What is ESR?
ESR (Electron Spin Resonance) is a spectroscopic technique in which a sample is irradiated with microwaves and electron spin resonance is observed.
ESR detects free radicals (unpaired electrons) in a material and provides information on the environment in which the electrons exist, and ESR spectra can be used to determine the presence or absence of unpaired electrons, their quantification, and the state of the atoms around the unpaired electrons.
In principle, ESR is 700 times more sensitive than NMR (Nuclear Magnetic Resonance), which also uses a magnetic field to detect nuclear spin.
Electrons with a magnetic moment are normally in a degenerate and equal energy state, but when a magnetic field H0 is applied, the degeneracy is released and they split into two states, one parallel to the direction of the magnetic field and the other antiparallel.
This is called Zeeman splitting.
When an electromagnetic wave of frequency ν is applied to the electron from the outside, the electron absorbs the hν and jumps to the antiparallel state above when the energy of the electromagnetic wave hν is equal to the energy interval between the two, gμBH0.
This phenomenon is called electron spin resonance.
Zeeman splitting : Applying a magnetic field to an electron spin causes it to split into two energy states
Energy level diagram for one electron spin and one nuclear spin placed in a magnetic field
KEYCOM's ESR/EPR Measurement Service
KEYCOM develops and manufactures ESR systems and provides evaluation services for materials.
We can also perform molecular orbital calculations (semi-empirical/nonempirical molecular orbital method: ab initio method) and density functional theory (DFT) analysis at the same time.
What does the measurement value of ESR/EPR tell us?
- The resonant magnetic field H indicates the g-value of the environment (shape and direction of the molecule) in which the electron is placed.
- Information on the relaxation of electrons from the line width (half value width)
- Quantitative analysis of the number of radicals from the integrated intensity of the peak
- Linear (Gauss type, Lorentz type): magnetic dipole interaction, superiority or inferiority of exchange interaction
- Fine structure (fs): interaction between electron spins
- Hyper fine structure (hfs): interaction between electron and nuclear spins
Ordering Information
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The Cost Estimate of ESR Test (MS-Word)
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