MRI: Acquisition of a Scanning XPS Microprobe

技术摘要凯斯西储大学的世伟洛克材料表面分析中心请求NSF资助一套最先进的XPS系统（X射线光电子能谱仪，也称为ESCA）。XPS是多用户中心中使用最广泛的技术，每年有100多名学术用户使用XPS，占仪器使用量的20%。然而，现有的XPS系统是该中心所有仪器中最古老的（已有20年历史！）缺乏重要的能力。我们提出的替代产品PHI 5000 VersaProbe将XPS技术提升到了一个新的水平。它可以将分析X射线聚焦到直径小于10 μ m的高强度局部探头上，并在样品表面上进行光栅扫描。结合XPS探测表面以下的浅深度，这将使得能够对非常小体积的材料进行局部化学分析和具有高横向分辨率的元素绘图。该仪器配备了一个电子能量分析仪，优化了能量分辨率和高角度接受。这将使高性能的微面积光谱，高灵敏度的大面积光谱，二次电子成像，和高性能溅射深度剖析。此外，拟议的仪器包括一个系统的手小康电荷中和，这将大大有利于非导电样品的分析。这些能力是非常需要的中心的用户，并将使重大进展，在许多领域的材料研究，包括发展（i）一种新的气相渗碳工艺，使表面的结构合金（例如不锈钢）通过引入间隙溶质的“巨大”过饱和而变得超硬且更耐腐蚀，（ii）用于更便宜和更有效的基于PEM的燃料电池的新型催化剂纳米颗粒，（iii）用于生物医学应用的基于金刚石的电极，以及（iv）用于神经记录和刺激传感器的基于微制造的柔性电极阵列平台技术。与其广泛的应用相对应，非技术摘要凯斯西储大学世伟洛克材料表面分析中心请求美国国家科学基金会（NSF）资助一种用于分析表面和近表面区域化学成分的最先进仪器--最上面的2到3层原子-由不同的材料组成。由于表面是材料与其环境相互作用的地方，因此这种能力对于开发具有上级性能的新材料至关重要。表面分析的一种成熟且非常强大的方法是“X射线光电子能谱法”：在真空中用软的低能量X射线照射材料表面，使表面正下方的前几层原子释放电子（“光电效应”），通过测量这些带电粒子的能量，可以确定发射它们的原子的化学身份。毫不奇怪，X射线光电子能谱法是世伟洛克中心最广泛使用的技术。然而，可用的系统是该中心最古老的仪器（已有20年历史！）缺乏重要的能力。我们提出的替代方案将技术提升到了一个新的水平。最重要的是，它可以将分析X射线聚焦到一个小点上，并在样品表面上移动。结合X射线光电子能谱法探测材料的浅深度，可以对非常小体积的材料进行局部化学分析，并以高精度绘制整个样品表面的化学成分变化。此外，所提出的仪器可以有效地分析在相当深的表面以下的组合物，通过连续地从一个小的表面区域去除材料的薄层，并分析新暴露的材料的表面组成。这些能力是每年使用世伟洛克中心的100多名材料研究人员中的许多人的需求。新仪器将使材料研究的许多重要领域取得进展，包括（i）开发一种使合金表面（例如不锈钢）超硬且更耐腐蚀，通过延长许多技术应用中的金属部件的寿命来提供巨大的节能，（ii）新型催化剂纳米颗粒，用于成本更低、效率更高的便携式燃料电池-将燃料中所含的化学能转化的装置（iii）用于各种生物医学应用的新型金刚石电极，以及（iv）用于将神经与电子设备接触的新型微电极阵列。与其广泛的应用相对应，新仪器将在凯斯研究生和博士后研究人员的教育和培训中发挥重要作用。

Technical AbstractThe Swagelok Center for Surface Analysis of Materials at Case Western Reserve University requests NSF funds for a state-of-the-art XPS system (X-ray photoelectron spectrometry, also known as ESCA). XPS is the most intensively employed technique in the multi-user center, accounting for 20% of instrument use by more than 100 academic users each year. However, the available XPS system is the oldest of all instruments in the center (it is 20 years old!) and lacks important capabilities. The replacement we propose, the PHI 5000 VersaProbe, takes the technique of XPS to the next level. It can focus the analyzing X-rays to a highly intense local probe with a diameter less than 10 um and raster it over the specimen surface. Combined with the shallow depth to which XPS probes below the surface, this will enable local chemical analysis of very small volumes of material and elemental mapping with high lateral resolution. The instrument is equipped with an electron energy analyzer optimized for energy resolution and high-angle acceptance. This will enable high-performance micro-area spectroscopy, high-sensitivity large-area spectroscopy, secondary electron imaging, and high-performance sputter depth profiling. In addition, the proposed instrument includes a system for hands-off charge neutralization, which will greatly facilitate the analysis of non-conducting specimens. These capabilities are much in demand by the center's users and will enable major advances in many areas of materials research, including the development of (i) a novel gas-phase carburization process that makes the surfaces of structural alloys (e.g. stainless steel) ultra-hard and much more corrosion-resistant by introducing a "colossal" supersaturation of interstitial solutes, (ii) novel catalyst nanoparticles for less expensive and more efficient PEM-based fuel cells, (iii) diamond-based electrodes for biomedical applications, and (iv) a micro-fabrication-based, flexible electrode-array platform technology for neural recording and stimulation sensors. Corresponding to its broad range of applications, the new instrument will play an important role in the education and training of graduate students and postdoctoral researchers at Case.Non-Technical AbstractThe Swagelok Center for Surface Analysis of Materials at Case Western Reserve University requests NSF funds for a state-of-the-art instrument for analyzing the chemical composition of the surface and near-surface regions - the topmost 2 to 3 layers of atoms - of diverse materials. Inasmuch as the surface is where materials interact with their environment, this capability is of central importance for developing new materials with superior properties. A well-established and very powerful method for surface analysis is "X-ray photoelectron spectrometry": Irradiating the surface of the material with soft, low-energy X-rays in vacuum causes atoms in the first few layers directly below the surface to give off electrons (the "photoelectric effect"), and by measuring the energy of these charged particles, the chemical identity of the atoms that emitted them can be determined. Not surprisingly, X-ray photoelectron spectrometry is the most intensively employed technique in the Swagelok Center. However, the available system is the oldest instrument in the center (it is 20 years old!) and lacks important capabilities. The replacement we propose takes the technique to the next level. Most importantly, it can focus the analyzing X-rays to a small spot and move it across the specimen surface. Combined with the shallow depth to which X-ray photoelectron spectrometry probes the material, local chemical analysis of very small volumes of material will be possible, as well as mapping variations in chemical composition across the specimen surface with high accuracy. Moreover, the proposed instrument can efficiently analyze the composition at considerable depths below the surface by successively removing thin layers of material from a small surface region and analyzing the surface composition of the freshly exposed material. These abilities are much in demand by many of the more than 100 materials researchers using the Swagelok Center each year. The new instrument will enable progress in many important areas of materials research, including the development of (i) a novel process that makes the surface of alloys (e.g. stainless steel) ultra-hard and much more corrosion-resistant, providing tremendous energy-savings by extending the lifetime of metal parts in many technical applications, (ii) novel catalyst nanoparticles for less expensive and more efficient portable fuel cells - devices that convert the chemical energy contained in a fuel (e.g. alcohol) directly to electricity, (iii) novel diamond electrodes for diverse biomedical applications, and (iv) novel microelectrode arrays for contacting nerves to electronic devices. Corresponding to its broad range of applications, the new instrument will play an important role in the education and training of graduate students and postdoctoral researchers at Case.