Determination of Spin Concentrations in ESR Tomography as Applied for the Spatial Distribution of Spin Labels in Human Skin |
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Authors: | U Hochkirch W Herrmann R Stößer K-P Moll J Gallego Llerena M Linscheid H-H Borchert |
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Institution: | (1) Institute of Chemistry, Humboldt University of Berlin, Berlin, Germany;(2) Institute of Pharmacy, Free University Berlin, Berlin, Germany |
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Abstract: | The spectral–spatial electron spin resonance (ESR) imaging experiment provides information about the spatial and spectral
properties of the examined sample, as well as the intensity distribution. Obtaining quantitative statements of the respective
sample requires the usage of reference standards such as diphenylpicrylhydrazyl (DPPH) or charcoal. By means of ultraviolet-visible
spectroscopy a DPPH sample has been quantified to become the reference DPPH standard for the following experiments. Moreover,
charcoal together with DPPH serves as a standard to determine the spatial dimension. An ESR tomographic device has been modified
concerning the sample shaping and arranging in a TE102 resonator to allow the spatially resolved quantitative determination of spin concentrations of spin probes (S = 1/2) with an acceptable error. Only standard ESR equipment has been used except the additional gradient coils and their
computer-aided controls for recording the tomogram. The presented results, i.e., the spatially resolved determination of spin
concentrations, seem to be useful to describe, e.g., transport processes in biological objects. As a first application of
the developed method, the spatial resolution of the effect of ultraviolet irradiation on the concentration of a spin probe
in human skin could be determined. Altogether, the newly introduced method widens the field of applications of ESR spectroscopy
and tomography.
Authors' address: Werner Herrmann, Institute of Pharmacy, Free University Berlin, Kelchstrasse 31, 12169 Berlin, Germany |
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