T. Yokoyama et al., Photo-induced magnetized state of Co(DTBSQ)(DTBCat)(phen) center dot C6H5CH3 studied by X-ray absorption spectroscopy, CHEM P LETT, 345(3-4), 2001, pp. 272-276
A photo-induced magnetized state of Co(DTBSQ)(DTBCat)(phen) . C6H5CH3 (DTBS
Q = 3,5-di-tert-butyl-semiquinone, DTBCat = 3,5-di-tert-butyl-catechol and
phen = 1,10-phenanthroline) was investigated by Co K-edge X-ray absorption
fine structure (XAFS) spectroscopy. In the present experimental setup, abou
t 65% Co is found to stay in the trapped excited state at I I K during visi
ble-light (532 nm) irradiation. It is revealed from the X-ray absorption ne
ar-edge structure (XANES) spectra that the Cc electronic structure of the s
tate is essentially identical to that of the high-temperature (HT) phase. U
pon irradiation, one electron in DTBCat(2-) is transferred to low-spin (LS)
Co(III), yielding high-spin (HS) Co(II) and DTBSQ(-). Extended X-ray absor
ption fine structure (EXAFS) analysis provides information on the first-nea
rest neighbor N and O distances; the irradiated sample shows the average Co
-N,O distance of 1.95 +/- 0.04 Angstrom, which lies between those of low-te
mperature (1.899 +/- 0.011 Angstrom) and HT (2.081 +/- 0.021 Angstrom) phas
es, this being consistent with the XANES results. (C) 2001 Published by Els
evier Science B.V.