One-dimensional angular correlation of positron annihilation radiation spectra (ID-ACAR) from single crystals of [Fe(ptz)6] (BF4)2 and [Zn(ptz)6] (BF4)2 along the c-axis are measured in the temperature range between 23 K and 295 K. A remarkable temperature dependence of the ACAR spectra for [Fe(ptz)6](BF4)2 around the spin-crossover temperature (130K) is observed and interpreted as being due to spin-conversion of positronium atoms. This observation suggests that the positronium atoms are localized in the vicinity of the central Fe(II) ion of [Fe(ptz)6] (BF4)2. In contrast, ACAR spectra for [Zn(ptz)6](BF4)2, which shows no spin-crossover, are almost independent of temperature. No evidence for the formation of delocalized free positronium atoms is found in either sample.
|Number of pages||2|
|Journal||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|Publication status||Published - 1998 Jan|
ASJC Scopus subject areas
- Physics and Astronomy(all)