A
team of international researchers have fired ultra-fast shots of light
at oxygen, nitrogen and carbon monoxide molecules as part of a
development aimed at mapping the astonishingly quick movements of atoms
within molecules, as well as the charges that surround them. The
ultra-short laser that spans only a few hundred attoseconds—an
attosecond is equivalent to one quintillionth of a second—was fired in a
sample of molecules and could pave the way towards imaging the movement
of atoms and their electrons as they undergo a chemical reaction—one of
the holy grails of chemistry research.
This latest study has been published on March 16, as part of a special issue on attosecond science, in IOP Publishing’s Journal of Physics B: Atomic, Molecular and Optical Physics to mark the 10th anniversary of the first ever attosecond laser pulse.
Previous
research has been able to probe 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
researchers used two lasers in their experiments: the first held the
molecule in place whilst the second was fired at it. The second laser
operated in the extreme ultra-violet region of the electromagnetic
spectrum as this is one of only two regions—X-ray being the other—where
the laws of physics allow laser pulses to be produced on an attosecond
timescale.
Once
the target molecule was in place, short pulses of the laser were fired
at in an attempt to dislodge an electron. This process, known as
photoionization, allows atoms and molecules to be imaged in
unprecedented detail as the ejected electrons carry crucial information
about where it came from.
In
this experiment, the samples, which existed as a gas, were stable,
meaning no reactions were taking place; however, the major goal of the
research team is to monitor the electrical and molecular changes, in
real-time, that occur as atoms undergo a chemical reaction.
They
intend to do this by triggering a reaction with the laser, breaking a
chemical bond that holds molecules together, and then using the
described technique to image the changes that occur in the molecule as
they happen.
Lead
author of the study Dr. Arnaud Rouzée from the Max-Born-Institute said:
“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.
“This
is a proof-of-principle experiment that electrons ejected within the
molecule can be used to monitor ultrafast electronic and atomic motion.”
Source: Institute of Physics
