PULSED ESR MICROSCOPE

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 该子项目涉及开发和建造以脉冲模式运行的ESR显微镜。 ESR显微镜在概念上类似于众所周知的磁共振成像（MRI）系统。 主要区别在于用于测量的自旋类型（MRI中的电子与质子）和图像分辨率（微米与毫米）。 因此，大多数生物相关的样品必须掺杂或标记稳定的自由基，以促进ESR测量（类似于光学显微镜中的染料）。 此外，样品的典型尺寸必须不超过1-2 mm。当与光学显微镜结合时，脉冲ESR显微镜可以成为生物科学中有价值的工具。 空间分辨的参数，如扩散张量，O2浓度，弛豫时间（T1，T2），和ESR线形可以揭示丰富的信息，在模型和活的系统，无法通过光学方法。 在过去，已经尝试将联合收割机NMR和光学显微镜相结合，但是由于NMR的有限分辨率（~10微米）和其高成本而具有有限的成功。 ESR显微镜，这是更敏感，应该实现磁共振图像的分辨率与光学方法（~ 1微米），并在更低的成本（简单的电磁体与大型超导磁NMR显微镜）。我们已经构建了一个脉冲ESR显微镜的初始原型。 该系统由自制的6-17 GHz脉冲微波电桥、脉冲梯度驱动器、用于系统控制和数据采集的计算机以及脉冲成像探头（谐振器+梯度线圈）组成。 在16 GHz下展示了分辨率为3x 3x 8微米的三维ESR图像。 进一步发展到更高的频率9高达~60 GHz，将有助于所需的亚微米图像分辨率。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This subproject involves the development and construction of an ESR microscope operating at pulsed mode. The ESR microscope is conceptually similar to the well known Magnetic Resonance Imaging (MRI) system. The main differences are with the type of spins used for the measurements (electron vs. protons in MRI), and the image resolution (microns vs. mm). Consequently, most biologically-related samples must be doped or labelled with stable radicals to facilitate the ESR measurement (similar to dyes in optical microscopy). Furthermore, the samples must be with a typical size of no more than 1-2 mm. When combined with optical microscopy, the pulsed ESR microscope can be a valuable tool in bio-science. Spatially resolved parameters such as diffusion tensor, O2 concentration, relaxation times (T1, T2), and the ESR lineshape can reveal a wealth of information in model and live systems, inaccessible by optical methods. In the past attempts has been made to combine NMR and optical microscopy, but with limited success due to the limited resolution of NMR (~10 microns) and its high cost. The ESR microscope, which is much more sensitive, should achieve magnetic resonance images with resolution comparable to optical method (~ 1 micron), and at much lower cost (simple electromagnet vs. large superconducting magnetic in NMR microscopy).We have constructed an initial prototype of the pulsed ESR microscope. The system is made of a home-built 6-17 GHz pulsed microwave bridge, a pulsed gradient driver, a computer for system control and data acquisition, and a pulsed imaging probe (resonator+ gradient coils). Three dimensional ESR images with a resolution of 3x3x8 microns were demonstrated at 16 GHz. Further progress to higher frequencies 9up to ~60 GHz, would facilitate the required sub-micron image resolution.