Environmental scanning electron microscope (ESEM)
Electron microscopy supplies a technical and scientific support:
in microstructural characterization through SEM imaging in several research programs and for diagnostics in different topics on production processes and end-products expressed by manufacturing companies, which demands for non-destructive analytical techniques and functionality are increasing.
FEI Quanta 200 variable pressure-environmental/ESEM® scanning electron microscope is a high-performance thermoionic-W emission SEM column, with dual-anode source emission geometry, fixed objective aperture and through-the-lens differential pumping.
The environmental scanning electron microscope (ESEM®) technology -operating in variable pressure and even in “wet” mode- allows to examine non-conductive and high-content water samples which are not to be desiccated or coated, so that their original characteristics may be preserved for further testing or manipulation.
Quanta 200 reaches a resolution of 3.0nm @ 30kV, with a high S/N ratio both in low vacuum and environmental pressure. Accelerating voltage (200V – 30kV) and the probe current (up to 2μA) are continuously adjustable.
Samples may be analyzed and imaged in 3 modalities:
1) High vacuum (<6•10-4 Pa): for conductive/coated (Au-C) materials.
2) Low vacuum: (10÷130 Pa): allows analyses for not-dessiccated or not-conductive samples, in their original characteristics without any preparation, such as paper, polymers and resins, ceramics, fibers, textiles and substances susceptible to degas; Materials still in-process without any surface treatment, preserving their usefulness avoiding coatings to make them conductive. (e.g. gold or carbon coating/sputtering).
3) ESEM-environmental (10÷2600 Pa): to observe and imaging of high-content until water-dwelling samples. ESEM mode does not requires any preparation of samples and allows to operate in wet environment (100% H2O humidity in chamber).
The Peltier heating/cooling stage (20°-5°C lets us work with combination of low temperature and high water vapor pressure permitting to achieve 100% relative humidity at the sample surface: in these conditions moist biological materials or samples in presence of liquids (living cells, biological tissues and cultures, etc.) are not damaged by the electronic beam and may be imaged, modified and imaged again in time.
ESEM FEI Quanta 200 in ISTEC laboratories is equipped with the following facilities:
- SED Everhart-Thornley secondary electrons detector, in HV;
- LFD (large field secondary electrons detector in LV;
- GSED (gaseous secondary electrons det., in ESEM mode).
- BSED/GAD (Backscattered electrons det.-gaseous/analytical det.) in HV/LV
- GBSED (Gaseous BSE detector) in ESEM mode.
- X-rays Energy dispersive spectroscopy-EDS (NEW XL-30, EDAX GmbH) for qualitative, quantitative, mapping, spotting and areal analyses (@10mmWD take-off angle: 35°).
- BSED/CLD detector for fotocathodoluminescence electrons.
- Thermostatic Peltier heating/cooling stage (20°-5°C) (in ESEM mode) with external chiller.
- Eucentric goniometer stage with R = 360° continuous and • repeatability: 2μm
- Digital video recording (.avi)
Field of applications
Materials Science: microstructure and texture studies and imaging, on polished and fracture surfaces of ceramics, metals, glasses, polymers, composites, etc.
Studies on ceramic systems along crystallization-melting, hydration process in clay minerals, thermal effects on metals.
Chemical, mineralogical and petrographic investigations on geological and archaeological samples; analyses on samples from oil-drilling coreboring.
- Environmental sciences and hygiene: non-living chemical and physical factors in the environment, agents from pollution, both biological (bacteria and fungine pathogens, etc.) and abiotic nature (nanoparticles, fibers, pesticides, heavy metals).,
- Safety and conservation of cultural heritage in terms of mural paintings and frescoes restorations; studies on ceramics, mosaics, mortars, plasters and concrete. Surface degradation analyses (acid rains/black crusts)
- Textile industry field: for surface studies on fibers and their absorbing power;
- Biomedical field: morphological imaging, qualitative and quantitative chemistry in biological and/or inorganic materials; in pharmaceutical applications for esteems on drugs hydrosolubility.
- In cosmetics, food safety, etc. for structural and analytical investigations until nanometric scale