Physicists at JILA, a joint venture of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder, have created the first “frequency comb” in the extreme ultraviolet band of the spectrum, high-energy light less than 100 nanometers (nm) in wavelength. Laser-generated frequency combs are the most accurate method available for precisely measuring frequencies, or colors, of light.

In reaching the new band of the spectrum, the JILA experiments demonstrated for the first time a very fine mini-comb-like structure within each subunit, or harmonic, of the larger comb, drastically sharpening the measurement tool.

The new comb, described in the Feb. 2, 2012, issue of the journal Nature, confirms and expands on the JILA group’s 2005 claim of the ability to generate extreme ultraviolet (EUV) frequencies for making precise measurements in that part of the electromagnetic spectrum. The new tool can aid in the development of “nuclear clocks” based on ticks in the nuclei of atoms, and measurements of previously unexplored behavior in atoms and molecules.

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