title: Broadband spin echoes and broadband SIFTER in EPR.
abstract: Applications of broadband pulses for EPR have been reported for FID, echo detection and inversion pulses recently. Here we present a broadband Hahn, stimulated and refocused echo sequence derived from adiabatic pulses. The formation of echoes is accomplished by using variable chirp rates and pulse lengths. In all three broadband echo experiments the complete spectral shape of a nitroxide (about 70 Gauss at X-band frequency) could be recovered by Fourier transformation of the quadrature detected echo signals. Such broadband echoes provide an exciting opportunity to optimize pulse sequences where a full excitation of the spectrum is mandatory for an optimum performance. We applied our pulses to the SIFTER (single frequency technique for refocusing dipolar couplings) experiment, a solid echo based pulse sequence to measure the dipolar coupling between two unpaired electron spins. By employing our broadband Hahn echo sequence on a nitroxide biradical we could achieve an artifact free dipolar evolution time trace in the SIFTER experiment with 95% modulation depth at X-band frequency and of 10% modulation depth at Q-band frequency.
authors.affiliation: Institut für physikalische und theoretische Chemie, Goethe Universität Frankfurt, Max von Laue Straße 7, 60438 Frankfurt am Main, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Schöps
authors.affiliation: Institut für physikalische und theoretische Chemie, Goethe Universität Frankfurt, Max von Laue Straße 7, 60438 Frankfurt am Main, Germany.
authors.forename: Philipp E
authors.initials: PE
authors.lastname: Spindler
authors.affiliation: Institut für physikalische und theoretische Chemie, Goethe Universität Frankfurt, Max von Laue Straße 7, 60438 Frankfurt am Main, Germany.
authors.forename: Andriy
authors.initials: A
authors.lastname: Marko
authors.affiliation: Institut für physikalische und theoretische Chemie, Goethe Universität Frankfurt, Max von Laue Straße 7, 60438 Frankfurt am Main, Germany. Electronic address: Prisner@Chemie.Uni-Frankfurt.de.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Prisner
keywords: Broadband pulses; Dipolar spectroscopy; Pulsed EPR