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向美国国家科学基金申请最先进的XPS系统（x射线光电子能谱，也称为ESCA）的资助。XPS是多用户中心使用最多的技术，每年有100多个学术用户使用的仪器占20%。然而，可用的XPS系统是中心所有仪器中最古老的（已有20年历史！）并且缺乏重要的功能。我们提出的替代品，PHI 5000 VersaProbe，将XPS技术提升到一个新的水平。它可以将分析的x射线聚焦到一个直径小于10微米的高强度局部探针上，并将其光栅覆盖在样品表面。结合XPS探测地表以下的浅层深度，这将能够对非常小体积的物质进行局部化学分析，并具有高横向分辨率的元素映射。该仪器配备了一个优化的能量分辨率和高角度接收的电子能量分析仪。这将使高性能微区光谱、高灵敏度大面积光谱、二次电子成像和高性能溅射深度分析成为可能。此外，该仪器还包括一个不干涉电荷中和系统，这将极大地促进非导电样品的分析。该中心的用户对这些能力有很大的需求，并将使材料研究的许多领域取得重大进展，包括：(1)一种新的气相渗碳工艺的发展，通过引入“巨大”过饱和的间隙溶质，使结构合金（如不锈钢）的表面变得超硬，更耐腐蚀；(2)新型催化剂纳米颗粒，用于更便宜、更高效的pem燃料电池。（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结构的柔性电极阵列平台技术。与它广泛的应用范围相对应，新仪器将在凯斯的研究生和博士后研究人员的教育和培训中发挥重要作用。凯斯西储大学的世伟洛克材料表面分析中心向美国国家科学基金申请了一种最先进的仪器，用于分析各种材料的表面和近表面区域（最上面的2到3层原子）的化学成分。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优越性能的新材料至关重要。“x射线光电子能谱法”是一种行之有效的、非常有效的表面分析方法：在真空中用软的、低能的x射线照射材料表面，使表面以下的前几层原子发出电子（“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特性。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，可用的系统是中心最老的仪器（已经20年了！），缺乏重要的功能。我们建议的替代方案将技术提升到一个新的水平。最重要的是，它可以将分析的x射线聚焦到一个小点上，并在标本表面移动。结合x射线光电子能谱探测材料的浅深度，可以对非常小体积的材料进行局部化学分析，并以高精度绘制样品表面化学成分的变化。此外，该仪器可以通过从一个小的表面区域连续去除薄层材料并分析新暴露材料的表面成分，从而有效地分析表面以下相当深度的成分。在每年使用世伟洛克中心的100多名材料研究人员中，许多人都非常需要这些能力。新仪器将使材料研究的许多重要领域取得进展，包括：(1)一种新工艺的发展，使合金（如不锈钢）的表面超硬和更耐腐蚀，通过延长金属部件在许多技术应用中的使用寿命，提供巨大的能源节约；（二）用于更便宜和更高效的便携式燃料电池的新型催化剂纳米粒子——将燃料（例如酒精）中所含的化学能直接转化为电能的装置，（三）用于各种生物医学应用的新型金刚石电极，以及（四）用于将神经与电子装置接触的新型微电极阵列。与它广泛的应用范围相对应，新仪器将在凯斯的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.