Cutting-edge chemistry funded by Wall Institute

by Sean Kelly
Staff writer

An interdisciplinary and international research team led by one of Canada's top chemists is set to break new ground in the study of electron motion thanks to a $500,000 grant from the Peter Wall Institute for Advanced Studies (PWIAS).

Chemistry Prof. Chris Brion's research team won the annual competition for the institute's Major Thematic Grant to use technology developed at UBC to study the motion of electrons in atoms, molecules and condensed matter. Many have never been studied before.

The objects of study are "orbitals" -- the complex patterns created by electrons as they move in and out around their nuclei at speeds of about 16 million kilometres per hour.

"It's a lot trickier than a photo radar speed trap on University Boulevard," says Brion.

By studying orbitals, the team of 14 leading researchers in the fields of chemistry and biochemistry, physics, engineering, and materials science hopes to gain an understanding of the relation between chemical behavior and electron motion at a fundamental level.

The experiments will focus on the electrons which occupy the outermost, or valence, orbitals. Brion says figuring out how valence orbitals behave is the holy grail of chemistry.

"We now believe that when one molecule meets another, it is the outside, low momentum regions of valence orbitals that initially direct and determine chemical reactivity, chemical bonding, and certain physical behaviors," he explains.

Breakthroughs in computer-aided molecular design, screening and design of drugs, and the development of new materials are some of the possible applications of the research, according to Yenyou Zheng, a member of the research team and a senior research associate in the Chemistry Dept.

Experiments of this kind began with atomic physicists in Italy and Australia in 1973.

Brion and his UBC colleagues began their studies in 1974 and have remained at the forefront of electron motion research ever since.

The key to observing the orbitals is Electron Momentum Spectroscopy (EMS), a technology applied using custom-made machines called multi-channel electron momentum spectrometers.

Inside the spectrometer, atomic or molecular targets are bombarded with an electron beam fired from an electron gun. When struck by an electron from the gun, an electron moving in an atom or molecule is knocked out of its orbital, and both "scattered" electrons ricochet away at the same time. Two sensors pick up the simultaneous strikes, and record the momenta of the two scattered electrons. Knowing the momentum of the electron from the gun, and the momenta of the scattered electrons, the researchers can obtain the momentum of the moving electron before it was knocked out of its orbital.

By repeating this process many times, the characteristic movement, or density distribution, of electrons in particular orbitals can be determined with high accuracy. Once obtained, they can be used to calculate and predict chemical behavior. The bigger the molecule, the more difficult the process becomes.

UBC's first EMS machine, built in 1974, was so slow Brion says that observations for even the simplest molecules required many weeks of electron bombardment night and day. A second generation machine currently in use is 20 times faster -- better, but still slow.

A new machine under construction at UBC is expected to be up to 40,000 times faster than the first machine. Funded by the Natural Sciences and Engineering Research Council and UBC, the machine should be ready this spring.

"We'll be able to study a wider range of atoms, molecules, solids and surfaces," says Zheng.

The new spectrometer has no rival anywhere in the world adds Brion.

"It's designed from scratch and constructed in-house," he says. "We buy components, we scrounge from rubbish heaps and we beg and borrow."

If everything works out, Brion believes further technical refinements could eventually produce a multi-channel spectrometer that would be 400,000 times faster than UBC's first machine.

Along with cutting-edge technology, the experience of the research team impressed the adjudicators who awarded the grant, according to PWIAS Director Kenneth MacCrimmon.

"Considering the range of disciplines and talents represented, the spirit of collaboration of this research team is impressive," he says.

Brion and Zheng are joined by UBC Chemistry professors Delano Chong, Keith Mitchell and Donald Douglas, Chemistry and Biochemistry Prof. Stephen Withers, Physics and Electrical Engineering Prof. Tom Tiedje, and Chemistry senior research associates Glyn Cooper and Bruce Todd. The research team also includes three other scientists based in Canada, and one each from the U.S., Australia, and Germany.

The Peter Wall Institute for Advanced Studies works to bring together UBC researchers and distinguished scholars from around the world, to conduct fundamental research that draws upon and contributes to a variety of disciplines.

MacCrimmon says the electron motion study won unanimous recommendations from an adjudication committee composed of distinguished researchers from every faculty at UBC. The application also received positive appraisals from external experts in five countries.

The deadline for applications for the next major thematic grant the Peter Wall Institute will award is March 2. For more information call the institute at 604-822-4782.