We investigate a new time domain approach to dynamic nuclear polarization (DNP), the frequency-swept integrated solid effect (FS-ISE), utilizing a high power, broadband 94 GHz (3.35 T) pulse EPR spectrometer. The bandwidth of the spectrometer enabled measurement of the DNP Zeeman frequency/field profile that revealed two dominant polarization mechanisms, the expected ISE, and a recently observed mechanism, the stretched solid effect (S²E). At 94 GHz, despite the limitations in the microwave chirp pulse length (10 μs) and the repetition rate (2 kHz), we obtained signal enhancements up to ∼70 for the S²E and ∼50 for the ISE. The results successfully demonstrate the viability of the FS-ISE and S²E DNP at a frequency 10 times higher than previous studies. Our results also suggest that these approaches are candidates for implementation at higher magnetic fields.

中文翻译：

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扫频积分和拉伸固体效应动态核极化

我们使用高功率，宽带94 GHz（3.35 T）脉冲EPR光谱仪，研究了动态核极化（DNP）的新时域方法，即频扫积分固体效应（FS-ISE）。光谱仪的带宽能够测量DNP塞曼频率/场分布，揭示了两种主要的极化机制，即预期的ISE，以及最近观察到的机制，即拉伸的固体效应（S ² E）。在94 GHz下，尽管微波线性调频脉冲长度（10μs）和重复频率（2 kHz）受限制，但对于S ² E和ISE ，我们获得了高达〜70的信号增强和〜50的信号增强。结果成功证明了FS-ISE和S ²的可行性E DNP的频率比以前的研究高10倍。我们的结果还表明，这些方法是在更高磁场下实施的候选方法。