Attosecond Laser Takes Aim at Holy Grail of Chemistry Research
LONDON, March 19, 2012 — Ultrafast pulses of laser light have been fired at oxygen, nitrogen and carbon monoxide molecules and could pave the way toward imaging the movement of atoms and their electrons as they undergo chemical reactions — one of the holy grails of chemistry research.
A team of international researchers from Max Born Institute, FOM-Institute AMOLF and Texas A&M University fired ultrashort laser pulses that span only a few hundred attoseconds at a sample of molecules to map the quick movements of atoms within the molecules as well as the charges that surround them.
Previous research probed at the structure of molecules using a variety of techniques; however, the inherent challenge is to perform these experiments in systems where changes are rapidly occurring on very small time scales.
The scientists used two lasers: The first held the molecule in place, while the second was fired at it. The second laser operated in the extreme ultraviolet region of the electromagnetic spectrum, where the laws of physics allow laser pulses to be produced on an attosecond timescale.
Once in place, short laser pulses were fired at the target molecule in an attempt to dislodge an electron. This photoionization process images atoms and molecules in unprecedented detail.
The samples in the experiment, which existed as a gas, were stable. The research team wanted to monitor in real time the electrical and molecular changes that occurred as an atom underwent a chemical reaction. They intended to do this by triggering a reaction with the laser, breaking the chemical bond that held the molecules together, and using the photoionization method to image the changes that occurred in the molecule as they happened.
“We show that the photoelectron spectra recorded for a small molecule, such as oxygen, nitrogen and carbon monoxide, contains a wealth of information about electron orbitals and the underlying molecular structure,” said Dr. Arnaud Rouzée of Max Born Institute and lead author of the study. “This is a proof-of-principle experiment that electrons ejected within the molecule can be used to monitor ultrafast electronic and atomic motion.”
The study was published March 16 in IOP Publishing’s Journal of Physics B: Atomic, Molecular and Optical Physics as part of a special issue on attosecond science to mark the 10th anniversary of the first attosecond laser pulse.
For more information, visit: www.iop.org
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