Kaminker Ilia, Barnes Ryan, Han Songi
Department of Chemistry and Biochemistry, University of California Santa Barbara, CA, 93106, United States.
Department of Chemistry and Biochemistry, University of California Santa Barbara, CA, 93106, United States; Department of Chemical Engineering, University of California Santa Barbara, CA, 93106, United States.
J Magn Reson. 2017 Jun;279:81-90. doi: 10.1016/j.jmr.2017.04.016. Epub 2017 Apr 27.
We report here on the implementation of arbitrary waveform generation (AWG) capabilities at ∼200GHz into an Electron Paramagnetic Resonance (EPR) and Dynamic Nuclear Polarization (DNP) instrument platform operating at 7T. This is achieved with the integration of a 1GHz, 2 channel, digital to analog converter (DAC) board that enables the generation of coherent arbitrary waveforms at K-band frequencies with 1ns 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 200GHz with >150mW power. We find that the non-linearity of the AMC poses significant difficulties in generating amplitude-modulated pulses at 200GHz. We demonstrate that in the power-limited regime of ω<1MHz phase-modulated pulses were sufficient to achieve significant improvements in broadband (>10MHz) 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 200GHz.
我们在此报告在一台运行于7T的电子顺磁共振（EPR）和动态核极化（DNP）仪器平台上实现约200GHz的任意波形生成（AWG）功能的情况。这是通过将一块1GHz、2通道的数模转换器（DAC）板集成到固态放大器倍频链（AMC）的现有架构中来实现的，该DAC板能够以1ns的分辨率在K波段频率生成相干任意波形。这使得能够在200GHz生成功率大于150mW的任意相位和幅度调制波形。我们发现，AMC的非线性在200GHz生成幅度调制脉冲时带来了重大困难。我们证明，在ω<1MHz的功率受限 regime中，相位调制脉冲足以在非相干（反转）以及相干（回波形成）实验中实现宽带（>10MHz）自旋操控的显著改善。亮点包括与传统矩形脉冲相比，反转带宽提高了一个数量级，以及在200GHz时重聚焦回波强度提高了两倍。
