Light is an electromagnetic wave composed of oscillating electric and magnetic fields, the one never occurring without the other. In light-matter interactions at optical frequencies, the magnetic component of light generally plays a negligible role. When we "see" or detect light, only its electric field is perceived; we are practically blind to its magnetic component. We used concepts from the field of metamaterials to probe the magnetic field of light with an engineered near-field aperture probe. We visualized with subwavelength resolution the magnetic- and electric-field distribution of propagating light.

We describe the realization of a phase-sensitive and ultrafast near-field microscope, optimized for investigation of surface plasmon polariton propagation. The apparatus consists of a homebuilt near-field microscope that is incorporated in Mach-Zehnder-type interferometer which enables heterodyne detection. We show that this microscope is able to measure dynamical properties of both photonic and plasmonic systems with phase sensitivity.

We report the energy relaxation of the OH stretch vibration of HDO molecules contained in an HDO:D(2)O water bridge using femtosecond mid-infrared pump-probe spectroscopy. We found that the vibrational lifetime is shorter (~630 ± 50 fs) than for HDO molecules in bulk HDO:D(2)O (~740 ± 40 fs). In contrast, the thermalization dynamics following the vibrational relaxation are much slower (~1.5 ± 0.4 ps) than in bulk HDO:D(2)O (~250 ± 90 fs). These differences in energy relaxation dynamics strongly indicate that the water bridge and bulk water differ on a molecular scale.

We describe a variable path length waveguide setup developed to accurately measure the complex dielectric permittivity of liquids. This is achieved by measuring the complex scattering parameter of the liquid in a waveguide section with a vector network analyzer in combination with an E-band frequency converter. The automated measurement procedure allows fast acquisition at closely spaced intervals over the entire measurement bandwidth: 60-90 GHz. The presented technique is an absolute method and as such is not prone to calibration errors. The technique is suited to investigate low-loss as well as high-loss liquids in contrast to similar setups described previously. We present measurements for a high-loss liquid (water), an intermediate-loss sample (ethanol), and for nearly loss-less n-octane. Due to the available phase information, the present data have an improved accuracy in comparison with literature data.

The discovery of self‐organization principles that enable scalable routes toward complex functional materials has proven to be a persistent challenge. Here, reaction‐diffusion driven, immersion‐controlled patterning (R‐DIP) is introduced, a self‐organization strategy using immersion‐controlled reaction‐diffusion for targeted line patterning in thin films. By modulating immersion speeds, the movement of a reaction‐diffusion front over gel films is controlled, which induces precipitation of highly uniform lines at the reaction front. A balance between the immersion speed and diffusion provides both hands‐on tunability of the line spacing () as well as error‐correction against defects. This immersion‐driven patterning strategy is widely applicable, which is demonstrated by producing line patterns of silver/silver oxide nanoparticles, silver chromate, silver dichromate, and lead carbonate. Through combinatorial stacking of different line patterns, hybrid materials with multi‐dimensional patterns such as square‐, diamond‐, rectangle‐, and triangle‐shaped motifs are fabricated. The functionality potential and scalability is demonstrated by producing both wafer‐scale diffraction gratings with user‐defined features as well as an opto‐mechanical sensor based on Moiré patterning.