**Acknowledgement**

The authors would like to thank Dr. A. Kokorin for helpful discussion through many years. The collaboration of Dr. T. Hussain, Dr. D. Kattnig, Dr. B. Mladenova-Kattnig and Dr. S. Landgraf is also greatly appreciated.

Financial supports are acknowledged from different foundations: The German Science Foundation (DFG), the Volkswagen-Foundation (Hanover, Germany), the Austrian Science Foundation (FWF), the WTZ-programs from the Austrian Exchange Service (OeAD) and the Asea-Uninet Network Program for travel grants.

### **5. References**


prime candidates in ESR line broadening experiments.

Günter Grampp and Kenneth Rasmussen

Landgraf is also greatly appreciated.

Asea-Uninet Network Program for travel grants.

[2] G. Grampp and D. Kattnig, to be published.

ESR is a suitable tool for investigating the kinetics and thermodynamics of exchange reactions. Such reactions are often used to model elementary processes like electron transfer and diffusion. Electron Self- and spin exchange rate constants can be measured quite accurately and from their temperature and pressure dependencies, the corresponding activation energies and volumes can be determined. The obtained experimental data may be interpreted within the framework of the appropriate theories, e.g. Marcus theory in the case

Due to their great stability and the relative simplicity of their ESR spectra, nitroxides are

*Institute of Physical and Theoretical Chemistry, Graz University of Technology, Graz, Austria* 

The authors would like to thank Dr. A. Kokorin for helpful discussion through many years. The collaboration of Dr. T. Hussain, Dr. D. Kattnig, Dr. B. Mladenova-Kattnig and Dr. S.

Financial supports are acknowledged from different foundations: The German Science Foundation (DFG), the Volkswagen-Foundation (Hanover, Germany), the Austrian Science Foundation (FWF), the WTZ-programs from the Austrian Exchange Service (OeAD) and the

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Field Modulation in EPR Spectroscopy. Appl. Magn. Reson. 1: 483-496.

Practical Applications. New York: Wiley-Interscience. 664 p.

Techniques. New York: Dover Publications. 780 p.

**4. Conclusion** 

of electron transfer.

**Author details** 

**Acknowledgement** 

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