Nonadiabatic dynamics of electron scattering from adsorbates in surface bands

We present a comparative study of nonadiabatic dynamics of electron scattering in quasi-two-dimensional surface band which is induced by the long-range component of the interactions with a random array of adsorbates. Using three complementary model descriptions of intraband spatiotemporal propagation of quasiparticles that go beyond the single-adsorbate scattering approach we are able to identify distinct subsequent regimes of evolution of an electron following its promotion into an unoccupied band state: (i) early quadratic or ballistic decay of the initial-state survival probability within the Heisenberg uncertainty window, (ii) preasymptotic exponential decay governed by the self-consistent Fermi golden rule scattering rate, and (iii) asymptotic decay described by a combined inverse power-law and logarithmic behavior. The developed models are applied to discuss the dynamics of intraband adsorbate-induced scattering of hot electrons excited into the n=1 image-potential band on Cu(100) surface during the first stage of a two-photon photoemission process. Estimates of crossovers between the distinct evolution regimes enable assessments of the lifespan of a standard quasiparticle behavior and thereby of the range of applicability of the widely used Fermi golden rule and optical Bloch equations approach for description of adsorbate-induced quasiparticle decay and dephasing in ultrafast experiments

Curcuma longa L: pulsed electric field pretreatment followed by subcritical water extraction with addition of acidic modifier

In this study, subcritical water extraction (SWE) was applied to the Curcuma longa that was subjected to the pulse electric field (PEF) pretreatments. In addition, to investigate the possibility of improving the stability of curcuminoids and considering that curcuminoids are stable in an acidic environment, the addition of the HCl acid as an extraction modifier was investigated

Epitaxial Cobalt Oxide Films with Wurtzite Structure on Au(111)

Several-nanometer-thick, closed, and epitaxial cobalt(II) oxide films with wurtzite crystal structure (w-CoO) are grown on Au(111) and their structural and electronic properties analyzed. The structural quality of the (Formula presented.) oriented, oxygen-terminated, and unreconstructed films allow the application of surface-science methods to unravel the properties of this unusual polymorph of CoO and may pave the way for future thin-film applications. An experimental structural analysis by low-energy electron diffraction (LEED-IV) is presented with an excellent agreement between measured and calculated intensity spectra expressed by a Pendry R-factor of (Formula presented.) and few-picometer error bounds in the parameter values. Using scanning tunneling spectroscopy (STS) the bandgap of the semiconducting films is found to be 1.4 ± 0.2 eV. Ultraviolet photoelectron spectroscopy (UPS) confirms the presence of a gap and the position of the Fermi level (E F). The structural results of density functional theory calculations using (hybrid) functionals to treat electron correlations and van der Waals forces agree well with the experimentally determined structure of the antiferromagnetic w-CoO films. In contrast to generalized gradient approximation (GGA)+U calculations, the Heyd–Scuseria–Ernzerhof hybrid functional reproduces the semiconducting nature correctly and predicts surface states in the gap which might pin E F in agreement with STS and UPS

Ohmic heating - a novel approach for gluten-free bread baking

Gluten-free (GF) batters usually present several technological challenges that limit the performance during conventional baking and the resulting product quality. Due to the volumetric heating principle and faster heating rates, ohmic heating (OH) may be advantageous compared with conventional baking. Therefore, the potential of using ohmic heating as a novel approach for gluten-free bread baking was explored. In detail, the effect of different OH process parameters (power input, holding time) on the chemical and functional properties (specific volume, crumb firmness and relative elasticity, pore properties, color, starch gelatinization) and digestibility of breads was investigated. Results showed that GF breads could benefit from the uniform rapid heating during processing, as these breads showed superior functional properties (specific volume, 2.86-3.44 cm3/g; relative elasticity, 45.05-56.83%; porosity, 35.17-40.92%) compared with conventional oven-baked GF bread (specific volume, 2.60 cm3/g; relative elasticity, 44.23%; porosity, 37.63%). In order to maximize bread expansion and the OH performance, it was found that the OH process could be improved by applying the electrical energy in three descending power steps: first step with high power input (in this study, 2–6 kW for 15 s), followed by 1 kW for 10 s, and 0.3 kW for 1–30 min. In total, ohmic baking only needed a few minutes to obtain a fully expanded GF bread. The determination of pasting properties and starch digestibility demonstrated that these breads were comparable or even superior to GF breads baked in a conventional baking oven

Orbital-driven Rashba effect in a binary honeycomb monolayer AgTe

The Rashba effect is fundamental to the physics of two-dimensional electron systems and underlies a variety of spintronic phenomena. It has been proposed that the formation of Rashba-type spin splittings originates microscopically from the existence of orbital angular momentum (OAM) in the Bloch wave functions. Here, we present detailed experimental evidence for this OAM-based origin of the Rashba effect by angle-resolved photoemission (ARPES) and two-photon photoemission (2PPE) experiments for a monolayer AgTe on Ag(111). Using quantitative low-energy electron diffraction (LEED) analysis we determine the structural parameters and the stacking of the honeycomb overlayer with picometer precision. Based on an orbital-symmetry analysis in ARPES and supported by first-principles calculations, we unequivocally relate the presence and absence of Rashba-type spin splittings in different bands of AgTe to the existence of OAM

Surface physics: fundamentals and methods

This work introduces concisely into modern and experimental Surface Physics. Based on many years of teaching experience, the authors present surface-specific properties and complex processes in a plain and descriptive way. Ideal for exam preparation through tasks and comprehension questions. Concepts of Surface Physics: From sample preparation to diverse analysis methods. Many chapters for advanced studies. Prepares for examinations