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Probing the secrets of the atom

Posted by: Date: September 3, 2009 In:

New Chemistry department instrument will help students and profs probe world of the atom

It looks like a rather fat, squat water heater. But to the students and professors gathered around it – or, more accurately, the computer that transmits readouts from it, the machine is pure magic.

It is called a nuclear magnetic resonance spectrometer, or NMR. Today, the students from Professor Neal Yakelis’ organic chemistry lab are trying to figure out the structure of an unknown substance. Yakelis gives the students a rundown on how to order the machine to drop the sample into the depths of the NMR, and then await test results on how protons are oriented in the unknown liquid.

The machine works by an electronic arm plucking out a sample from a rotating tray and slowly lowering it into a tube, which then goes down on a column of air into the machine. There, a powerful magnet that is 200,000 times as strong as the Earth’s magnetic field spins the compound at super-fast speeds. As the machine analyzes the sample, information starts appearing on the computer.

To an untrained eye, the readouts seem like random squiggles and blobs. But the frequencies mean quite a bit to the chemists and the students. It tells them – on a molecular level – how atoms comprising a molecule are bonded together and what parts of the molecule are in motion with respect to the other parts of the molecule. On a more basic scale, it will help them decipher the compound they are looking at.

Some solid samples need to spin inside the magnet at nearly the speed of sound to get the best data.

The spectrometer contains a series of chambers, with the outside chamber forming a vacuum jacket. The outer chamber is then filled with liquid nitrogen, which is at a temperature of minus 321 degrees Fahrenheit. Inside the chamber, a superconducting magnet sits in a broth of liquid helium, which is even colder, at minus 452 degrees Fahrenheit, or just a few degrees above the lowest known temperature in the universe. The magnet is charged with electricity, which aligns the spins of the nuclei in a sample, thereby allowing it to be studied.

After watching their sample drop into the NMR, the students focus their attention back on their computer in front of them. A few clicks of the keyboard and chemistry majors Erin Johnson and Jessica Dottl return to the lab to await their results, which will be e-mailed to them.

Johnson said the automation of the $700,000 machine is amazing. She’s been waiting eagerly since the beginning of the year to use the machine. With good reason.

Undergraduate students like Dottl and Johnson usually do not have access to such a powerful instrument. They know full well that having used the spectrometer – one of the first of its kind located in a West Coast undergrad institution – will help them land future jobs.

“You can say (on your resume) that this is another piece of equipment you’re familiar with,” Dottl said.

Not only for the students, but for the professors of PLU’s chemistry department as well, the nuclear magnetic resonance spectrometer is a dream come true. It’s easy to see they still can’t quite believe, after two years of waiting and receiving a National Science Foundation grant they didn’t expect to get, that it is finally here.

“When the crates came,” said Yakelis, “we were very excited.”

The grant to purchase the NMR was a collaborative effort by chemistry faculty led by Professor Craig Fryhle. The machine is now in full display on the north side of a glass-walled laboratory at the Rieke Science Center on lower campus. Rebuilding the north side of Rieke to support the unique device – including Professor Dean Waldow’s “science on display” glass enclosure – brought the NMR cost to more than $1 million, all of which was paid for by sources outside the university.

Eventually, the group sees not only students using the machine for student-faculty research, but local community and four-year colleges bringing samples over as well. The chemistry faculty members plan to have Webcasts from the NMR lab to teach local college and high school students about NMR spectrometry.

“This is really going to be the crown jewel of the instruments in our department,” Waldow said.

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