Polarized light scattering by aerosols in the marine atmospheric boundary layer

The intensity and polarization of light scattered from marine aerosols affect visibility and contrast in the marine atmospheric boundary layer (MABL). The polarization properties of scattered light in the MABL vary with size, refractive index, number distributions, and environmental conditions. Laboratory measurements were used to determine the characteristics and variability of the polarization of light scattered by aerosols similar to those in the MABL. Scattering from laboratory-generated sea-salt-containing (SSC) [NaCl, (NH4)2SO4, and seawater] components of marine aerosols was measured with a scanning polarization-modulated nephelometer. Mie theory with Gaussian and log normal size distributions of spheres was used to calculate the polarized light scattering from various aerosol composition models and from experimentally determined distributions of aerosols in the marine boundary layer. The modeling was verified by comparison with scattering from distilled water aerosols. The study suggests that polarimetric techniques can be used to enhance techniques for improving visibility and remote imaging for various aerosol types, Sun angles, and viewing conditions

Simultaneous Determination of Fe 3p Spin-Orbit and Exchange Splittings in Photoemission

Spin-resolved core-level photoemission data from the 3p level of ultrathin Fe films [1.4–5.1 monolayers (ML)] epitaxially grown on W(110) have been obtained. A nonlinear least-squares analysis, based on a one-particle Hamiltonian that simultaneously includes core-valence exchange and core-hole spin-orbit interactions, is developed. It is first tested on Fe 2p magnetic circular dichroism (MCD) photoemission spectra and shown to successfully describe the MCD asymmetry data. The model is then used to analyze our thin-film 3p data. With increasing film thickness the spin-orbit splitting (0.67±0.02 eV) remains constant (as expected), the exchange splitting increases from 0±0.12 eV to 0.41±0.05 eV, the average Fe film magnetization (=1.2±0.3μB at 1.4 ML) increases, and the singularity index decreases. The analysis highlights the importance of simultaneously considering all relevant photoemission parameters in extracting meaningful values of the spin-orbit and exchange interactions

Conduction-Electron Screening in the Bulk and at Low-Index Surfaces of Ta Metal

High-resolution core-level photoemission spectra from Ta(100) have been measured. The well-resolved peak from the first atomic layer allows a separate assessment of bulk and surface-layer screening responses: singularity indices αB=0.10±0.01 and α100=0.205±0.025, respectively, are obtained. The measured surface-atom lifetime broadening of 70±20 meV (compared to 37±5 meV in the bulk) is consistent with published Auger–photoemission coincidence measurements. The result for the bulk singularity index has been applied in the analysis of previous data in order to extract the screening response in the first atomic layer of Ta(111) (α111=0.16±0.01) and Ta(110) (α110=0.150±0.015). The trend in surface α’s implies an increasingly atomic character for the surface-layer atoms as one proceeds from Ta(110) to Ta(111) to Ta(100)

Thermally Induced Core-Electron Binding-Energy Shifts in Transition Metals: An ExperimentalInvestigation of Ta(100)

High-resolution photoemission spectra from the 4f7/2 levels of Ta(100) have been obtained between 77 K and room temperature. The data show an increase in both the surface and bulk core-level binding energies (BE’s) as the temperature is raised: between 77 and 293 K the bulk and surface BE’s increase by 31±3 and 13±2 meV, respectively. A model calculation of the bulk binding-energy increase, which is based upon the lattice expansion of the solid, is in good agreement with the experimental results and indicates that the shifts arise from both initial- and final-state effects that are of comparable magnitude. The model is further used to estimate thermally induced shifts for the whole 5d transition-metal series. © 1996 The American Physical Society

Surface Core-Level Shifts and Atomic Coordination at a Stepped W(110) Surface

Core-level 4f7/2 photoemission spectra have been measured from a single, bifacial W crystal, which has both a flat W(110) and a vicinal, stepped W(110) [W(320)] surface. This procedure reduces uncertainties in the quantitative description of peaks in the spectra from W(320). Various analyses, including nonlinear least-squares curve fitting, show that the average surface core-level shift (SCS) for W(320) is only ∼-140 meV, compared to -310 meV for W(110) and that, at a maximum, only two of five terrace rows are isoelectronic to W(110) surface atoms. The absence of a large SCS for the step-edge atoms contradicts earlier interpretations of W(320) core-level spectra and departs significantly from expectations based on atomic-coordination models or tight-binding calculations of a bulk truncated surface. We suggest that systematic errors are responsible for the differences in reported core-level shifts for W(320). Implications of possible step-edge-driven atomic rearrangements are discussed

Mental Health and Information Technology Catalysts as Determinants of Innovative Work Behavior

Interpersonal interactions, such as impromptu face-to-face workplace conversations, facilitate knowledge transfer and spur innovation within individual work roles; however, the move to remote work during the COVID-19 pandemic disrupted these dynamics. This research examines how innovation can be maintained in remote work settings by considering Information Technology (IT) catalysts (a combination of IT mindfulness, IT identity, and IT empowerment) during disruptive events and crises. We also highlight the importance of remote workers’ mental health and coping as precursors for IT catalysts to stimulate innovative work behaviors. Our paper contributes to information systems (IS) theory by establishing remote workers’ mental health and coping as distal factors of innovation and precursors to IT catalysts. In addition, we extend IS theory by establishing the relationships among the IT catalyst factors as well as their impact on innovative work behaviors. Our research provides insights for organizations interested in sustaining innovation, especially during crises or other stress-inducing events or conditions

Femtosecond Thermionic Emission in the Space-Charge Limited Regime

We study femtosecond-laser-pulse-induced electron emission from W(100), Al(110), and Ag(lll) in the sub-damage regime (1–44 mJ/cm2 fluence) by simultaneously measuring the incident-light reflectivity, total electron yield, and electron-energy distribution curves of the emitted electrons. The total-yield results are compared with a space-charge-limited extension of the Richardson-Dushman equation for short-time-scale thermionic emission and with particle-in-a-cell computer simulations of femtosecond-pulsed-induced thermionic emission. Quantitative agreement between the experimental results and two calculated temperature-dependent yields is obtained and shows that the yield varies linearly with temperature beginning at a threshold electron temperature of ~0.25 eV The particle-in-a-cell simulations also reproduce the experimental electron-energy distribution curves. Taken together, the experimental results, the theoretical calculations, and the results of the simulations indicate that thermionic emission from nonequilibrium electron heating provides the dominant source of the emitted electrons. Furthermore, the results demonstrate that a quantitative theory of space-charge-limited femtosecond-pulse-induced electron emission is possible

Oyster Planting Protocols To Deter Losses To Cownose Ray Predation

The utility of shell overlays to oyster (Crassostrea virginica) plantings as a cownose ray (Rhinoptera bonasus) predator deterrence mechanism was examined. Typical industry practice of oyster seed planting was followed in an experimental design employing treatment areas of 0.5-1.0 acre (0.2-0.4 hectare). Areas were prepared in the Lower Machodoc Creek, Virginia, by the initial application of shell to insure a stable substrate under planted seed oysters. Seed oysters were planted using standard industry methods. Experimental areas were located, two upstream and two downstream, of a constriction in the Lower Machodoc that dictated differing physical environments in the respective locations with downstream locations being more exposed to northeast wind-driven stresses and, historically, a greater incidence of ray predation. Once oysters were planted, two of the areas, one upstream and one downstream of the aforementioned constriction, were additionally treated with a shell overlay as a predation deterrent. Oyster seed were planted in the experimental plots in February 2012. Market oysters were harvested from the experimental plots in December 2013 and January 2014. Final harvest data demonstrated that shell overlays do not offer additional protection to planted oyster seed with respect to possible cownose ray predation. Evidence of predation in the form of characteristically broken oyster valves were recorded in all treatment areas. Concurrent stomach content analysis of rays captured at the study location and observations of fouling community associated with the cultured oysters taken during the harvest operation indicate broad dietary preferences for rays when such a variety exists in the foraging region. For rays, oysters are not the singular preferred diet item, although localized and intensive feeding on oysters remains an option with a wide foraging range. Areas without overlay demonstrated higher production than those with shell overlay. Shell overlays are not recommended as predator deterrents for cownose rays in large deployments of unprotected oyster seed

Observation of magnetic circular dichroism in Fe L_{2,3} x-ray-fluorescence spectra

We report experiments demonstrating circular dichroism in the x-ray-fluorescence spectra of magnetic systems, as predicted by a recent theory. The data, on the L_{2,3} edges of ferromagnetic iron, are compared with fully relativistic local spin density functional calculations, and the relationship between the dichroic spectra and the spin-resolved local density of occupied states is discussed