- Tytuł:
- EPR Study of Ammonium Nitrate Doped with Copper(II) Ions
- Autorzy:
-
Wojtowicz, W.
Więckowski, A. B. - Powiązania:
- https://bibliotekanauki.pl/articles/2043645.pdf
- Data publikacji:
- 2005-08
- Wydawca:
- Polska Akademia Nauk. Instytut Fizyki PAN
- Tematy:
-
61.50.Ks
76.30.Fc - Opis:
- This work is devoted to a study of the structural changes in a single crystal of ammonium nitrate, NH$\text{}_{4}$NO$\text{}_{3}$, doped with copper(II) cations by electron paramagnetic resonance. Ammonium nitrate crystallizes at atmospheric pressure in several polymorphic forms, phase VII → V → IV → III → II → I → melt, with transition temperatures of 103 K, 255 K, 305 K, 357 K, 398 K, and 443 K, respectively. The aim of our work was to study the temperature phase transition V → IV at about 255 K using electron paramagnetic resonance technique. The electron paramagnetic resonance spectra were performed using an X-band spectrometer with microwave frequency of 9.4 GHz and magnetic modulation of 100 kHz in the temperature range of 153-296 K. For a single crystal the angular dependence of the copper(II) electron paramagnetic resonance spectra was measured at 293 K and 168 K. The anisotropic behaviour measured at 293 K points to the existence of one kind of two equivalent copper(II) complexes with inverse g and A tensors. A second pair of equivalent complexes also with inverse g and A tensors was observed. The minimal values of g-factors correspond to the maximum values of A. The angular dependence taken at 168 K shows the existence of two types of non-equivalent copper complexes which differ in comparison with the complexes observed at room temperature. The temperature dependence of the intensities of hyperfine structure lines for all copper(II) complexes observed shows a phase transition V → IV occurring in the temperature range of 237-246 K with a hysteresis. One of the hyperfine structure lines of a copper(II) complex measured at low temperatures shows a superhyperfine structure with line intensities 1:2:3:2:1 originating from the interaction of the copper $\text{}^{63,65}$Cu (I=3/2) nucleus with two $\text{}^{14}$N (I = 1) nuclei of two ammonia, NH$\text{}_{3}$, ligand molecules.
- Źródło:
-
Acta Physica Polonica A; 2005, 108, 2; 395-401
0587-4246
1898-794X - Pojawia się w:
- Acta Physica Polonica A
- Dostawca treści:
- Biblioteka Nauki
Artykuł