This paper reports a systematic study of the collection efficiency of an X-ray energy dispersive spectrometer (EDS) equipped on a newly installed 200 kV TEM/STEM. Understanding of the collection efficiency is critical to quantitative compositional measurements, and several factors affect the overall collection efficiency. Solid angle is arguably the most important parameter, which describes the angular extent of X-rays emitted by a point source and collected by the detector system [1][2]. Once a particular EDS system is installed on a specific TEM, the solid angle remains a constant. However, there are several variables that affect the performance, such as the specimen holder penumbra (shadowing), specimen eucentric height, probe current, accelerating voltage, and number and location of the detectors used (in the case of multiple-detector configuration).Herein, we evaluate the collection efficiency of the twin Oxford X-Max 100TLE EDS system on the probe-corrected Hitachi HF5000 TEM/STEM at the University of Arizona. Shown in Figure 1, two rectangular-shaped 100 mm 2 window-less X-Max 100TLE detectors are oriented normal to the axis of the specimen holder, 180 o apart. Following Zaluzec formula [2], the solid angle of each detector is calculated to be 0.85 sr, providing a total angle of 1.70 sr for the twin configuration. We measured the penumbra of the Gatan 646 double-tilt low-background (Be) holder using the EDS "Test specimen" recommended by Zaluzec [3]. The Test Specimen is a 20 nm Ge/20 nm SiN/20 nm thick membrane (500 µm x 500 µm) with arrays of 2 µm-diameter holes on a Si wafer (TEMwindows/SiMPore Inc.) [3]. With the known thickness, using N K, Si K, Ge K and L peaks, this specimen can be used to calibrate the energy resolution over a wide range. It can also be used to monitor the possible deterioration due to detector contamination over time. We undertook all the measurements at 200 kV at a probe current of 1.40 nA unless otherwise stated. Fig. 2 plots the Ge Kα peak intensity as a function of the α-tilt from -10° to +10° while using Detector 1 alone (positive tilt is in the clockwise direction towards Detector 1) and in twin configuration. It shows that using only Detector 1, the penumbra decreased linearly with increasing α-tilt. The counts almost doubled when tilted from -10 to +10 °. However, the penumbra profile in the twin-detector setting is much flatter throughout out the range, with less than 10% intensity variation. We are going to further investigate the penumbra in the single and twin-configuration as a function of the full α and β tilt range. We also acquired EDS measurements at various probe currents. Fig. 3 presents the Ge Kα peak intensity as a function of the probe current. The X-ray counts increased linearly with the probe current except the first data point. We will repeat the experiment and verify whether it was a measuring error. In summary, the findings from this study will enable us to optimize the experimental setup for quantitative X-ray analysis at its maximal collection efficie...

Observation of reaction processes in the in-situ environment has been increasingly demanded to understand the properties of catalysts and fuel cells with a transmission electron microscope (TEM). Insitu TEM / STEM play an important role to analyze the structural changes at the atomic scale under the heating and gas environments. Furthermore, with the size shrinkage of the target materials or devices, in-situ real time imaging with a sub-Angstrom resolution has become more demanded. The analytical 200 kV cold field emission (CFE) TEM HF5000 (Hitachi High-Technologies) equipped with an inhouse designed probe-forming aberration corrector was introduced and the imaging performance of the environmental real time scanning transmission electron microscopy (STEM) was reported [1][2]. The HF5000 key feature of in-situ STEM is a live scanning acquisition (25 frames/sec) that allows real-time observation and video recording of dynamic atomic scale reactions. HF5000 provides clear real time imaging for such as structure change and elemental diffusion processes during reaction. Besides DF / BF live images, a secondary electron image in the atomic scale can be simultaneously acquired with the rich high resolution surface morphology information in-situ.

High-resolution transmission electron microscopy (HRTEM) can provide valuable insights into characterizing the underlying structure-property relations of various materials. It has been extensively applied in the detailed analysis of 2D and 3D carbon-based materials, e.g., fullerenes [1], nanotubes [2], and graphene [3,4]. We are particularly interested in Buckminster fullerene, C60, because of its recent detection in protoplanetary nebulae [5,6], its potential to contain heteroatoms [7], and its ability to selfassemble into crystalline rods, tubes and islands in meso-and nano-scales [8]. However, nanoscale analysis of such C materials requires low-voltage techniques in order to mitigate electron-beam induced damage. Here we examine C60, synthesized via aqueous self-assembly methods, as a means to investigate the low-voltage capabilities of the newly installed probe-aberration-corrected Hitachi HF5000 at the University of Arizona.The C60 nanocrystals were prepared by the wet chemistry method described in [4]. C60 crystals, suspended in isopropyl alcohol (IPA), were dropcast onto a continuous carbon film supported on 400 mesh Cu grid and left in ambient air for three weeks so that the IPA could completely evaporate. The microanalysis was carried out using a Hitachi HF5000 TEM/scanning TEM (S/TEM) equipped with Oxford twin energy-dispersive spectrometers (EDS), providing a solid angle of ~1.7 sr. The HF5000 is also equipped with a Hitachi 3 rd -order probe-aberration corrector for atomic-resolution imaging in STEM mode as well as a secondary electron detector. We performed simultaneous ADF/BF/SE imaging at 60 kV, below the knock-on damage threshold for C, and which provided atomic-scale information of the C60 crystals.Low-magnification TEM images show the facets of the C60 crystals (Fig. 1A). Bright-field STEM shows lattice fringes with a spacing of 0.81 nm, consistent with the d111 in FCC fullerenes (Fig. 1B, Fig 2A). The low contrast in the ADF indicates that the particles have similar composition to the supporting matrix and also suggests that the sample is made up of a low-Z element (Fig. 2). EDS mapping, performed using a low background (Be) holder, reveals that the crystals consists purely of C (Fig. 3A). In addition to the carbon signal, a small amount of O was also detected on the carbon support matrix (Fig. 3B). These preliminary studies indicate that the C60 crystals can be studied without noticeable beam damage at 60 kV acceleration voltage. It also paves the way to carry out EELS measurements of the plasmon excitation and fine structure of the * and * bonding of the C60 structures in various states. Furthermore, because crystal morphology is dependent on the growth substrate and solvent used [8,9], we plan on carrying out a systematic study of C60 structures that can be synthesized based on the choice of the solvent(s) in conjunction with the substrate(s) [10].

Materials research and student training at large "super-land-grant" universities like the University of Arizona (UA) require routine access to state-of-the-art instrumentation that combines 2D-and 3D-analysis of composition and structure from cm to atomic length scales. Information on the relationship between structure and property is critical to establish the feedback loop between materials characterization, growth, and optimization. The diverse materials-research programs at UA span the sciences and engineering and such programs require a range of spatially resolved analytical tools. Here we describe a core facility for electron and ion microscopy at UA, newly constructed to support these diverse research programs, and provide students, postdocs, and faculty access to state-of-the-art instrumentation and training.The facility is located in the sub-basement of the Gerard P. Kuiper building for Space Sciences, which was constructed in 1966 with funds provided by NASA. Located approximately 30 ft. below ground and slab-on-grade, the basement was renovated and repurposed to house electron and ion microscopes. The Kuiper Core Imaging Facility serves the entire UA community, including regional private-and publicsector users. It is centrally supported by the UA office of Research, Discovery, and Innovation (RDI), as part of an expanding Core Facility program. Professional scientists staff the facility, manage daily operations, train users, and a faculty user committee provides oversight and scientific direction.The facility consists of parallel instrument bays and includes space for sample preparation, meeting and workshops, and offices for laboratory scientists and visitors (Fig. 1a). A utility corridor was constructed behind several labs to house service equipment for the instruments.The Scanning Electron Microscope (SEM) suite currently houses two microscopes with room for a third instrument. The Hitachi S-4800 cold-field emission gun (cold FEG) can operate between 0.5 keV and 30 keV. It is equipped with a Thermo-Noran Si(Li) energy dispersive X-ray spectrometer (EDS) running Noran SystemSix (NSS) software. The Hitachi S-3400 is a W thermal emitter with a variable-pressure chamber and Renishaw InVia Raman system with the Structural and Chemical Analyser (SCA) interface and Reflex microscope. It is equipped with secondary-electron and backscattered-electron detectors and a Thermo-Noran SDD EDS system operating NSS software. The SEM suite also has laboratory benchtop space for sample-preparation and includes a chemical fume hood. See Fig. 1b-d.

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