We are fortunate to have received a grant from the National Science Foundation (CHE-0521075) through the Major Research Instrumentation program for a new NMR spectrometer. The system we chose is a Bruker Avance II 400 MHz spectrometer system. The magnet is a 9.4T superconducting solenoid operating at a nominal proton frequency of 400 MHz. The magnet is actively shielded to produce a minimal magnetic footprint. The cryostat is an ultra-long hold dewar with a nominal 180 day fill interval. It has exactly the same dimensions as our prior AC-250 magnet and because of the active shielding, the magnetic footprint is also identical. The new spectrometer was installed in the spring of 2006, following decommissioning of our old AC-250 system and renovation of S-034A where it is now housed. The AVII-400 is managed by Dr. Richard Fitch.
The AVII-400 is our primary research NMR and is also used for teaching (in addition to the EFT-60). The instrument is equipped with a temperature control accessory for room temperature to 0oC operation, facilitating long acquisitions and variable temperature capability from -150oC to +180oC operation. The probe is broadbanded with automatic tuning and matching capability and pulsed-field gradient capacity. This facilitates remote operation and automation (see below), as well as gradient and simplex shimming. The spectrometer is a four-channel z-gradient system, which is capable of the complete suite of 1D-3D experiments not requiring horizontal gradients.
The spectrometer is also equipped with a BACS automatic sample changer accessory. The sample changer allows us to make maximum use of our instrument as it removes the need for the researcher or student to be present to place the sample in the magnet. Automation allows us to run the instrument 24/7 and enables more and longer experiments to be run during nights and weekends, when the instrument might otherwise be idle. This benefits researchers who may have large numbers of samples or need long acquisition times. It also benefits our laboratory course students, who can acquire high-resolution spectra, including 13C and 2D experiments, which are often not run due to time constraints.
A spectrometer interface, ICONNMR, is served on the web to the campuses of ISU, St. Mary-of-the-Woods College, and Rose-Hulman Institute of Technology. This allows students and researchers at these institutions convenient access to the instrument.