Acquisition of a Field Emission Scanning Electron Microscope for Nano- to Microscale Imaging and Chemical Analysis in the College of Engineering, University of Delaware

场发射扫描电子显微镜（FESEM）是寻求工程（COE）的特拉华州大学学院电子显微镜中心，以满足立即，广泛的需要纳米分辨率扫描电子显微镜。 场发射扫描电子显微镜已成为进行微纳米形态材料成像和化学成像/分析不可或缺的仪器。 重要的是，真正的纳米级数据可以从一系列巨大的材料中获得，从导电和绝缘的“硬”无机物到“软”聚合物和生物材料。 与传统电子扫描电镜相比，（目前，工程学院（COE）EM设施中唯一运行的SEM），场发射扫描电镜提供了更高的上级分辨率（纳米结构直径小至1 nm，而我们传统的SEM分辨率在~100 nm的范围内），并且可以在低至0.5kV的电压下操作（传统的热源内部SEM必须在~ 30 kV下操作以达到~ 0.1mm的最终分辨率）。 重要的是要强调，这种低加速电压允许对COE和整个大学目前正在研究的所有材料进行直接的纳米级成像和元素分析。 在目前的COE SEM仪器JEOL JXA-840上，成像和化学分析仅限于导电无机物，并且仅在相对较低的分辨率下可行（二次电子成像为0.1 mm，X射线分析为~1.0 mm）。 聚合物和其他绝缘材料必须涂覆一层厚（约10纳米）的导电金属层，以实现可行的成像，从而完全掩盖真实的表面结构和化学性质。 由于高真空条件，在传统的SEM中，在环境条件下，具有一定水平水合的生物材料是根本不可能的。 所寻求的FESEM系统配备了最先进的能量色散X射线光谱和低温转移和冷台，用于原位水合（玻璃化）生物材料的成像。 随着当前研究范式对纳米技术的高度重视，当然在UD，这种新的FESEM将填补工程学院研究能力中的一个巨大的材料表征空白。 因此，估计超过18名教师和30至40名研究生将立即从FESEM的收购中受益。研究生和高级本科生的教育培训机会对大学整体来说是一个明显的好处。目前，我们的电子显微镜设施为大约30名学生和博士后提供服务，主要用于TEM研究目的。此外，超过25名来自工程和校园内其他自然科学专业的学生使用该设施进行课程工作（新的TEM课程MSEG/CHEG 832和MSEG 602中的TEM实验室模块，材料科学与工程提供的材料结构实验室）。 具体而言，PI将开发一个新的MSEG 602实验室模块，用于对即将入学的工程学院研究生进行具体的FESEM介绍和指导。 FESEM的增加将为不同层次和不同背景的学生提供一个独特的机会，让他们在一个跨学科的先进实验室环境中工作，这是工程电子显微镜中心的学院。 自2001年夏天以来，我们已经利用我们的JEOL FastTEM系统，包含在FEG 2010 TEM显微镜，以加强我们的本科生和研究生课堂教学和培训。FastTEM是一个与我们的场发射透射电子显微镜（FE-TEM）集成的系统，能够通过计算机网络进行远程通信和远程操作。 除了远程演示外，中小学生还经常访问实验室进行电子显微镜的内部演示。 很明显，这些内部和外部的演示激发了学生对科学和技术的好奇心和兴趣。 为了更好地实现我们的教育推广目标（并吸引高质量的本科生到大学），我们希望我们也可以用FESEM展示现代工程材料的纳米结构。 经验告诉我们，FESEM的3维形态图像比更难以解释的2维TEM数据更吸引K-12学生。 此外，UD工程学院的电子显微镜设备通过探索频道在2001年秋季的访问而在大众媒体中得到了突出报道。 观察到兴登堡金属缆绳断裂表面的微观细节，表明灾难性拉伸失效的性质。 这种受欢迎的媒体宣传也将在未来进一步追求，在此期间，我们可以突出工程学院电子显微镜设备的新实验能力。

A field emission scanning electron microscope (FESEM) is sought for the University of Delaware College of Engineering (COE) electron microscopy center to fill an immediate, widespread need for nanometer resolution scanning electron microscopy. FESEM has become an indispensable instrument in conducting micro- to nanomorphological material imaging and chemical imaging/analysis. Importantly, true nanoscale data is obtainable from of an immense array of materials, spanning "hard" inorganics, both electrically conductive and insulative, to "soft" polymeric and biologicals. In comparison to traditional thermionic SEM (currenlty, the only functioning SEM in the college of engineering (COE) EM facility), the FESEM provides far superior resolution (nanostructures as small as 1 nm in diameter while our traditional SEM resolution is in the range of ~100 of nm) and can be operated at voltages as low as 0.5kV (the traditional thermal source in-house SEM must operate at ~30kV to reach its ultimate resolution of ~0.1 mm). It is important to stress that this low accelerating voltage allows direct nanoscopic imaging and elemental analysis of all materials currently being studied in COE and across the university. On the current COE SEM instrument, a JEOL JXA-840, imaging and chemical analysis is limited to conductive inorganics and only feasible at relatively low resolution (0.1 mm for secondary electron imaging and ~1.0 mm for x-ray analysis). Polymeric and other insulating materials must be coated by a thick (~10's of nm) layer of conductive metal for feasible imaging which, consequently, completely masks true surface structure and chemistry. Biological materials with some level of hydration are simply not possible at ambient conditions in the traditional SEM due to high vacuum conditions. The sought FESEM system is equipped with state-of-the-art energy dispersive x-ray spectroscopy and a cryogenic transfer and cold stage for imaging of in situ, hydrated (vitrified) biological materials. With the large emphasis on nanotechnology in the current research paradigm, and certainly here at UD, this new FESEM will fill a large materials characterization gap in the college of engineering's research capabilities. Consequently, it is estimated that over 18 faculty members and 30 to 40 graduate students will immediately benefit in their research from the acquisition of the FESEM.Educational training opportunities for graduate students and advanced undergraduates represent a clear benefit to the university as a whole. At present, our electron microscopy facility serves about 30 students and post doctors for predominantly TEM research purposes. In addition, over 25 students from engineering and other natural science majors on campus use the facility for their course work (the new TEM course MSEG/CHEG 832 and the TEM lab module in MSEG602, Structure of Materials lab offered through Materials Science and Engineering). Specifically, a new MSEG602 lab module will be developed by the PI for specific FESEM introduction and instruction to incoming college of engineering graduate students. The addition of an FESEM will provide a unique opportunity for students at various levels and from various backgrounds to work in an interdisciplinary, advanced laboratory setting that is the College of Engineering electron microscopy center. Since the summer of 2001, we have utilized our JEOL FasTEM system, contained in the FEG2010 TEM microscope, to enhance our undergraduate and graduate classroom teaching and training. The FasTEM is a system integrated with our field emission transmission electron microscope (FE-TEM) that is capable of telecommunication and remote operation through computer networks. In addition to remote demonstrations, elementary and middle school students frequently visit the lab for in-house demonstrations of electron microscopy. It is obvious that these in-house and outside demonstrations generate significant student curiosity and interest in science and technology. To better achieve our educational outreach goals (and attract top quality undergraduates to the university) it is our desire that we also can demonstrate the nanostructures of modern engineered materials with an FESEM. Experience tells us that the 3-dimentional morphological images of the FESEM appeal more to K-12 students than 2-dimensional TEM data which is more difficult to interpret. Furthermore, the UD college of engineering electron microscopy facility has been highlighted in the popular media through a visit by the Discovery Channel in the fall of 2001. Microscopic details of fracture surfaces from metal cables of the Hindenberg were observed indicating the nature of catastrophic tensile failure. This type of popular media outreach will also be further pursued in the future during which we can highlight the new experimental capabilities of the college of engineering electron microscopy facility.