Development of AWG-driven ESR and ODMR spectrometer operated at 230 GHz

Shaped pulses have been employed in modern Electron Spin Resonance Spectroscopy (ESR) and Nuclear Magnetic Resonance Spectroscopy (NMR) at low fields. Frequency modulated pulses have been used to increase excitation bandwidth, therefore allowing broader excitation of ESR samples. Amplitude-modulated pulses allow for selective excitation which can be useful for orientation-selective studies. High magnetic field (HF) measurements also offer many advantages, including improved spectral resolution, greater sensitivity, and better spin polarization. Shaped pulses will be highly advantageous to employ in a high-frequency ESR, however it is not used because implementing them is technically challenging. For example, pulse modulation must be done prior to up-converting to higher frequencies through the frequency multiplication chain (FMC). The nonlinearity of the FMC leads to output waveforms that are significantly distorted. In this presentation, we discuss the development of a 230 GHz pulsed ESR spectrometer, driven by an arbitrary waveform generator, capable of the output of frequency-modulated and amplitude-modulated high-frequency microwaves. The capability of a shaped pulse is used for a selective excitation and efficient population inversion in high-frequency ESR and optically detected magnetic resonance (ODMR).