Size-dependent ion emission asymmetry of free NaCl nanoparticles excited by intense femtosecond laser pulses.

We report on asymmetric ion emission of size-selected NaCl nanoparticles (d = 100-600 nm) ionized by intense femtosecond laser pulses (λ = 800 nm, peak intensity ∼1013 W cm-2). Velocity map imaging indicates that a higher ion yield is observed in the propagation direction of the laser pulses than in the opposite direction. This asymmetric ion emission is found to be size-dependent and increases with particle size.

Photoelectron angular distribution from free SiO nanoparticles as a probe of elastic electron scattering.

In order to gain quantitative information on the surface composition of nanoparticles from X-ray photoelectron spectroscopy, a detailed understanding of photoelectron transport phenomena in these samples is needed. Theoretical results on the elastic and inelastic scattering have been reported, but a rigorous experimental verification is lacking. We report in this work on the photoelectron angular distribution from free SiO nanoparticles (d = 122 ± 9 nm) after ionization by soft X-rays above the Si 2p and O 1s absorption edges, which gives insight into the relative importance of elastic and inelastic scattering channels in the sample particles.

Coherent control of the ultrafast dissociative ionization dynamics of bromochloroalkanes.

We report on the coherent control of the ultrafast ionization and fragmentation dynamics of the bromochloroalkanes C(2)H(4)BrCl and C(3)H(6)BrCl using shaped femtosecond laser pulses. In closed-loop control experiments on bromochloropropane (C(3)H(6)BrCl) the fragment ion yields of CH(2)Cl(+), CH(2)Br(+), and C(3)H(3)(+) are optimized with respect to that of the parent cation C(3)H(6)BrCl(+). The fragment ion yields are recorded in additional experiments in order to reveal the energetics of cation fragmentation, where laser-produced plasma radiation is used as a tunable pulsed nanosecond vacuum ultraviolet radiation source along with photoionization mass spectrometry.