Determination of the g-, hyperfine coupling- and zero-field splittingtensors in EPR and ENDOR using extended Matlab codes

The analysis of single crystal electron magnetic resonance (EMR) data has traditionally been performedusing software in programming languages that are difficult to update, are not easily available, or areobsolete. By using a modern script-language with tools for the analysis and graphical display of the data,three MatLabÒcodes were prepared to compute the g, zero-field splitting (zfs) and hyperfine coupling(hfc) tensors from roadmaps obtained by EPR or ENDOR measurements in three crystal planes.Schonland’s original method was used to compute the g- andhfc-tensors by a least-squares fit to theexperimental data in each plane. The modifications required for the analysis of thezfsof radical pairs withS = 1 were accounted for. A non-linear fit was employed in a second code to obtain thehfc-tensor fromEPR measurements, taking the nuclear Zeeman interaction of an I = ½ nucleus into account. A previouslydeveloped method to calculate the g- andhfc-tensors by a simultaneous linear fit to all data was used inthe third code. The validity of the methods was examined by comparison with results obtained experi-mentally, and by roadmaps computed by exact diagonalization. The probable errors were estimated usingfunctions for regression analysis available in MatLab. The software will be published athttps://doi.org/10.17632/ps24sw95gz.1, Input and output examples presented in this work can also be downloaded fromhttps://old.liu.se/simarc/downloads?l=en.Ó2021 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license(http://creativecommons.org/licenses/by/4.0/).

Jaar van publicatie:2021

Toegankelijkheid:Open