Del R. Lawson

Near‐IR Absorption Spectra for the Buckminsterfullerene Anions: an Experimental and Theoretical Study

Abstract : C60 can exist in a number of oxidation states including C60(1-), C60(2-) and C60(3-). Ultraviolet-visible absorption data have been described. Near-infrared absorption data have not been presented for any of the oxidation states of C60. we have discovered that this is a serious oversight, because near-IR absorption peaks which are unique to C60(1-) C60(2-) and C60(3-) are observed upon one, two and three electron electrochemical reductions of C60. We have rationalized the energies and intensities of these electronic absorptions based on modifications of the known molecular orbital diagram for C60. The near-IR absorptions reported here should provide a clear and unambiguous route for determining the oxidation state of C60 in solution.

Use of a coulometric assay technique to study the variables affecting deuterium loading levels within palladium electrodes

Abstract We report in this paper measurements of hydrogen (H) and deuterium (D) loading stoichiometries in Pd electrodes. We accomplished these analyses using an electrochemical method developed for in situ determination of palladium deuteride stoichiometries. The electrochemical method quantifies the amount of deuterium incorporated into the metal lattice by collecting the charge released during the potential controlled discharge of deuterium loaded Pd electrodes. In addition, ex situ gravimetric analyses were used to confirm electrochemically measured D/Pd atom ratios. Gravimetric analyses were also used in cases where the diameter of the Pd electrode precluded the relatively slow diffusion-limited electrochemical discharge method. A variety of electrolytic factors were studied to determine what conditions, if any, promote the greatest absorption of deuterium into the Pd lattice. We observed loading values of 0.73 ± 0.02 deuterium atoms per Pd lattice atom under all the electrolytic conditions studied in LiOD and D2SO4 solutions. As found in previous studies, H/Pd values were approximately 10% higher than D/Pd values. These measurements of D/Pd stoichiometries indicate that interfacial parameters, current density, pD, charging time and surface purity have negligible effect on the maximum deuterium concentration within Pd electrodes.