In situ Moessbauer spectroscopy of a species irreversibly adsorbed on an electrode surface
- Case Western Reserve Univ., Cleveland, OH (USA)
The redox properties of {mu}-oxobis(iron meso-tetrakis(methoxyphenyl)porphyrin)(FeTMPP){sub 2}O, adsorbed on high-area carbon in alkaline solutions have been examined in situ by using Moessbauer spectroscopy at cryogenic temperatures. The spectrum obtained for the electrode polarized at 0.0 V vs Hg/HgO, OH{sup {minus}} yielded at 100 K a doublet with parameters resembling those of bulk crystalline (FeTMPP){sub 2}O. Similar measurements with the electrode polarized at {minus}0.9 V at the same temperature displayed in addition to the original feature two new doublets with Moessbauer parameters consistent with the presence of a high-spin ferrous (S = 2) and either a high-spin ferric (S = 5/2) or an intermediate-spin ferrous porphyrin species (S = 1). As the temperature was increased, these new features collapsed into a single doublet with an isomer shift intermediate between those observed at 100 K. Two possible models have been suggested to account for these results: (i) the formation of a mixed-valence {mu}-oxo-type porphyrin, which below the spin trapping temperature would give rise to ferrous and ferric sites, and (ii) the full reduction and dissociation of the dimer following the first electron transfer, to yield an intermediate-spin and a high-spin ferrous porphyrin.
- DOE Contract Number:
- AC02-87ER80500
- OSTI ID:
- 6046629
- Journal Information:
- Langmuir; (USA), Journal Name: Langmuir; (USA) Vol. 6:8; ISSN LANGD; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
Similar Records
Study of Vitamins and Dietary Supplements Containing Ferrous Fumarate and Ferrous Sulfate Using Moessbauer Spectroscopy
Characterization of Electronic Structure and Properties of a bis(histidine) Heme Model Complex
Related Subjects
360603* -- Materials-- Properties
656002 -- Condensed Matter Physics-- General Techniques in Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ADSORPTION
AQUEOUS SOLUTIONS
CARBON
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DISPERSIONS
ELECTRODES
ELEMENTS
EVEN-ODD NUCLEI
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INTERMEDIATE MASS NUCLEI
IRON 57
IRON ISOTOPES
ISOTOPES
LOW TEMPERATURE
MIXTURES
MOESSBAUER EFFECT
NONMETALS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PORPHYRINS
REDOX REACTIONS
SOLUTIONS
SORPTION
STABLE ISOTOPES
SURFACE PROPERTIES