EasySpin is a MATLAB toolbox for simulating and fitting Electron Paramagnetic Resonance (EPR) spectra. It supplements the numerical and visualisation power of MATLAB with the best computational methods devised by EPR spectroscopists. EasySpin runs on Windows, Linux and Mac, and is available free of charge.

    Current version: 3.1.1 (10 Dec 2009)   [download]

EasySpin can simulate a wide range of EPR spectra. For all simulations, interactive least-squares fitting using hybrid methods based on Simplex, Levenberg-Marquardt and genetic algorithms are possible.

	Solid-state cw EPR spectra powders and crystals (with space groups) arbitrary number of electron and nuclear spins all interactions, including high-order operators and nuclear quadrupole matrix diagonalization and perturbation methods broadening models: g, A and D strain, unresolved hyperfine splittings non-equilibrium populations perpendicular and parallel detection mode
	Pulse EPR two- and three-pulse ESEEM, HYSCORE user-defined sequences arbitrary number of nuclear spins high-spin systems nuclear quadrupole interaction included built-in processing
	Slow-motion cw EPR spectra one unpaired electron, several nuclei axial and rhombic rotational diffusion tensor arbitrary tensor orientations orientational potential single-orientation and MOMD models
	Solid-state ENDOR spectra powders and crystals (with space groups) arbitrary number of nuclei, includes nuclear quadrupole hyperfine enhancement built-in orientation selection matrix diagonalization and perturbation methods
	Isotropic cw EPR spectra one unpaired electron, arbitrary number of nuclei resonance fields are exact (no perturbation formulae) automatic determination of magnetic field range
	Fast-motion cw EPR spectra one unpaired electron, arbitrary number of nuclei user provides rotational correlation time and tensor anisotropies, line widths are automatically computed includes effects from nuclear quadrupole interaction

EasySpin also provides a variety of other tools:

• Basic spin physics: spin operators, Stevens operators, spin Hamiltonians with arbitrary number of electron and nuclear spins, angular momentum.
• Utilities: line shapes, Euler angle utilities, orientational grids, data import from all common EPR file formats (BES3T, ESP, Varian), nuclear isotope database, field/frequency/g value conversion
• Data analysis: RC filtering, field-modulation, cross-term averaged FFT, moving average, many apodization windows, baseline correction
• Resonances: ENDOR and cw EPR resonance line computations, energy level diagrams
• Time-domain: support for propagators and density matrix evolutions.

EasySpin is written and maintained by Stefan Stoll, currently at the University of California, Davis.

For bug reports, inquiries, and suggestions, contact the Before submitting bugs, download the latest version and verify them.