Subrelativistic Alternating Phase Focusing Dielectric Laser Accelerators.

We demonstrate a silicon-based electron accelerator that uses laser optical near fields to both accelerate and confine electrons over extended distances. Two dielectric laser accelerator (DLA) designs were tested, each consisting of two arrays of silicon pillars pumped symmetrically by pulse front tilted laser beams, designed for average acceleration gradients 35 and 50  MeV/m, respectively. The DLAs are designed to act as alternating phase focusing (APF) lattices, where electrons, depending on the electron-laser interaction phase, will alternate between opposing longitudinal and transverse focusing and defocusing forces.

Probing lithium mobility at a solid electrolyte surface.

Solid-state electrolytes overcome many challenges of present-day lithium ion batteries, such as safety hazards and dendrite formation. However, detailed understanding of the involved lithium dynamics is missing due to a lack of in operando measurements with chemical and interfacial specificity. Here we investigate a prototypical solid-state electrolyte using linear and nonlinear extreme-ultraviolet spectroscopies.

Polarization-Resolved Extreme-Ultraviolet Second-Harmonic Generation from LiNbO_{3}.

Second harmonic generation (SHG) spectroscopy ubiquitously enables the investigation of surface chemistry, interfacial chemistry, as well as symmetry properties in solids. Polarization-resolved SHG spectroscopy in the visible to infrared regime is regularly used to investigate electronic and magnetic order through their angular anisotropies within the crystal structure. However, the increasing complexity of novel materials and emerging phenomena hampers the interpretation of experiments solely based on the investigation of hybridized valence states.

Extreme Ultraviolet Second Harmonic Generation Spectroscopy in a Polar Metal.

The coexistence of ferroelectricity and metallicity seems paradoxical, since the itinerant electrons in metals should screen the long-range dipole interactions necessary for dipole ordering. The recent discovery of the polar metal LiOsO was therefore surprising [as discussed earlier in Y. Shi et al.