Miniaturized Shock Waves Can Study Molecular Dynamics

September 04, 1998

CHAMPAIGN, Ill. -- A new procedure for investigating materials under extreme conditions using laser-driven shock waves has been developed at the University of Illinois. The miniature shock waves, safe and efficient, can be used to study fundamental processes at the molecular level.

"We have developed a versatile technique for generating and probing shock waves in virtually any material," said Dana Dlott, a U. of I. professor of chemistry. "Our technique opens the door for any research group equipped with a moderate-power, ultrafast laser system to study the effects of shock waves on complex systems of interest in chemistry, biology and medicine."

To generate their miniature shock waves at high repetition rates, Dlott, postdoctoral research associate Selezion Hambir and graduate student Jens Franken use a tabletop picosecond laser system and a special, multilayered shock array target.

First, the laser pulse - focused to an intense spot about 100 microns in diameter - is aimed at the thin outer layer of the target. This "shock generation" layer consists of an absorbing dye and an energetic binder. The molecules absorb the laser energy and explode, sending a shock wave through the sample below. The target is then moved slightly by a motorized platform and the process is repeated - at up to 100 times per second. The resulting shock waves, which have a duration of a few nanoseconds, are called "nanoshocks."

"With nanoshocks, a great deal of energy can be pumped into a sample in a very short time," Dlott said. "Nanoshock pulses can suddenly drive the material to extreme conditions of high pressure, high temperature or large mechanical deformation. These phenomena can then be probed by optical or vibrational spectroscopy, which allows molecular-level behavior to be investigated."

The ultrafast nature of the nanoshock technique makes it a powerful tool for studying the molecular dynamics of complex systems. For example, nanoshocks produce a very fast temperature jump that can initiate a thermochemical reaction. The shock wave rapidly compresses the sample, causing intense heating. Then, as the material springs back, it cools quickly on a subnanosecond time scale.

"It thus becomes possible to obtain spectra of materials that react or decompose too quickly to study by conventional means," Dlott said. "Large organic and biomolecular systems, which have never been studied at high temperatures and pressures, are now within reach."

Shock-wave experiments have typically been carried out at large facilities such as government or military laboratories, Dlott said. "Shocks are generated using explosive charges, gas-driven projectiles or high-energy lasers, but the repetition rate is low and the cost per shock is high. Our nanoshocks are relatively inexpensive and very easy to reproduce."The researchers described the new nanoshock technique at the American Chemical Society national meeting in Boston, Aug. 23-28.

###




University of Illinois at Urbana-Champaign

Related Laser Articles from Brightsurf:

Laser technology: New trick for infrared laser pulses
For a long time, scientists have been looking for simple methods to produce infrared laser pulses.

Sensors get a laser shape up
Laser writing breathes life into high-performance sensing platforms.

Laser-powered nanomotors chart their own course
The University of Tokyo introduced a system of gold nanorods that acts like a tiny light-driven motor, with its direction of motion is determined by the orientation of the motors.

What laser color do you like?
Researchers at the National Institute of Standards and Technology (NIST) and the University of Maryland have developed a microchip technology that can convert invisible near-infrared laser light into any one of a panoply of visible laser colors, including red, orange, yellow and green.

Laser technology: The Turbulence and the Comb
While the light of an ordinary laser only has one single, well-defined wavelength, a so-called ''frequency comb'' consists of different light frequencies, which are precisely arranged at regular distances, much like the teeth of a comb.

A laser for penetrating waves
The 'Landau-level laser' is an exciting concept for an unusual radiation source.

Laser light detects tumors
A team of researchers from Jena presents a groundbreaking new method for the rapid, gentle and reliable detection of tumors with laser light.

The first laser radio transmitter
For the first time, researchers at Harvard School of Engineering have used a laser as a radio transmitter and receiver, paving the way for towards ultra-high-speed Wi-Fi and new types of hybrid electronic-photonic devices.

The random anti-laser
Scientists at TU Wien have found a way to build the 'opposite' of a laser -- a device that absorbs a specific light wave perfectly.

Laser 'drill' sets a new world record in laser-driven electron acceleration
Combining a first laser pulse to heat up and 'drill' through a plasma, and another to accelerate electrons to incredibly high energies in just tens of centimeters, scientists have nearly doubled the previous record for laser-driven particle acceleration at Berkeley Lab's BELLA Center.

Read More: Laser News and Laser Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.