Heat capacity of mixed-valence 1′,1′″-diiodobiferrocenium triiodide in the 0.080–25 K range: direct observation of tunnel splitting
✍ Scribed by Motohiro Nakano; Michio Sorai; Paula M. Hagen; David N. Hendrickson
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 470 KB
- Volume
- 196
- Category
- Article
- ISSN
- 0009-2614
No coin nor oath required. For personal study only.
✦ Synopsis
The heat capacity of the mixed-valence complex l', 1"'diiodobiferrocenium triiodide, [ (&H,IFe), ( CIOH8) ] +I?, has been measured by adiabatic calorimetry between 80 mK and 25 K. A Schottky anomaly centered around 0.6 K was found and interpreted in terms of a tunnel splitting of the vibronic ground state of the cation, which leads to a molecular quantum paraelectric (MQP). The splitting was determined to be z 1 cm-' which corresponds to an intermolecular electron transfer rate of % 0.7 X I O9 s-'. The mean field theory by Kambara and Sasaki has been applied to determine the phase diagram. The MQP state is stable unless the cation-anion interaction exceeds z 12.3 cm-'. The possibility of a phase transition in the MQP under some external fields has been discussed.