With a pressure pulse width of . Additionally, the phase of an acoustic pulse is observed to change upon reflection at the liquid–solid interface if bubbles are present, providing a direct proof for laser-induced bubbles.

Plasmonic resonances in metallic nano-triangles have been investigated by irradiating these structures with short laser pulses and imaging the resulting ablation and melting patterns. The triangular gold structures were prepared on Si substrates and had a thickness of 40 nm and a side length of ca. 500 nm. Irradiation was carried out with single femtosecond and picosecond laser pulses at a wavelength of 800 nm, which excited higher order plasmon modes in these triangles. The ablation distribution as well as the local melting of small parts of the nanostructures reflect the regions of large near-field enhancement. The observed patterns are reproduced in great detail by FDTD simulations with a 3-dimensional model, provided that the calculations are not based on idealized, but on realistic structures. In this realistic model, details like the exact shape of the triangle edges and the dielectric environment of the structures are taken into account. The experimental numbers found for the field enhancement are typically somewhat smaller than the calculated ones. The results demonstrate the caveats for FDTD simulations and the potential and the limitations of “near field photography” by local ablation and melting for the mapping of complex plasmon fields and their applications.

Optical experiments on the wetting properties of liquid ⁴He and molecular hydrogen are reviewed. Hydrogen films on noble metal surfaces serve as model systems for studying triple point wetting, a continuous transition between wetting and non‐wetting. By means of optically excited surface plasmons, the adsorbed film thickness for temperatures around, and far below, the bulk melting temperature is measured, and the physical mechanisms responsible for the transition are elucidated. Possible applications for other experiments in pure and applied research are discussed. Thin films and droplets of liquid helium are studied on cesium surfaces, on which there is a first order wetting transition. Our studies concentrate on dynamical observations via surface plasmon microscopy, which provide insight into the morphology of liquid helium droplets spreading at different temperatures. Features corresponding to pinning forces, the prewetting line, and the Kosterlitz‐Thouless transition are clearly observed.

We have investigated the dynamics of flux penetration into thin superconducting YBa2Cu3O7−x films using a magneto‐optic technique with nanosecond time resolution. For films carrying large shielding currents an instability in the magnetic flux distribution is discovered, which can be triggered by a local perturbation, e.g., by a focused laser pulse. The instability develops in the form of fine ramified flux structures, with a propagation speed of the flux front on the order of 5×104 m/s

In this review we consider the development of optical near-field imaging and nanostructuring by means of laser ablation since its early stages around the turn of the century. The interaction of short, intense laser pulses with nanoparticles on a surface leads to laterally tightly confined, strongly enhanced electromagnetic fields below and around the nano-objects, which can easily give rise to nanoablation. This effect can be exploited for structuring substrate surfaces on a length scale well below the diffraction limit, one to two orders smaller than the incident laser wavelength. We report on structure formation by the optical near field of both dielectric and metallic nano-objects, the latter allowing even stronger and more localized enhancement of the electromagnetic field due to the excitation of plasmon modes. Structuring with this method enables one to nanopattern large areas in a one-step parallel process with just one laser pulse irradiation, and in the course of time various improvements have been added to this technique, so that also more complex and even arbitrary structures can be produced by means of nanoablation. The near-field patterns generated on the surface can be read out with high resolution techniques like scanning electron microscopy and atomic force microscopy and provide thus a valuable tool—in conjunction with numerical calculations like finite difference time domain (FDTD) simulations—for a deeper understanding of the optical and plasmonic properties of nanostructures and their applications.

Adsorbates on strong binding substrates like H₂ on Au show triple-point dewetting. To study this phenomenon in detail, we have reduced the van der Waals interaction of the H₂ films with the Au surface, by preplating the substrate with Ne, Ar or CH₄. From a theoretical model, which considers the deformation of the adsorbate by the attractive van der Waals potential and the lattice mismatch due to different lattice constants of adsorbate and substrate, complete wetting is expected when preplating the substrate. Our experiments show, however, that for all combinations of preplated material the equilibrium H₂ film thickness is – apart from small differences – the same as without preplating. This indicates that the present picture of the triple-point wetting of H₂ is incomplete.