Physics Commons^™

Absorption Cross-Sections Of Sodium Diatomic Molecules, Zeng-Shevan Fong

Physics Theses & Dissertations

The absorption cross sections of sodium dimers were studied using a heat pipe over operating in the non-heat-pipe mode. Three wavelength regions were observed. They are in the red, the green-blue, and the near ultraviolet regions. The absorption cross section depends on the wavelength of the incident light. Representative peak values for the v"=0 progression in the red and green-blue regions are 2.59 A sup 2 (average value) and 11.77 A sup 2 (T_ave=624 K). The value for the C greater than X transitions is several tenths A sup 2. The cross sections were measured from absorption spectra …

Minimal Norm Constrained Interpolation, Larry Dean Irvine

Mathematics & Statistics Theses & Dissertations

In computational fluid dynamics and in CAD/CAM a physical boundary, usually known only discreetly (say, from a set of measurements), must often be approximated. An acceptable approximation must, of course, preserve the salient features of the data (convexity, concavity, etc.) In this dissertation we compute a smooth interpolant which is locally convex where the data are locally convex and is locally concave where the data are locally concave.

Such an interpolant is found by posing and solving a minimization problem. The solution is a piecewise cubic polynomial. We actually solve this problem indirectly by using the Peano kernel theorem to …

Feasibility Studies Of Conversion Electron Mossbauer Spectroscopy (Cems) Of Iron-Doped Inp, Edward Agyekum

Physics Theses & Dissertations

An electron detector for conversion electron Mossbauer spectroscopy (CEMS) has been designed and built. Tests have been performed to study the effects on the electron detector resolution with respect to high anode voltage, He/CH₄ gas flow rate, and counting rate. These parameters have been optimized to detect the 7.3 keV conversion electrons emitted following resonant absorption of the 14.4 keV source gamma-rays associated with the Mossbauer effect using ⁵⁷Fe nuclei. CEMS spectra have been obtained using standard ⁵⁷Fe enriched and natural iron samples. CEMS spectra and Mossbauer transmission spectra have also been obtained for iron-compensated InP (InP:Fe) …