title: The use of composite pulses for improving DEER signal at 94GHz.
abstract: The sensitivity of pulsed electron paramagnetic resonance (EPR) measurements on broad-line paramagnetic centers is often limited by the available excitation bandwidth. One way to increase excitation bandwidth is through the use of chirp or composite pulses. However, performance can be limited by cavity or detection bandwidth, which in commercial systems is typically 100-200MHz. Here we demonstrate in a 94GHz spectrometer, with >800MHz system bandwidth, an increase in signal and modulation depth in a 4-pulse DEER experiment through use of composite rather than rectangular π pulses. We show that this leads to an increase in sensitivity by a factor of 3, in line with theoretical predictions, although gains are more limited in nitroxide-nitroxide DEER measurements.
authors.affiliation: SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Claire L
authors.initials: CL
authors.lastname: Motion
authors.affiliation: SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Scott L
authors.initials: SL
authors.lastname: Cassidy
authors.affiliation: SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Paul A S
authors.initials: PAS
authors.lastname: Cruickshank
authors.affiliation: SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Robert I
authors.initials: RI
authors.lastname: Hunter
authors.affiliation: SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: David R
authors.initials: DR
authors.lastname: Bolton
authors.affiliation: SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Hassane
authors.initials: H
authors.lastname: El Mkami
authors.affiliation: Department of Physics, University of Antwerp, Antwerp 2610, Belgium.
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Doorslaer
authors.affiliation: SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Lovett
authors.affiliation: SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom. Electronic address: gms@st-andrews.ac.uk.
authors.forename: Graham M
authors.initials: GM
authors.lastname: Smith
keywords: Broadband non-resonant; Composite pulses; DEER; Echo simulation; Instrumentation; PELDOR; Sensitivity enhancement; W-band