Transmission Electron Microscope (TEM)


Transmission Electron Microscope (TEM)

JEOL JEM-2100F with Gatan GIF-Tridiem and Oxford Inca XEDS


The JEOL JEM-2100F is a computer-controlled high-resolution transmission electron microscope (HR-TEM) with excellent analytical performance for daily use in a multi-user environment. The configuration of the instrument combines ease-of-use with capabilities for routine atomic resolution imaging of crystal lattices by coherent electron scattering or phase contrast (TEM); or by incoherent electron scattering of Z-contrast in the scanning transmission electron microscopy (STEM) mode.  It offers routinely local spatial resolution at 2nm or better for analytical TEM, i.e., analysis of elemental composition and chemistry (electronic bonding) by X-ray energy dispersive spectroscopy (XEDS), diffraction for crystal structure determination and crystallographic studies, and electron energy-loss spectroscopy (EELS). When operated in STEM mode the instrument offers electron probes as small as 0.16 nm for incoherent imaging and of 0.5 nm for analytical purposes of XEDS and EELS. The JEM-2100F is equipped with attachments for XEDS analysis from Oxfrod Instruments (Inca platform) and a GIF TRIDIEM post-column energy filter (Gatan Inc.) for acquisition of energy-filtered images and diffraction.

The JEM-2100F HR-TEM operates with a Schottky field-emission electron gun (FEG) at 120kV up to 200 kV, offers large sample tilt (≥30˚ X- & Y-tilt) combined with superior XEDS sensitivity (due to increased acceptance angle ≈0.3 sr w.r.t. standard ≈0.1sr) without significantly affecting image resolution, achieving 0.22 nm point resolution and information limit of about 0.16 nm in TEM mode. Extension of image resolution towards the information limit by exit-plane wave function reconstruction from combined beam-tilt and through focal-series is available, and is greatly aided by improved beam and stage stability. In gold (Au) test specimens, the good stability of the instrument facilitates lattice periodicity resolution to 0.102 nm on a routine basis. In TEM and STEM mode the field emission gun (FEG) produces intense electron point probes with diameters of 0.5 nm and down to 0.16 nm, respectively, carrying sufficient current to provide for local diffraction, compositional and chemical analysis with sub-nanometer resolution. Using the high-angle annular dark-field (HAADF) detector enables atomic-number sensitive incoherent (Z-contrast) imaging with atomic column resolution. The XEDS system enables detection of beryllium or heavier elements (atomic number Z≥4) and XEDS mapping of the fields of view captured in images. The post-column energy-filter is a very powerful component of the system, facilitating energy-filtered (EF) TEM and EELS. Forcing the electrons scattered by the specimen onto an energy-dispersive path and onto a CCD-camera facilitates EELS with resolution of 1.05 eV (1s acquisition, 200 kV, 180 µA emission current) and 0.63 eV (1s acquisition, 200 kV, 40 µA emission current). Use of the energy-selecting slit allows zero-loss (ZL) filtering for imaging and diffraction with only elastically scattered electrons, which increases contrast in phase contrast (HREM) and diffraction contrast images, and facilitates use of thicker specimens and quantitative electron diffraction (QED), especially useful in combination with convergent beam ED (CBED). Electron spectroscopic imaging (ESI) in TEM mode is accomplished by use of the energy-selecting slit to form images of element specific energy-loss and enables rapid elemental mapping directly in the EF-TEM images, which has great advantages over XEDS mapping w.r.t. speed of acquisition. Finally, the instrument can be operated remotely via the university network, which further improves beam and sample stage stability, ready incorporation into teaching and outreach activities, and minimizes potential of physical damage due to user error. This combination of capabilities supports research needs in the physical sciences and engineering at the University of Pittsburgh and is a regional resource available to non-Pitt users via collaborative efforts.

User Manual