Nuclear Magnetic Resonance (NMR) Spectrometers
The Department currently has two Nuclear Magnetic Resonance Spectrometers (described in more detail below); a Bruker 400 MHz superconducting nmr spectrometer and an Anasazi 90 MHz nmr spectrometer, both equipped with multinuclear capabilities. The latter instrument is the result of a major upgrade of our older Varian EM 390 nmr spectrometer, which involves replacing all of the electronics and the probe; only the large permanent magnet is retained.
Bruker 400 MHz Nuclear Magnetic Resonance Spectrometer
The more powerful instrument, is our Bruker 400 MHz, Multinuclear, Superconducting nmr spectrometer, purchased as a result of funding by the National Science Foundation of a matching NSF-CCLI proposal. This instrument, equipped with a 400 MHz superconducting magnet and a variable temperature system, is able to obtain nmr spectra over a wide range of temperatures on almost all nmr-active nuclei, including proton, carbon-13, fluorine-19, and phosphorus-31. The instrument was installed in October 2001 upon completion of the renovation of Griffith Hall 336.
Pictures of students using the instrument computer console and getting ready to drop a sample into the instrument's superconducting magnet are shown here, but be sure to also check out the this link
to see additional pictures of the instrument, as well as a picture of the superconducting magnet being filled with liquid nitrogen.
Anasazi Nuclear Magnetic Resonance Spectrometer
The Anasazi 90 MHz nmr is a smaller, permanent magnet nmr system. Although less powerful than the 400 MHz Bruker nmr, it is also equipped with a multinuclear probe that allows students to obtain nmr data on almost all nmr-active nuclei, including proton, carbon-13 and phosphorus-31. The Anasazi upgrade converts older CW (continuous wave) nmr instruments into more modern FT (Fourier transform) instruments that operate in a pulse mode and at higher sensitivity, allowing data to be obtained at much lower sample concentrations and at a much faster rate.
The original CW instrument (Varian EM 390) with the large, many-knob operator console is shown above on the left, and the computer controlled, Anasazi FT-modified instrument is shown on the right. The upgraded FT instrument retains the original magnet, but has completely new electronics and a new multi-nuclear probe capable of obtaining nmr spectra on a wide variety of nmr-active nuclei.
NMR Spectroscopy - What does it do?
NMR is probably the single most powerful instrument used for identifying the structure of a molecule and our instruments are routinely used by students in several of our advanced laboratory courses, as well as in undergraduate research. These instruments are able to detect each unique type of an nmr-active atom present in a molecule, how many of those atoms are present in the molecule, and whether or not the atoms are adjacent to each other on the molecular framework. For example, in ethanol, which has the molecular formula CH3CH2OH, the NMR technique can determine that there are 3 different kinds of hydrogen atoms in the molecule, i.e., those on the first carbon atom, those on the second carbon atom and the the hydrogen that is attached to the oxygen atom. In addition, this technique can determine that there are three hydrogen atoms on the first carbon atom and two on the second carbon atom and that these carbon atoms are adjacent to each other and not separated by the oxygen atom. The older EM-360 instrument can only detect hydrogen atoms, while the Anasazi-upgraded EM-390 instrument can detect both hydrogen and carbon atoms. In contrast, our new Bruker 400 MHz instrument can detect many other nuclei in addition to carbon and hydrogen, such as phosphorous and nitrogen. If you would like more information about the capabilities of these instruments, please contact Dr. Guillermo Moyna.