Photothermal Deflection Spectroscopy Investigations of Uranium Electrochemistry - II

1993 ◽  
Vol 333 ◽  
Author(s):  
James D. Rudnicki ◽  
Richard E. Russo
Keyword(s):  
Optical Absorption ◽  
Saturated Calomel Electrode ◽  
Sample Surface ◽  
Oxidation Potential ◽  
Dissolution Mechanism ◽  
Concentration Gradients ◽  
Photothermal Deflection Spectroscopy ◽  
Photothermal Deflection ◽  
Oxide Electrochemistry

ABSTRACTPhotothermal Deflection Spectroscopy (PDS) has been applied to the study of uranium oxide electrochemistry. PDS measures the optical absorption of the sample surface and concentration gradients formed in the electrolyte. Both of these measurements are performed in situ under dynamic conditions. The combination of these two measurements provides information that can be used to infer the mechanism of the UO2 surface chemistry. These studies of the uranium dissolution mechanism are performed in pH 10.5 sodium sulfate electrolytes at 22°C. The electrolytes are free from oxygen, and complexing species. Our results suggest that dissolution of UO2 can occur at oxidizing potentials as low as -300 mV vs. saturated calomel electrode (SCE). The optical absorption and concentration gradient results provide evidence for a substantial surface change that occurs at an oxidation potential of +300 mV. The results show that the surface layer formed by this change dissolves slowly by a non-electrochemical reaction.

Photothermal Deflection Spectroscopy Investigations of Uranium Electrochemistry

1992 ◽  
Vol 294 ◽  
Author(s):  
James D. Rudnicki ◽  
Richard E. Russo
Keyword(s):  
Optical Absorption ◽  
Reaction Mechanisms ◽  
Uranium Oxide ◽  
Electrochemical Dissolution ◽  
Concentration Gradients ◽  
Photothermal Deflection Spectroscopy ◽  
First Results ◽  
Photothermal Deflection ◽  
Oxide Electrochemistry ◽  
Insight Into

ABSTRACTPhotothermal Deflection Spectroscopy (PDS) has been successfully applied to the study of uranium oxide electrochemistry. A brief description of PDS and preliminary results that demonstrate the technique are presented. Concentration gradients formed at the electrode surface are measured by this technique. The gradients give insight into the reaction mechanisms. There is some evidence of the initiation of non-electrochemical dissolution of the uranium oxide. Optical absorption by the uranium oxide is measured by PDS and the first results indicate that the absorption of the surface does not change during electrochemical experiments. This result is contrary to literature measurements of bulk samples that indicate that the optical absorption should be strongly changing.

An Investigation of Photo-Induced Degradation by Means of Photothermal Deflection Spectroscopy

1987 ◽  
Vol 95 ◽  
Author(s):  
M. S. Bennett ◽  
S. Wiedeman ◽  
J. L. Newton ◽  
K. Rajan
Keyword(s):  
Optical Absorption ◽  
Fermi Level ◽  
Single Peak ◽  
Defect States ◽  
Hydrogenated Silicon ◽  
Photothermal Deflection Spectroscopy ◽  
Amorphous Hydrogenated Silicon ◽  
Measured Absorption ◽  
Photothermal Deflection

AbstractAbsorption measurements of as deposited and photodegraded intrinsic amorphous hydrogenated silicon films were made using photothermal deflection spectroscopy (PDS). The films were light-soaked in situ using HeNe laser light to simulate AM1 illumination. An increase in subbandgap absorption occurred predominantly near energies of 1.2eV. A simple model was developed in which a density of states function is hypothesized and the resulting optical absorption at subgap energies is calculated. The measured absorption could be well matched in all cases by assuming a single peak of defect states at or slightly below the Fermi level. Further, the observed changes in optical absorption due to degradation could be modeled by increasing the density of the single peak of defect states and moving the Fermi level towards the valence band.

scholarly journals Subgap Absorption in Conjugated Polymers

1991 ◽  
Vol 228 ◽  
Author(s):  
M. Sinclair ◽  
C. H. Seager ◽  
D. McBranch ◽  
A. J. Heeger ◽  
G. L. Baker
Keyword(s):  
Optical Absorption ◽  
Conjugated Polymers ◽  
Absorption Edge ◽  
Spectral Region ◽  
Absorption Coefficients ◽  
Photothermal Deflection Spectroscopy ◽  
Integrated Optical ◽  
Integrated Optical Devices ◽  
Photothermal Deflection ◽  
Sample Age

ABSTRACTAlong with χ(3), the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10-5, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of “transparent” materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly[1,4-phenylenevinylene] (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm-1 to 10 cm-1. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration or fluorination.

Measurement of optical absorption in single quantum wells using photothermal deflection spectroscopy

1985 ◽  
Vol 47 (6) ◽  
pp. 591-593 ◽  
Author(s):  
A. F. S. Penna ◽  
Jagdeep Shah ◽  
A. E. DiGiovanni ◽  
A. Y. Cho ◽  
A. C. Gossard
Keyword(s):  
Optical Absorption ◽  
Quantum Wells ◽  
Single Quantum ◽  
Photothermal Deflection Spectroscopy ◽  
Photothermal Deflection
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