The microscopic ordering and macroscopic disorder spectra analysis of X-band electronic paramagnetic resonance

The correlation time and S order parameter are two important parameters to characterize the moving and distribution of the spin labeled macromolecule. It is significant to determine them simultaneously by lineshape analysis with an appropriate physics model for EPR spectrum analysis. In the present paper, the microscopic ordering and macroscopic disorder model (MOMD) was adopted to simulate the X-band EPR spectra of spin label with axial symmetric magnetic tensors. The experimental parameters were measured, and the divergence between the real values and the empirical values was analyzed. For MOMD spectra the authors proposed a criteria to select the experimental parameters. With the selected parameters, the correlation time and the internal S order parameter could be obtained simultaneously. And the valid range determined by the recognition function is presented.