INNOVATIVE RESONATOR FOR BIOMEDICAL EPR SPECTROSCOPY

描述：研制了一种新型的EPR共振器 创新技术补助金（RR 09882）。 交叉环 谐振器（谐振器）由两个虚拟独立的集总元件组成 谐振器具有共同的样本体积，其中两个谐振器的回路 共振器正交相交。 第一谐振器激发自旋， 第二谐振器仅检测由自旋系统引起的信号。 的 源的相位噪声被反射回源， 与EPR信号隔离（70 dB）。 该传感器消除了对 在常规光谱仪中用于引导EPR的微波环行器 向探测器发出信号。 该滤波器基本上消除了源相 检测信号中的噪声，增加光谱仪灵敏度，并允许 色散光谱在相同的高信噪比（S/N）下测量， 吸收光谱 因为信号的基线是稳定的 因此，磁场调制可以用超外差代替 检测，这将不会导致信号失真（通道效应）， 场调制发生。 对于脉冲实验， 减少了仪器的死区时间， 以前无法访问的信号。 消除循环器允许 将低噪声放大器放置在样品附近并与样品沿着冷却， 大大提高了信噪比。 现在建议进一步发展生物多样性， 三种主要的方法是重要的EPR测量的生物 样品，特别是在低温下：1）表明， 超外差检测将提供失真较小的信号和较高的 信噪比（S/N）比场调制，2）表明，消除 循环器和在样品附近放置低噪声放大器将提供 最佳信噪比; 3）论证了该设计可以扩展到X波段 并结合到市售的光谱仪和低温恒温器中。

DESCRIPTION: A new type of resonator for EPR spectroscopy was developed with support of Innovative Technology Grant (RR09882). The crossed-loop resonator (CLR) consists of two, virtually-independent, lumped-element resonators that have a common sample volume where the loops of the two resonators meet orthogonally. The first resonator excites the spins, and the second resonator detects only the signal caused by the spin system. The phase noise of the source is reflected back to the source and is efficiently isolated (70 dB) from the EPR signal. The CLR eliminates the need for the microwave circulator used in conventional spectrometers to direct the EPR signal to the detector. The CLR essentially eliminates the source phase noise in the detected signal, increases spectrometer sensitivity, and allows dispersion spectra to be measured in the same high signal to noise (S/N) as absorption spectra. Because the baseline of the signal is stable with the CLR, magnetic field modulation can be replaced with superheterodyne detection, which will not cause the signal distortion (passage effects) that occur with field modulation. For pulse experiments the CLR greatly decreases the deadtime of the instrument and allows measurement of a portion of the signal previously inaccessible. Eliminating the circulator allows putting a low-noise amplifier near to, and cooled along with, the sample, greatly increasing S/N. It is now proposed to further develop the CLR in three major ways that are important for EPR measurements of biological samples, particularly at cryogenic temperatures: 1) Show that superheterodyne detection will provide a less distorted signal and higher signal-to-noise (S/N) than field modulation, 2) Show that eliminating the circulator and putting a low-noise amplifier near the sample will provide optimum S/N, and 3) Demonstrate that the design can be extended to X-band and incorporated into commercially available spectrometers and cryostats.