ESR instrument composition

Simplified Principle of Electron Spin Resonance (ESR)

With an ESR instrument, a static magnetic field and microwaves are used to observe the behavior of the unpaired electrons in the material being studied. The study of the behavior of the electrons in a sample gives information about the condition of the sample.

ESR is used to observe and measure the absorption of microwave energy by unpaired electrons in a magnetic field.

What we can learn from ESR

ESR measurements afford information about the existence of unpaired electrons, as well as quantities, type, nature, surrounding environment, and behavior.

• The ‘g’ value, which reflects the orbit level occupied by the electron
• Line width, which is related to the transverse relaxation time
• Saturation characteristics, which are related to the longitudinal relaxation time
• Number of unpaired electrons
• Hyperfine structure : hfs, which represents the interactions between electrons and nuclei
• Fine structure: fs, which represents the interactions between electron and electron
• Exchange interactions reflecting the exchanges between electrons

Applications of ESR

• Electron state, such as magnetic materials and semiconductors
• Electron state of semiconductor lattice defects and impurities (dopants)
• Structure of glass and amorphous materials
• Tracking of catalytic reactions, changes in charge state
• Photo-catalytic reactivity and photochemical reaction mechanisms
• Radicals of polymer polymerization processes (photo-polymerization, graft polymerization)
• Polymer resolution (photolysis, radiolysis, pyrolysis, chemical decomposition)
• Active oxygen radicals related to aging in disease in living organisms
• Oxidative degradation of lipids (food oils, petroleum, etc.)
• Detection of foodstuffs exposed to radiation
• Measurement of the age of fossils and geological features using lattice defects