| Interactive Simulation of CW and Pulsed EPR Spectra (2007) | |||||||||||
Abstract | |||||||||||
| A general program for the computer simulation of cw electron paramagnetic resonance spectra has previously been developed [1]. This simulation package is currently being extended to include the simulation of pulsed EPR spectra. A number of different strategies have been necessary to both accurately and efficiently simulate different pulsed EPR experiments and different spin systems. For spin systems that have little anisotropy transformation to the rotating frame is effective in removing the time dependent component of the Hamiltonian allowing efficient simulation of time domain EPR spectra. With spin systems with S>1/2 and large zero field parameters this is no longer valid and an implementation of Floquet theory is necessary. The calculation time for many simulations can be greatly reduced by using ‘frequency domain’ methods.[2] A computationally efficient implementation of Floquet theory has been developed that is valid for all spin systems but converges to the rotating frame solution for simple cases. A novel method for the interactive fitting of cw EPR spectra is demonstrated. This method allows a user to directly manipulate the simulated spectra in an intuitive manner in order to achieve a fit to experimental data. Peaks in the simulated spectrum are simply dragged and dropped to align with corresponding peaks in the experimental spectrum. As the features in the spectrum itself are manipulated rather than the spin Hamiltonian parameters a detailed understanding of the relationship between two is not required by the user. The approach can also be extended to the fitting of pulsed EPR spectra using the ‘frequency domain’ approach and Floquet theory. Automated fitting of experimental spectra using this methodology is also possible | |||||||||||
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