural systems

Irrigated farming / Irrigation systems / Indicators / Performance indexes / Financing / Crop production / Water demand / Water requirements / Prices