title: Digital EPR with an arbitrary waveform generator and direct detection at the carrier frequency.
abstract: A digital EPR spectrometer was constructed by replacing the traditional bridge with an arbitrary waveform generator (AWG) to produce excitation patterns and a high-speed digitizer for direct detection of the spin system response at the carrier frequency. Digital down-conversion produced baseband signals in quadrature with very precise orthogonality. Real-time resonator tuning was performed by monitoring the Fourier transforms of signals reflected from the resonator during frequency sweeps generated by the AWG. The capabilities of the system were demonstrated by rapid magnetic field scans at 256 MHz carrier frequency, and FID and spin echo experiments at 1 and 10 GHz carrier frequencies. For the rapid scan experiments the leakage through a cross-loop resonator was compensated by adjusting the amplitude and phase of a sinusoid at the carrier frequency that was generated with another AWG channel.
authors.affiliation: Department of Chemistry and Biochemistry, School of Engineering and Computer Science, University of Denver, Denver, CO 80208, United States.
authors.forename: Mark
authors.initials: M
authors.lastname: Tseitlin
authors.forename: Richard W
authors.initials: RW
authors.lastname: Quine
authors.forename: George A
authors.initials: GA
authors.lastname: Rinard
authors.forename: Sandra S
authors.initials: SS
authors.lastname: Eaton
authors.forename: Gareth R
authors.initials: GR
authors.lastname: Eaton
mesh_terms: D000465:Algorithms; D003627:Data Interpretation, Statistical; D004574:Electromagnetic Fields; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D005583:Fourier Analysis; D007202:Indicators and Reagents; D012815:Signal Processing, Computer-Assisted
chemical_list: D007202:Indicators and Reagents