Water window imaging opportunity

August 21, 2014
Water window imaging opportunity

Ever heard of the water window? It consists of radiations in the 3.3 to 4.4 nanometre range, which are not absorbed by the water in biological tissues. New theoretical findings show that it is possible to develop coherent radiations within the water window. These could be the basis of an optimal technique to obtain a high-contrast image of the biological samples or to be used in high-precision spectroscopy.

Now, a new theoretical study identifies the physical mechanism needed to efficiently generate the harmonic radiations—which are multiples of an incoming 's frequency—at high laser intensities that occur beyond the saturation threshold of atoms and molecules. These findings, aimed at improving conventional methods of coherent radiation production to reach the water window, were recently published in the EPJ D by José Pérez-Hernández from the Centre for Pulsated Laser, CLPU, in Salamanca, Spain, and colleagues.

When an intense and short laser pulse interacts with an atom or molecule, one of the resultant physical processes is the High-order Harmonic Generation (HHG) process, which is capable of changing the driving laser pulse into new harmonic frequencies. HHG also provides a direct way to synthesise atto-second pulses (10-18s range) and produce coherent radiation in the extreme UV range, dubbed XUV and EUV.

In previous similar work, studies focused on hydrogen as the atomic target. In the present work, the authors extend the study to argon atoms—a gas typically providing a high enough frequency conversion efficiency to detect the HHG. The authors use the same formalism as in hydrogen studies, consisting in mathematical equations combined with a quantum mechanical approach using numerical computation and providing a quantitative description of the HHG spectrum. The experimental confirmation of the reported prediction, however, still remains a challenge.

Explore further: New medical device concept could reduce time to diagnose infections

More information: Pérez-Hernández, J. A. et al. (2014). High order harmonic generation at high laser intensities beyond the tunnel regime. European Physical Journal D. DOI: 10.1140/epjd/e2014-50086-6

Related Stories

Changing the color of light

July 23, 2015

Researchers at the University of Delaware have received a $1 million grant from the W.M. Keck Foundation to explore a new idea that could improve solar cells, medical imaging and even cancer treatments. Simply put, they want ...

An elusive molecule—finally revealed

July 13, 2015

Scientists at the University of Arizona have discovered a mysterious molecule with a structure simple enough to make it into high school textbooks, yet so elusive that chemists have argued for more than a century over whether ...

The difference between asteroids and meteorites

June 3, 2015

Asteroids, meteors, and meteorites … It might be fair to say these rocks from space inspire both wonder and fear among us Earthlings. But knowing a bit more about each of them and how they differ may eliminate some potential ...

Recommended for you

A particle purely made of nuclear force

October 13, 2015

Scientists at TU Wien (Vienna) have calculated that the meson f0(1710) could be a very special particle – the long-sought-after glueball, a particle composed of pure force.

Light-optics research could improve medical imaging

October 13, 2015

A team of researchers, including The University of Queensland's Dr Joel Carpenter, has developed echo-less lights that could improve medical imaging inside the body, leading to less-intrusive surgery.

Just a touch of skyrmions

October 13, 2015

Ancient memory devices such as handwriting were based on mechanical energy—but in the modern world they have given way to devices based generally on electrical manipulation.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.