Structure and spin of the low- and high-spin states of Fe(phen) studied by x-ray scattering and emission spectroscopy.

The structure and spin of photoexcited Fe(phen) in water are examined by x-ray scattering and x-ray emission spectroscopy with 100 ps time resolution. Excitation of the low-spin (LS) ground state (GS) to the charge transfer state MLCT leads to the formation of a high-spin (HS) state that returns to the GS in 725 ps. Density functional theory (DFT) predicts a Fe-N bond elongation in HS by 0.

Non-equilibrium dynamics of spin-lattice coupling.

Quantifying the dynamics of normal modes and how they interact with other excitations is of central importance in condensed matter. Spin-lattice coupling is relevant to several sub-fields of condensed matter physics; examples include spintronics, high-T superconductivity, and topological materials. However, experimental approaches that can directly measure it are rare and incomplete.

Room temperature XFEL crystallography reveals asymmetry in the vicinity of the two phylloquinones in photosystem I.

Photosystem I (PS I) has a symmetric structure with two highly similar branches of pigments at the center that are involved in electron transfer, but shows very different efficiency along the two branches. We have determined the structure of cyanobacterial PS I at room temperature (RT) using femtosecond X-ray pulses from an X-ray free electron laser (XFEL) that shows a clear expansion of the entire protein complex in the direction of the membrane plane, when compared to previous cryogenic structures. This trend was observed by complementary datasets taken at multiple XFEL beamlines.

New insights into correlated materials in the time domain-combining far-infrared excitation with x-ray probes at cryogenic temperatures.

Modern techniques for the investigation of correlated materials in the time domain combine selective excitation in the THz frequency range with selective probing of coupled structural, electronic and magnetic degrees of freedom using x-ray scattering techniques. Cryogenic sample temperatures are commonly required to prevent thermal occupation of the low energy modes and to access relevant material ground states. Here, we present a chamber optimized for high-field THz excitation and (resonant) x-ray diffraction at sample temperatures between 5 and 500 K.

Taking a snapshot of the triplet excited state of an OLED organometallic luminophore using X-rays.

OLED technology beyond small or expensive devices requires light-emitters, luminophores, based on earth-abundant elements. Understanding and experimental verification of charge transfer in luminophores are needed for this development. An organometallic multicore Cu complex comprising Cu-C and Cu-P bonds represents an underexplored type of luminophore.

Demonstration of a picosecond Bragg switch for hard X-rays in a synchrotron-based pump-probe experiment.

A benchmark experiment is reported that demonstrates the shortening of hard X-ray pulses in a synchrotron-based optical pump-X-ray probe measurement. The pulse-shortening device is a photoacoustic Bragg switch that reduces the temporal resolution of an incident X-ray pulse to approximately 7.5 ps.

A comparison of methods to assess cell mechanical properties.

The mechanical properties of cells influence their cellular and subcellular functions, including cell adhesion, migration, polarization, and differentiation, as well as organelle organization and trafficking inside the cytoplasm. Yet reported values of cell stiffness and viscosity vary substantially, which suggests differences in how the results of different methods are obtained or analyzed by different groups. To address this issue and illustrate the complementarity of certain approaches, here we present, analyze, and critically compare measurements obtained by means of some of the most widely used methods for cell mechanics: atomic force microscopy, magnetic twisting cytometry, particle-tracking microrheology, parallel-plate rheometry, cell monolayer rheology, and optical stretching.

Large Amplitude Oscillatory Shear Rheology of Living Fibroblasts: Path-Dependent Steady States.

Mechanical properties of biological cells play a role in cell locomotion, embryonic tissue formation, and tumor migration among many other processes. Cells exhibit a complex nonlinear response to mechanical cues that is not understood. Cells may stiffen as well as soften, depending on the exact type of stimulus.

Deposition of Gold Nanotriangles in Large Scale Close-Packed Monolayers for X-ray-Based Temperature Calibration and SERS Monitoring of Plasmon-Driven Catalytic Reactions.

Anisotropic plasmonic particles such as gold nanotriangles have extraordinary structural, optical, and physicochemical properties. For many applications in different fields, it is essential to prepare them in a chemically and physically stable, structurally well-defined manner, e.g.

Using cell monolayer rheology to probe average single cell mechanical properties.

The cell monolayer rheology technique consists of a commercial rotational rheometer that probes the mechanical properties of a monolayer of isolated cells. So far we have described properties of an entire monolayer. In this short communication, we show that we can deduce average single cell properties.