Adiabatic Spin Dynamics by Chirped Microwave Pulses Based on AWG-ESR

We present methods for optimizing frequency sweeps for “fast” adiabatic inversion in ESR spectroscopy. To perform the sought optimization, we need to either exploit “constant adiabaticity” chirps or utilize the gradient ascent pulse engineering (GRAPE) method: in these ways, the Δ(t) profiles are evaluated, which allow one to minimize the duration of the chirps. Arbitrary waveform generator-based ESR (AWG-ESR) enables us to apply versatile MW-shaped pulses and to control dynamics of the spin systems under study. Spin dynamics for spin inversion by the shaped pulses were observed. Comparison of different frequency sweeps applied to both a homogeneous ESR signal and a spin packet of inhomogeneously broadened ESR signals indicates that the duration of the adiabatic sweeps can be significantly reduced.