Preprints
https://doi.org/10.5194/mr-2021-10
https://doi.org/10.5194/mr-2021-10

  26 Jan 2021

26 Jan 2021

Review status: this preprint is currently under review for the journal MR.

The decay of the refocused Hahn echo in DEER experiments

Thorsten Bahrenberg1,, Samuel M. Jahn2,, Akiva Feintuch1, Stefan Stoll2, and Daniella Goldfarb1 Thorsten Bahrenberg et al.
  • 1Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 7610001, Israel
  • 2Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
  • Equal contribution

Abstract. Double electron–electron resonance (DEER) is a pulse electron paramagnetic resonance (EPR) technique that measures distances between paramagnetic centres. It utilizes a four-pulse sequence based on the refocused Hahn spin echo. The echo decays with increasing pulse sequence length 2(τ1 + τ2), where τ1 and τ2 are the two time delays. In DEER, the value of τ2 is determined by the longest inter-spin distance that needs to be resolved, and τ1 is adjusted to maximize the echo amplitude and thus sensitivity. We show experimentally that for typical spin centres (nitroxyl, trityl, Gd(III)) diluted in frozen protonated solvents, the largest refocused echo amplitude for a given τ2 is obtained neither at very short τ1 (which minimizes the pulse sequence length) nor at τ1 = τ2 (which maximizes dynamic decoupling for a given total sequence length), but rather at τ1 values smaller than τ2. Large-scale spin dynamics simulations including the electron spin and several hundred neighbouring protons reproduce the experimentally observed behaviour almost quantitatively. They show that electron spin dephasing is driven by solvent protons via the flip-flop coupling among themselves and their hyperfine couplings to the electron spin.

Thorsten Bahrenberg et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on mr-2021-10', Janne Soetbeer, 03 Feb 2021
  • RC1: 'Comment on mr-2021-10', Mike Bowman, 03 Feb 2021
  • CC2: 'Comment on mr-2021-10: Code availability?', Nino Wili, 04 Feb 2021
  • RC2: 'Comment on mr-2021-10', Thomas Prisner, 09 Feb 2021
  • RC3: 'Comment on mr-2021-10', Anonymous Referee #3, 10 Feb 2021

Thorsten Bahrenberg et al.

Data sets

The decay of the refocused Hahn echo in DEER experiments Bahrenberg, Thorsten, Jahn, Samuel M., Feintuch, Akiva, Stoll, Stefan, and Goldfarb, Daniella https://doi.org/10.5281/zenodo.4449018

Thorsten Bahrenberg et al.

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Short summary
DEER is a method, which provide information on the structure of proteins by attaching to the protein two spins labels at well-defined location and measuring the distance between them. The sensitivity of the method in terms of the amount of the protein that is needed for the experiment depends strongly on the relaxation properties of the spin label and the composition of the solvent. In this work we show how to set up the experiment for best sensitivity when the solvent is water, H2O.