Arbitrary waveform modulated pulse EPR at 200 GHz

作者：Kaminker Ilia; Barnes Ryan; Han Songi^*

来源：Journal of Magnetic Resonance, 2017, 279: 81-90.

DOI：10.1016/j.jmr.2017.04.016

• DNP hardware
• High field EPR
• EPR hardware
• AWG
• Arbitrary waveform generator
• 200 GHz EPR
• Broadband pulses
• Chirp pulses
• Phase modulated pulses

We report here on the implementation of arbitrary waveform generation (AWG) capabilities at similar to 200 GHz into an Electron Paramagnetic Resonance (EPR) and Dynamic Nuclear Polarization (DNP) instrument platform operating at 7 T. This is achieved with the integration of a 1 GHz, 2 channel, digital to analog converter (DAC) board that enables the generation of coherent arbitrary waveforms at K-u-band frequencies with 1 ns resolution into an existing architecture of a solid state amplifier multiplier chain (AMC). This allows for the generation of arbitrary phase- and amplitude-modulated waveforms at 200 GHz with >150 mW power. We find that the non-linearity of the AMC poses significant difficulties in generating amplitude-modulated pulses at 200 GHz. We demonstrate that in the power-limited regime of omega(1) < 1 MHz phase-modulated pulses were sufficient to achieve significant improvements in broadband (>10 MHz) spin manipulation in incoherent (inversion), as well as coherent (echo formation) experiments. Highlights include the improvement by one order of magnitude in inversion bandwidth compared to that of conventional rectangular pulses, as well as a factor of two in improvement in the refocused echo intensity at 200 GHz.

• 出版日期2017-6