Resources

About 70 different chemical elements can be quantitatively determined using the Atomic Absorption Spectrometer (AAS). The AAS very accurately measures the absorption of a specific wavelength of light by atoms that have been converted to the gaseous state with either a 2300º C acetylene flame, or utilizing a temperature step program and a graphite tube. Most recently the AAS has been used to measure the amount of common metals in water, lead in river sediments and local house paint, and iron in alpine soils.

With the Agilent 5420 atomic force microscope one can image atoms on highly ordered pyrolytic graphite, as well as DNA, proteins, and a large variety of biological and chemical samples. Surface topography in 3-D can be imaged for all sorts of material science applications as well. One research group at the College is studying polymers with the AFM.

The instrument can be used as a very high resolution scanning probe microscope, or in the scanning tunneling mode to view atomic structure. Students use them for thesis work as well as in labs for chemistry and physics.

The MALDI allows for very high resolution mass analysis of samples. The MALDI can analyze very large molecules up to several hundred thousand Daltons. In the instrument, molecules are ionized using a combination of a high powered laser and a matrix molecule. The charged particles are accelerated toward a detector in an electrostatic field. The mass is measured by the length of time needed for a molecule to arrive at the detector approximately 1 meter away. This instrument is most commonly used to identify proteins based on their characteristic digestion “fingerprint”.

The Nikon High Definition Resonant Scanning Confocal A1rHD looks at fluorescently stained materials and can localize cell components or other areas of interest on biological samples. For example, the confocal can look at live anesthetized tiny fish embryos and make a movie of the heart beating and the valves opening and closing. It can also help assess the properties of various materials.

The flow cytometer is used to analyze physical and biochemical properties of living cells. The instrument draws cells into a flow cell where they scatter the light from a laser. The degree of scatter gives information about the size and internal complexity of the cells. In addition by labeling internal molecules (typically proteins) in the cell with fluorescent chemicals, we can obtain information about cell function. Our instrument uses 3 different lasers allowing us to simultaneously examine several proteins at once.

Model: Bruker Ultrashield 500MHz

This instrument analyzes the structure of molecules by evaluating the electromagnetic radiation emitted by certain atomic nuclei when they are subjected to their electromagnetic resonance frequency in a strong magnetic field. Our Brüker Avance DRX 500 MHz NMR spectrometer is equipped with a Z-axis gradient unit and a variable temperature controller, and can be operated with either a 5mm broad-band multinuclear (PABBO) probe or a 5mm 1H/13C/15N (TXI) inverse probe.  This instrument allows chemical scientists at Williams to determine the structures of molecules from a wide variety of projects, ranging from natural product total synthesis, polymer synthesis, materials science and catalyst development research projects, natural product isolation studies, and structure determination of small peptides.

Contact: Silas Brown   [email protected]

The SEM uses a focused electron beam to obtain very high resolution 3 dimensional images of the surface topography of virtually any sample that will fit into the scope. In addition, we can use the SEM to obtain information about the elemental composition of a sample.

The electron microscopes and other scopes are located in the Oberndorf Family Microscopy Suite on the ground floor of Hopper Science Center – Rooms G 08 thru G13.

The observatory houses a professional-grade 24-inch (0.6-m) Cassegrain reflecting telescope from DFM Engineering. It is principally used in introductory and advanced courses for imaging using a FLI PL 16803  CCD camera and a variety of optical filters. It also carries an Optomechanics C-10 spectrograph, recently upgraded with new components and a new Apogee U1107 spectroscopy CCD. The telescope is also used to conduct research on variable massive stars in young star clusters, and in addition, to observe occultations of stars by small bodies in the outer solar system.

Equipped with high-precision, diamond-based cutting, grinding and polishing equipment, the thin sectioning lab prepares solid materials for analysis. Typical preparation creates “thin sections”, samples mounted to glass microscope slides, then ground to a thickness of 30 microns or less. At this thickness, most solid materials transmit light and can be analyzed with an optical microscope. Thin sections are also suitable for scanning electron microscope (SEM) analysis. The lab also produces “bulk mounts”, whole samples set in resin with one side cut and polished. Bulk-mounts are typically analyzed by SEM.

The TEM uses a focused electron beam that can examine sectioned samples at high magnification and resolution.  The fine structure of biological materials as well as nanoparticles and viruses can all be viewed at magnifications up to 500,000x.