https://doi.org/10.1140/epjd/s10053-022-00403-9
Regular Article - Molecular Physics and Chemical Physics
Estimation of distance-distribution probabilities from pulsed electron paramagnetic resonance (EPR) data of two dipolar interaction coupled nitroxide spin labels using doubly rotating frames and least-squares fitting
Physics Department, Concordia University, 7141 Sherbrooke St. West, H4B 1R6, Montreal, QC, Canada
Received:
19
January
2022
Accepted:
17
April
2022
Published online:
19
May
2022
A method, based on the doubly rotating frame (DRF) technique to calculate the basis DEER (Double Electron–Electron Resonance) signals [Physica B: Condensed Matter, 625, 413,511 (2022)] accurately by numerical techniques over a range of 
values, where is the distance between the two nitroxides in a biradical in a biological system, has been exploited to calculate the probabilities of distance distribution, 
by the use of Tikhonov regularization. It is demonstrated here by applying it to the data reported by Lovett et al. [J. Magn. Reson., 223, 98–106 (2012)] on a sample of bis-nitroxide nanowire, P1, in deuterated ortho-terphenyl solvent with 5% BnPy (d14-oTP/BnPy) in semi-rigid state. An improvement in the agreement of the calculated signal with respect to the experimental signal and thus in the probabilities of the distance distribution, 
, so obtained, is found, as compared to that obtained using the kernel signals based on analytical expressions.
© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2022
