[en] The wetting behavior of ethylene adsorbed on MgO(100) was investigated from 83-135 K using high resolution volumetric adsorption isotherms. The results are compared to ethylene adsorption on graphite, a prototype adsorption system, in an effort to gain further insight into the forces that drive the observed film growth. Layering transitions for ethylene on MgO(100) are observed below the bulk triple point of ethylene (T = 104.0 K). The formation of three discrete adlayers is observed on the MgO(100) surface; onset of the second and third layers occurs at 79.2 ± 1.3 K and 98.3 ± 0.9 K, respectively. Thermodynamic quantities such as differential enthalpy and entropy, heat of adsorption, and isosteric heat of adsorption are determined and compared to the previously published values for ethylene on graphite. The average area occupied by a ethylene molecule on MgO(100) is 22.6 ± 1.1 (angstrom)² molecule^-1. The locations of two phase transitions are identified (i.e., layer critical temperatures at T_c2⁽ⁿ⁼¹⁾ at 108.6 ± 1.7 K and T_c2⁽ⁿ⁼²⁾ at 116.5 ± 1.2 K) and a phase diagram is proposed. Preliminary neutron diffraction measurements reveal evidence of a monolayer solid with a lattice constant of ∼4.2 (angstrom). High resolution INS measurements show that the onset to dynamical motion and monolayer melting take place at 35 K and 65 K, respectively. The data reported here exhibit a striking similarity to ethylene on graphite which suggests that molecule-molecule interactions play an important role in determining the physical properties and growth of molecularly thin ethylene films.

[en] Ru M₃-edge resonant inelastic x-ray scattering (RIXS) measurements of with 27 meV resolution reveals a spin–orbit exciton without noticeable splitting. We extract values for the spin–orbit coupling constant ( meV) and trigonal distortion field energy ( meV) which support the nature of . We demonstrate the feasibility of M-edge RIXS for 4d systems, which allows ultra high-resolution RIXS of 4d systems until instrumentation for L-edge RIXS improves. (paper)

No abstract available

[en] Ptychography is a high-resolution imaging technique, which does not require lenses for image magnification and which provides phase contrast with high sensitivity. Here, we propose to use x-ray ptychography for the imaging of surface structure in crystalline samples. We show that ptychography can be used to image atomic step structures using coherent diffraction patterns recorded along the crystal truncation rod of a crystal surface. In a proof-of-concept experiment on a Pt (111) sample, we present ptychographic reconstructions showing features consistent with surface steps. Due to the penetration power of x-rays, this method could find interesting applications for the study of surface structures under buried interfaces or in harsh environments