Multi-color imaging of magnetic Co/Pt heterostructures.

We present an element specific and spatially resolved view of magnetic domains in Co/Pt heterostructures in the extreme ultraviolet spectral range. Resonant small-angle scattering and coherent imaging with Fourier-transform holography reveal nanoscale magnetic domain networks via magnetic dichroism of Co at the M edges as well as via strong dichroic signals at the O and N edges of Pt. We demonstrate for the first time simultaneous, two-color coherent imaging at a free-electron laser facility paving the way for a direct real space access to ultrafast magnetization dynamics in complex multicomponent material systems.

10-Hz grazing--incidence pumped Ni-like Mo x-ray laser.

The operation of a Ni-like Mo x-ray laser at 18.9 nm with a repetition rate of 10 Hz has been demonstrated. The laser has been pumped applying the grazing incidence pump arrangement, where a short (picoseconds) pulse irradiates a Mo plasma column generated by a long (a few hundred picoseconds) pulse.

Efficient deactivation of a model base pair via excited-state hydrogen transfer.

We present experimental and theoretical evidence for an excited-state deactivation mechanism specific to hydrogen-bonded aromatic dimers, which may account, in part, for the photostability of the Watson-Crick base pairs in DNA. Femtosecond time-resolved mass spectroscopy of 2-aminopyridine clusters reveals an excited-state lifetime of 65 +/- 10 picoseconds for the near-planar hydrogen-bonded dimer, which is significantly shorter than the lifetime of either the monomer or the 3- and 4-membered nonplanar clusters. Ab initio calculations of reaction pathways and potential-energy profiles identify the mechanism of the enhanced excited-state decay of the dimer: Conical intersections connect the locally excited 1pipi* state and the electronic ground state with a 1pipi* charge-transfer state that is strongly stabilized by the transfer of a proton.