| Autor: |
E. de Boer, C. P. Keijzers, T Jansen, J. S. Wood, G. van Kalkeren |
| Rok vydání: |
1983 |
| Předmět: |
|
| Zdroj: |
Journal of Magnetic Resonance (1969). 52:211-220 |
| ISSN: |
0022-2364 |
| DOI: |
10.1016/0022-2364(83)90189-0 |
| Popis: |
The CU(IM)62+ (Im = imidazole) ion doped into the triclinic zinc host crystal Zn(Im)6Cl2 · 4H2O was reexamined with X- and Q-band single-crystal EPR spectroscopy over the temperature range 4 to 300 K. Contrary to the earlier study, which characterized this system as an example of Jahn-Teller tunneling between three tetragonally elongated configurations, it was found from our more extensive measurements, that the Cu(Im)62+ ion represents an example of strong Jahn-Teller coupling. Below the transition temperature from dynamic to static behavior, two wells in the “Mexican hat” potential energy surface are preferentially and almost equally occupied. The g and hyperfine tensors for these two sites are consistent with the tetragonally elongated geometry typically found for the static Jahn-Teller effect in CuL62+ systems. At higher temperatures the third site 1758 becomes populated leading to a near isotropic spectrum at room temperature. Measurement of the variation of g and hyperfine coupling with temperature leads to an approximate value of 100 to 150 cm−1 for the height of the barrier separating this third site from the two lower energy sites. Examination of the structure of the host crystal allows an understanding of the observed EPR behavior. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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