X-Band EPR Spectrometer with Customizable Arbitrary Waveform Generator based on a 1 GHz DAC Board

We present an EPR spectrometer featuring an arbitrary waveform generator (AWG) operating at 8–10 GHz (X-band) that is based on a 1 GHz digital-to-analog converter (DAC) boardwith a 42 dB (i.e. 14-bit) dynamic range. This AWG-capable spectrometer was developedto widen the scope of pulsed electron paramagnetic resonance (EPR) and enable new experiments. It generates shaped X-band pulses with precise amplitude and phase control and can specify inter-pulse delays with a time resolution of ≤250 ps. We demonstrate the capabilities of the spectrometer by presenting spin-echo measurements that implement an entirely digitally controlled and calibrated 16-step phase cycle and by measuring the excitation profiles seen by the spins in the microwave resonator as they respond to various pulse shapes, including rectangular, triangular, Gaussian, sinc, and adiabatic rapid passage waveforms. Potential applications of these capabilities, and their implementation in commercial instrumentation, will be discussed.