Synopsis: X-Ray Absorption Spectroscopy on a Tabletop

A laser-based setup can be used to perform x-ray spectroscopy with a precision rivaling that of experiments at large-scale synchrotron facilities.
Synopsis figure
T. Popmintchev/Univ. of California San Diego; D. Popmintchev/JILA and Univ. of Colorado Boulder

X-ray absorption spectroscopy (XAS) is a versatile tool for chemistry, biology, and materials science. By probing how x rays are absorbed from core electrons of atoms in a sample, the technique can reveal the local structure around selected atoms. XAS measurements are typically performed using the well-controlled x-ray beams of large-scale synchrotron facilities. A new study, however, shows that a tabletop x-ray source driven by lasers can be used to acquire XAS spectra as accurate as those obtained at synchrotrons. The scheme could dramatically expand the availability of XAS.

The setup used by Dimitar Popmintchev of JILA and the University of Colorado, both in Boulder, and his co-workers generates x rays through high-harmonic generation (HHG), in which an infrared laser beam focused on a gas sample creates radiation at much higher frequencies. Previously demonstrated HHG sources haven’t been sufficiently bright at the frequencies needed for most XAS work. But the authors recently developed a source that emits attosecond pulses in a laser-like beam with record brightness at photon energies ranging from 100 to 1600 eV.

With this source, the team demonstrated various types of XAS. They showed that the setup can probe the frequency range containing the resonances of many elements relevant to biochemical and condensed-matter studies; as examples, they acquired accurate spectra for carbon, scandium, and iron. They also measured absorption over a broad frequency range in the “water window,” which is important for probing biological specimens, since water is transparent at these frequencies but carbon isn’t. What’s more, the source’s short pulses could be used in the future to carry out time-resolved XAS experiments that probe ultrafast processes in materials and biomolecules.

This research is published in Physical Review Letters.

–Matteo Rini

Matteo Rini is the Deputy Editor of Physics.


More Features »


More Announcements »

Subject Areas

OpticsCondensed Matter PhysicsPhysical Chemistry

Previous Synopsis

Next Synopsis

Quantum Physics

Seeing Anyons with an STM

Read More »

Related Articles

Synopsis: Two-Face Dipole

Synopsis: Two-Face Dipole

A proposed dipole source of electromagnetic waves can selectively couple its emission into either of two neighboring waveguides. Read More »

Synopsis: ARPES with Cold Atoms
Atomic and Molecular Physics

Synopsis: ARPES with Cold Atoms

A numerical study outlines how to perform measurements on cold atoms that mimic angle-resolved photoemission spectroscopy studies of solids. Read More »

Synopsis: Quantum Simulators Tackle Energy Transfer
Quantum Information

Synopsis: Quantum Simulators Tackle Energy Transfer

A quantum simulator made of two trapped-ion qubits can model quantum effects occurring during energy-transfer processes in molecules. Read More »

More Articles