J Magn Reson 2019 Jun 11;303:42-47. Epub 2019 Apr 11.
Quantronics Group, SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191, Gif-sur-Yvette Cedex, France. Electronic address:
In high sensitivity inductive electron spin resonance spectroscopy, superconducting microwave resonators with large quality factors are employed. While they enhance the sensitivity, they also distort considerably the shape of the applied rectangular microwave control pulses, which limits the degree of control over the spin ensemble. Here, we employ shaped microwave pulses compensating the signal distortion to drive the spins faster than the resonator bandwidth. This translates into a shorter echo, with enhanced signal-to-noise ratio. The shaped pulses are also useful to minimize the dead-time of our spectrometer, which allows to reduce the wait time between successive drive pulses.