A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that can be detected and that contain information about the sample's surface topography and composition. The electron beam is generally scanned in a raster scan pattern, and the beam's position is combined with the detected signal to produce an image. SEM can achieve resolution better than 1 nanometer. Specimens can be observed in high vacuum, in low vacuum, in wet conditions (in environmental SEM), and at a wide range of cryogenic or elevated temperatures. Read more
What is an Electron Microprobe, how is it different from a Scanning Electron Microscope, and when does a researcher choose the probe vs. the SEM?
An electron microprobe (or electron probe microanalyzer, EPMA) is a specialized scanning electron microscope, optimized for accurate and precise quantitative compositional analysis of solid materials at the micro-scale. In addition to electron imaging capability, it has a reflected light microscope to check focus and surface quality. It is equipped with five wavelength-dispersive X-ray spectrometers (WDS), which use diffracting crystals to separate the characteristic X-rays emiited by a sample before counting them. This gives the EPMA much finer spectral resolution than the energy-dispersive X-ray spectrometers (EDS) often installed on SEMs. In turn, in combination with careful analysis of standards and matrix correction software, WDS allows quantification of all major elements heavier than N and minor elements down in some cases to ~100 ug/g, with typically 1% relative precision and accuracy. Because each WDS spectrometer only counts one wavelength at a time, one usually only analyzes a short list of elements. By comparison, EDS analysis on the SEM achieves only about 5% relative precision and accuracy and generally cannot detect minor elements below ~1000 ug/g, but simultaneously measures all the elements. Hence, when accurate and precise determination of a known list of elements is desired, the EPMA is the instrument of choice. When quicker qualitative assessment of the elements present is desired, the SEM is the tool of choice. EPMA analysis gives a student an opportunity to learn and think about a number of important issues in microanalysis and in the science and statistics of measurement more broadly: choice of standards, background subtraction, counting statistics, reproducibility, detection limits, internal and external precision, etc.
Energy-dispersive X-ray spectroscopy (EDS, EDX, or XEDS), sometimes called energy dispersive X-ray analysis (EDXA) or energy dispersive X-ray microanalysis (EDXMA), is an analytical technique used for the elemental analysis or chemical characterization of a sample. It relies on an interaction of some source of X-ray excitation and a sample. Its characterization capabilities are due in large part to the fundamental principle that each element has a unique atomic structure allowing unique set of peaks on its X-ray emission spectrum. Read more
Atomic-force microscopy (AFM) or scanning-force microscopy (SFM) is a very high-resolution type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit. Read more
Profilometer is a measuring instrument used to measure a surface's profile, in order to quantify its roughness. Read more
Ultraviolet–visible spectroscopy or ultraviolet-visible spectrophotometry (UV-Vis or UV/Vis) refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region. This means it uses light in the visible and adjacent (near-UV and near-infrared [NIR]) ranges. The absorption or reflectance in the visible range directly affects the perceived color of the chemicals involved. Read more
Confocal microscopy is an optical imaging technique for increasing optical resolution and contrast of a micrograph by means of adding a spatial pinhole placed at the confocal plane of the lens to eliminate out-of-focus light. It enables the reconstruction of three-dimensional structures from the obtained images. Read more
The optical microscope, often referred to as light microscope, is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although there are many complex designs which aim to improve resolution and sample contrast. Read more
The molecular analyzer is used for the measurement of the size, electrophoretic mobility of proteins, zeta potential of colloids and nanoparticles, and optionally the measurement of protein mobility and microrheology of protein and polymer solutions.
Fourier transform infrared spectroscopy (FTIR) is a technique which is used to obtain an infrared spectrum of absorption or emission of a solid, liquid or gas. An FTIR spectrometer simultaneously collects high spectral resolution data over a wide spectral range. This confers a significant advantage over a dispersive spectrometer which measures intensity over a narrow range of wavelengths at a time. Read more
X-ray fluorescence (XRF) is the emission of characteristic "secondary" (or fluorescent) X-rays from a material that has been excited by bombarding with high-energy X-rays or gamma rays. The phenomenon is widely used for elemental analysis and chemical analysis, particularly in the investigation of metals, glass, ceramics and building materials, and for research in geochemistry, forensic science, archaeology and art objects such as paintings and murals. Read more
The following fabrication tools are available:
Raith Voyager Electron Beam Lithography tool
Electron Beam Deposition, Angstrom Engineering, Model 450
Reactive Ion Etching tool, NGP80, Oxford Instruments
Reactive Ion Etching tool, TRION (Norfolk State University)
FIB FEI Nova 600 Nanolab (Dual Beam) with FESEM capability (COSINC)
The above nano-scale images are captured with the same tools available for your use (for education or outreach) via our remote access service. Each RAIN partner has samples available, which vary by location. If you have any specific items that you'd like to view during your session, let us know when requesting your session and we will provide you with shipping instructions.