Atoms collide like
tennis balls, at
Roland
Piquepaille's Technology Trends, points to
Ultrafast Lasers Take 'Snapshots' as Atoms Collide.
The new data, reported in the Oct. 14 issue
of Physical Review Letters,* provide the equivalent of
missing frames in movies of colliding atoms (see simulated images
in accompanying graphic). As is the case when a tennis ball is hit
by a racquet, the motion is too quick for the eye but can be
detected using short flashes of light. The JILA scientists
collected data on atoms' properties before, during and after
collisions lasting just half a picosecond (trillionth of a second)
using laser "flashes" that were even faster.
In the JILA experiments, about 10 quintillion potassium atoms in a
dense gas were packed into a titanium container just 1 square
centimeter in size and heated to 700 degrees C (almost 1,300
degrees F). With such high temperatures and large numbers of atoms,
the experiment is designed to maximize the number of atom
collisions. Rapidly alternating pulses of laser light then are used
to "freeze frame" the action.
The experiment 'confirm[s] a decades-old theory of how atoms --
like tennis balls -- briefly lose form and energy when they hit
something.'