Phys. Rev. A 89, 023420 (2014)

Extreme ultraviolet (XUV) pump–probe measurements have made it possible to investigate the electronic and nuclear dynamics of molecular hydrogen on a subfemtosecond scale. A European collaboration of scientists from Greece and Spain has generated ultrashort (∼600 as) pulses in the XUV part of the electromagnetic spectrum via a nonlinear interaction between xenon atoms and femtosecond (33 fs) laser pulses (wavelength, 800 nm; pulse energy, ∼170 mJ) from a Ti:sapphire laser. The XUV pulses were then focused by a split spherical mirror onto a pulsed jet of H2 that was synchronized with the arrival of the XUV pulses. The waist diameter of the focused XUV beam was measured to be 2 ± 1 μm with an intensity in the range 1013–1014 W cm−2. The intense XUV pulses ionized the H2 molecules, producing charged H2+ and H+ products that were detected by a time-of-flight mass spectrometer.