The Gemini 300 scanning electron microscope has a field emission source (up to 30 kV) and is equipped with an Everhart-Thornley secondary electron detector for morphological analysis and a 6-segment backscattered electron detector (BSD) for chemical contrast and TEM-like imaging. High-resolution imaging at high magnifications can be achieved using the InLens detector for secondary electrons and the Energy Selective Backscattered (EsB) detector. In addition, chemical microanalysis can be performed using the Bruker XFlahs 610M EDS probe, with a Silicon Drift Detector. The instrument is also equipped with a STEM detector to analyze TEM samples.
The Gemini instrument performs SEM analyses on various samples, from nanomaterials to dehydrated and fixed biological samples. Details of a few nanometers can be obtained. The chemical composition of samples of any nature can be investigated using backscattered electrons. The analysis requires a polished section, which must be dry and conductive.
This instrument can also perform STEM imaging of ultrathin sections or nanomaterials. The sample must be prepared for TEM analysis and placed on TEM grids. However, the STEM mode is less versatile with respect to TEM analysis. Biological sample sections can be imaged after staining with contrast agents (e.g. OsO4). TEM-like images can be also obtained working with the BSD on SEM samples.
The instrument is very versatile in terms of electron beam energy and intensity. It can be used on large samples for wide-field imaging at low magnifications and high-resolution nanoscale imaging at low energies. A huge variety of samples can be analyzed: nanomaterials, nanocomposites, fixed and dehydrated biological samples, thin sections, to name a few. The field emission source and EDS probe enable fast and accurate microanalysis in various setups, from spectra to spot, profile, and mapping analysis. The Gemini 300 SEM can be used with the Elyra 7 SIM (see optical microscope section) microscope to perform correlative optical electron microscopy and combine the fluorescence image with the scanning electron microscope image.
In the Imaging Center, different sample preparation techniques are available: critical point drying, sample coating with Gold, Chromium or Carbon (for analyses in TEM-like and backscattered mode and for EDS). Specialized personnel will help with sample manipulation and preparation before the analysis, and will advise on image analysis.
Responsible for the instrument: Dr. Davide Porrelli (MSc in Medical Biotechnologies - Nanobiotechnologies, PhD in Nanotechnology).
Availability
Location
Interdepartmental Center for Advanced Microscopy (CIMA) of the University of Trieste
Room 1, via Fleming 31/A, Trieste
Access
The instrument is available for 15 percent of machine time for ALL-MICRO network activities.
Output examples
Example on top, Imaging of cell morphology: bacteria treated with an antibacterial compound (A, courtesy of prof. Bandiera), bacteria adhered on an implant (B), osteoblasts adhered on an implant (C). Example on bottom, Thin section of a rock sample acquired with secondary (A) and backscattered (B) electrons, together with the EDS map of the main elements, merged in C (courtesy of prof. Ziberna).
