Evaporation of water by extremely strong X-rays

A Korean group led by Professor J. H. Je (Pohang University of Science and Technology) has recently reported some interesting experiments on water vaporization by X-ray photons. The experiments were done at the undulator beamline, XSD 32-ID, Advanced Photon Source in Argonne, USA. It was found that water is vaporized at a rate of 5.5 pL/sec at a 100 msec exposure of 1-Å-wavelength (~13 keV) X-ray irradiation of around 10⁷ photons/μm² (0.1 photons/Ų), which corresponds to a dose rate of ~50 kGy/sec. They also confirmed that water vapor is reversibly condensed during pauses in irradiation. This result suggests that photoionization induces vaporization through the reduction of the surface tension of water. For more information, see the paper, "X-ray-induced water vaporization", B. M. Weon et al., Phys. Rev. E84, 032601 (2011).