Using UV absorbance spectroscopy in determining sublimation rates has the advantage of eliminating the surface area from the rate of mass loss equation. In addition, most importantly, the relatively small scanned area ensures extremely accurate
Authors:P. Grant, P. Robouch, R. Torres, and R. Silva
Instrumentation has been developed to perform uv-vis-nir absorbance measurements remotely and at elevated temperatures and pressures. Fiber-optic spectroscopy permits the interrogation of radioactive species within a glovebox enclosure at temperatures ranging from ambient to >100 °C. Spectral shifts as a function of metal-ligand coordination are used to compute thermodynamic free energies of reaction by matrix regression analysis. Pr3+ serves as a convenient analog for trivalent actinides without attendant radioactivity hazards, and recent results obtained from 20–95 °C with the Pr-acetate complexation system are presented. Preliminary experimentation on Am(III) hydrolysis is also described.
A Gamma Spectroscopy Logging System (GSLS) has been developed to study sub-surface radionuclide contamination. The absolute
counting efficiencies of the GSLS detectors were determined using cylindrical reference sources. More complex borehole geometries
were modeled using commercially available shielding software and correction factors were developed based on relative gamma-ray
fluence rates. Examination of varying porosity and moisture content showed that as porisity increases, and as the formation
saturation ratio decreases, relative gamma-ray fluence rates increase linearly for all energies. Correction factors for iron
and water cylindrical shields were found to agree well with correction factors determined during previous studies allowing
for the development of correction factors for type-304 stainless steel and low-carbon steel casings. Regression analyses of
correction factor data produced equations for determining correction factors applicable to spectral gamma-ray well logs acquired
under non-standard borehole conditions.
Authors:F. Bronson, V. Atrashkevich, G. Geurkov, and B. Young
To properly interpret the quality of a gamma-spectroscopy measurement, an uncertainty estimate must be made. The uncertainty
in the efficiency calibration is the dominant component to the total propagated measurement uncertainty for many types of
measurements. Any deviations between the as-calibrated geometry and the as-measured geometry contribute to the total uncertainty.
A mathematical technique has been developed to evaluate the variations between calibration and measurement conditions. A sensitivity
analysis mode identifies those variables with the largest contribution to the uncertainty. The uncertainty mode uses probabilistic
techniques for the combined variables to compute average efficiency and uncertainty, and then to propagate those values with
the gamma-spectroscopic analysis into the final result for that sample.
formed during the calcination of sulfur-rich calcareous oil shales from the Negev deposits were analyzed using FT-IR spectroscopy and curve-fitting technique. These techniques allow the identification of individual thermal phases [ 10
A survey is given on the use of X-ray spectroscopy for the qualitative and quantitative analysis of samples activated by 30
MeV bremsstrahlung from an electron linear accelerator. Detection limits are calculated from the measured X-ray spectra and
compared with those for γ-ray spectroscopy. The advantages and limitations of the method are discussed. Some practical applications
of X-ray spectroscopy in nondestructive multielement analysis are quoted.
Authors:Tack-Jin Kim, Yong-Kwang Jeong, Jun-Gill Kang, Yongju Jung, Do-Hee Ahn, and Han-Soo Lee
The spontaneous reduction of Eu3+ to Eu2+ was examined when EuCl3 was added into a pyroprocessing media of LiCl molten salt at 923 K. The amount of Eu2+ was calculated by measuring the total charge consumed to oxidize Eu2+ ions to Eu3+ ions. The concentration ratio of Eu2+ to Eu3+ was estimated to be about 0.40 in the media. In addition, it is confirmed that the reduction of Eu3+ to Eu2+ is caused by the oxidation power of Cl− to Cl2. The coexistence of Eu3+ and Eu2+ in the LiCl molten salt system was examined by UV–Visible and luminescence spectroscopy. The molar absorptivities of Eu3+ and Eu2+, calculated from UV–Visible absorption spectra, were 423 and 1954 M−1 cm−1, respectively.
Authors:N. Kopelev, Yu. Perfiliev, and Yu. Kiselev
Alkaline solutions of iron compounds synthesized by anodic dissolution of metallic iron in NaOH media have been studied by Mössbauer spectroscopy. The values of the isomer shift on iron in higher oxidation states are presented. The formation of the peroxoderivatives of iron in the solutions were not fixed.
A scientometric study of communication and growth of a new development of physics, resonance ionization spectroscopy, has
been made. Formal (journal publications) and informal (talks, lecures) communication patterns have been studied. Self citation
dominates in early publications, but drops off as the field expands. Informal communication leads formal only by about a year
in time, but is much larger in number.