Varian Gemini 200 MHz Fourier-Transform (FT) Nuclear Magnetic Resonance (NMR) Spectrometer

The nuclei of certain elements, and their isotopes, behave as though they are spinning about an axis. Two of the nuclei more relevant in Organic Chemistry are Hydrogen and an isotope of Carbon (Carbon-13). The nuclei of these elements can be detected when they are placed in a strong external magnetic field (thereby orienting their spinning axes) and irradiated with electromagnetic energy. At certain magnetic field strengths, the nuclei will absorb the energy from the electromagnetic radiation. Energy absorption occurs as a nuclei flips its direction of spin from being aligned with the magnetic field, to being aligned against the magnetic field. When this spin inversion occurs, the nuclei are said to be in resonance.

The Nuclear Magnetic Resonance (NMR) Spectrometer is an instrument designed to allow the observation of nuclei as they relax from resonance. The NMR spectrometer excites the nuclei and then observes the signal as the energy of the nuclei decays back to the ground state.

Our NMR spectrometer (shown in the picture) is known as a high field 200 MHz NMR. It is composed of a superconducting magnet, with a field strength of approximately 4.7 Tesla, and a 200 MHz radio frequency generator, which we upgraded in 2004 (see NMR Upgrade page). The new electronics (Varian Mercury vX system) for the instrument allow us to observe 1H, 13C, 19F and 31P isotopes. The instrument also has a pulsed field gradient unit which allows us to run experiments in fraction of spectrometer time compared to the older system.

All students in our chemistry program are trained to use this $200,000 instrument during their sophomore year, and they routinely use it throughout the chemistry curriculum. Many students also use this instrument to analyze results from research done with faculty members.