Principles and Applications of ESR Spectroscopy

Book Preface

ESR or Electron Spin Resonance is a spectroscopic method for studies of paramagnetic species. Species of this kind are of interest both from fundamental viewpoints and for a broad range of applications in materials and polymer sciences, physical chemistry and chemical physics, bio-chemistry and medicine, catalysis and environmental sciences, radiation dosimetry and geological dating, as well as radiation physics and chemistry. The magnetic properties, mainly attributed to the electron spin, can be employed to determine both the structure (at a molecular level) and the amount of paramagnetic species in a sample with the ESR method. This method has been presented from different viewpoints in the past. Previous monographs on ESR spectroscopy have focused on the technique as such, while the general textbooks in physics, chemistry or spectroscopy only briefly explain the applications, which are mainly presented in specialist reviews and in the original literature. The present book is based upon the authors’ long experience of teaching the subject to a mixed audience, with backgrounds ranging from physics to biology. It aims bothat providing the principles of continuous wave and pulsed ESR techniques and to illustrate the potential of the method by examples of applications. The principles of ESR, multi-resonance and pulsed ESR methods, the analysis of spectra, and multifrequency and high field ESR techniques treated in the first four chapters are thus followed by five chapters exemplifying recent applications in molecular science, in catalysis and environmental science, in polymer science, in spin labeling and molecular dynamics, and in quantitative ESR.

Theoretical derivations are in general left out, as they are presented repeatedly in previous works. The necessary theory is instead illustrated by practical examples from the literature. Commonly used computer codes to evaluate experimental ESR data are described with examples. Internet addresses to download the software are given, whenever possible. Formulae employed in those programs are reproduced in appendices, when the original literature references are not easily available. The theory and the application parts are to a large extent independent of each other to allow study of a special subject. For reasons of easy access of data and diagrams several examples from the authors’ own work were employed to illustrate certain applications. Exercises included in the theoretical part are mainly concerned with spectra interpretations, as this is the key issue in the analysis of experimental data.

Our intention has been to prepare a textbook with the following issues in mind:
1. The book “Principles and applications of ESR spectroscopy” is for students and scientists planning to use the method without necessarily becoming experts. The book provides sufficient knowledge to properly apply the technique and to avoid mistakes in the planning and performance of the measurements.
2. The theoretical part is adapted for a non-specialist audience. Derivations of wellknown formulae are left out. The non-specialist does not want the derivations, while the physicist does not need them. The necessary theory is instead illustrated by practical examples from the literature. The potential of the method is demonstrated with applications selected from the authors’ wide experience.
3. Commonly used software to evaluate experimental ESR data is described with examples. Addresses to download the software are given.