Faculty Collaboration Database

Moving difference (MDIFF) non-adiabatic rapid sweep (NARS) EPR of copper(II). J Magn Reson 2013 Nov;236:15-25

Date

09/17/2013

Pubmed ID

24036469

Pubmed Central ID

PMC3919454

DOI

10.1016/j.jmr.2013.08.004

Scopus ID

2-s2.0-84883629656 (requires institutional sign-in at Scopus site)   17 Citations

Abstract

Non-adiabatic rapid sweep (NARS) EPR spectroscopy has been introduced for application to nitroxide-labeled biological samples (Kittell et al., 2011). Displays are pure absorption, and are built up by acquiring data in spectral segments that are concatenated. In this paper we extend the method to frozen solutions of copper-imidazole, a square planar copper complex with four in-plane nitrogen ligands. Pure absorption spectra are created from concatenation of 170 5-gauss segments spanning 850 G at 1.9 GHz. These spectra, however, are not directly useful since nitrogen superhyperfine couplings are barely visible. Application of the moving difference (MDIFF) algorithm to the digitized NARS pure absorption spectrum is used to produce spectra that are analogous to the first harmonic EPR. The signal intensity is about four times higher than when using conventional 100 kHz field modulation, depending on line shape. MDIFF not only filters the spectrum, but also the noise, resulting in further improvement of the SNR for the same signal acquisition time. The MDIFF amplitude can be optimized retrospectively, different spectral regions can be examined at different amplitudes, and an amplitude can be used that is substantially greater than the upper limit of the field modulation amplitude of a conventional EPR spectrometer, which improves the signal-to-noise ratio of broad lines.

Author List

Hyde JS, Bennett B, Kittell AW, Kowalski JM, Sidabras JW

Authors

Brian Bennett D.Phil. Professor and Chair in the Physics department at Marquette University
Jason W. Sidabras PhD Assistant Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Absorption
Algorithms
Copper
Copper Radioisotopes
Electromagnetic Fields
Electron Spin Resonance Spectroscopy
Fourier Analysis
Imidazoles
Ligands
Microwaves
Nitrogen Oxides
Nonlinear Dynamics
Signal Processing, Computer-Assisted
Signal-To-Noise Ratio