Infrared lasers depict chemical bonds

Infrared lasers depict chemical bonds
MADISON, Wis. — An infrared laser experiment at the University of Wisconsin has turned up a new way to create images of molecules and of the bonds that hold them together. A laboratory setup at the university used a pair of directed laser beams: one to stimulate vibrations in a molecule and the other to read and map the resulting bond pattern.

The technique enhances an established approach to infrared spectroscopy. In the experimental method, a probe beam manipulates the vibrational energy of the molecule. The basic technique, called Doubly Vibrationally Enhanced (Dove) Four Wave Mixing, is similar to medicine's nuclear magnetic-resonance (NMR) technique, but at much higher frequencies.

The technique is expected to be applied to observing chemical reactions in biological organisms since the infrared wavelength is close to the vibrational frequency of water, said John Wright, who performed the experiment with Wisconsin colleague Wei Zhao. Their results were published in the journal Physical Review Letters.

While biological systems constitute a logical first step for applications, the technique is general and could be applied to a variety of chemical reactions, Wright said.