Abstract: The ESR spectra of liquid samples which are acquired by ASPECT 3000 of Bruker ER-200D ESR spectrometer are transferred to IBM PC/XT. The software ESRSIMU running under DOS is programed simulating experimental ESR first-order spectrum of either mono-or multi-radical systems in solution. ESRSIMU is a fast, easy-to-use programme which allows both experimental and calculated ESR spectra to be viewed on screen at the same time. The relative concentratioll ratio of paramagnetic species contained in systems can be evaluated by simulation of multi-radical systems. In comparison with Bruker EPR 3002, the simulation of single radical executed by ESRSIMU is ca. 100 times faster.

Key words: ESR, Multi-Radical system, Simulation