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At least 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Stratospheric Temperature and Ozone Impacts of the Hunga Tonga-Hunga Ha'apai Water Vapor Injection

The January 2022 eruption of the Hunga Tonga-Hunga Ha'apai underwater volcano injected a large amount of water vapor into the mid-stratosphere. This study uses model simulations to investigate the resulting stratospheric impacts out to 2031. Maximum radiatively-driven model temperature changes occur in the Southern Hemisphere (SH) subtropics in April–May 2022, with warming of ∼1 K in the lower stratosphere and cooling of 3 K in the mid-stratosphere. The radiative cooling combined with adiabatic cooling driven by the quasi-biennial oscillation meridional circulation explains the near-record cold anomaly observed in the SH subtropical mid-stratosphere. Projected ozone responses maximize in 2023–2024 as the water vapor plume is transported globally throughout the stratosphere and mesosphere. The excess H2O increases the OH radical, causing a negative global ozone response (2%–10%) in the upper stratosphere and mesosphere due to increased odd hydrogen-ozone loss, and a small positive ozone response (0.5%–1%) in the mid-stratosphere due to interference of the NOx catalytic loss cycle by the additional OH. In the lower stratosphere, the excess H2O is projected to increase polar stratospheric clouds and springtime halogen-ozone loss, enhancing the Antarctic ozone hole by 25–30 DU in 2023. Arctic impact is small, with maximum additional ozone loss of 4–5 DU projected in spring 2024. These responses diminish after 2024 to be quite small by 2031, as the excess H2O is removed from the stratosphere with a 2.5-year e-folding time. Given the year-to-year variability of the stratosphere, the magnitudes of these ozone responses may be below the threshold of detectability in observations.

stratosphere↗
DOE OSTI2026

Carbon dioxide, water vapor and methane soil efflux (soil respiration) in a Pinus palustris root exclusion in Georgetown, SC

This dataset contains processed data from a combination of survey flux chambers and long-term automated flux chambers. Soil flux measurements were conducted from June 2023 through December 2025 in a mature longleaf pine forest in Georgetown, SC. Soil respiration measurements were conducted approximately biweekly for two and a half years, before and after a root exclusion that took place on May 5, 2024. Processed, QAQC’d data for the treatment (root exclusion) and control (roots intact) before and after the root exclusion can be found in the file: 1_DATA_ESS_DOE_HR_RS_HB2_QAQC_Survey_Data_20260223.csv. Two multiday deployments were also conducted prior to the root exclusion using long-term automated chambers to continuously monitor greenhouse gas soil efflux. Processed, QAQC’d data for both long-term deployments can be found in the file: 2_DATA_ESS_DOE_HR_RS_HB2_QAQC_Longterm_Data_20260209.csv. Raw and working data files (.json, .81x, & .82z format) from LI-COR equipment are included for reference and can be accessed using SoilFluxPro software. CSV metadata files describe the raw data and modifications made using SoilFluxPro v5 and Matlab R2024b, as well as formatting and units for processed CSVs. Matlab code is included for reading in the processed CSVs, with sample figures comparing treatment and control. This research was performed as part of the project: “Improving models of stand and watershed carbon and water fluxes with more accurate representations of soil-plant-water dynamics in southern pine ecosystems”, which examines in part the effects hydraulic redistribution on soil efflux of carbon dioxide, water vapor and methane, as well as soil moisture and temperature in a southern pine ecosystem with sandy soils and high water table.

CARBON DIOXIDE FLUX↗
DOE OSTI2026

Carbon dioxide, water vapor and methane soil efflux (soil respiration) in a Pinus palustris restoration site in Georgetown, SC

This dataset contains processed data from a combination of survey flux chambers and long-term automated flux chambers. Biweekly soil flux measurements were conducted from June 2023 through December 2025 at a longleaf pine restoration site in Georgetown, SC. Processed, QAQC’d data can be found in the file: 1_DATA_ESS_DOE_HR_RS_HB3_QAQC_Survey_Data_20260223.csv. Raw and working data files (.json, & .81x format) from LI-COR equipment are included for reference and can be accessed using SoilFluxPro software. CSV metadata files describe the raw data and modifications made using SoilFluxPro v5 and Matlab R2024b, as well as formatting and units for processed CSVs. Matlab code is included for reading in the processed CSVs. This research was performed as part of the project: “Improving models of stand and watershed carbon and water fluxes with more accurate representations of soil-plant-water dynamics in southern pine ecosystems”, which examines in part the effects hydraulic redistribution on soil efflux of carbon dioxide, water vapor and methane, as well as soil moisture and temperature in a southern pine ecosystem with sandy soils and high water table.

CARBON DIOXIDE FLUX↗
DOE OSTI2022

Vapor–Fed Electrolyzers for Carbon Dioxide Reduction Using Tandem Electrocatalysts: Cuprous Oxide Coupled with Nickel–Coordinated Nitrogen–Doped Carbon

We report ethylene is particularly attractive due to its major importance as a feedstock for various applications including the polymer industry. As such, catalyst and electrolyzer developments are crucial to achieve industrially relevant ethylene production and efficiency levels. In this work, a tandem electrocatalyst composed of copper nanocubes and nickel-coordinated nitrogen-doped carbon (NiNC) is presented, which is integrated into gas diffusion electrodes (GDEs) for direct conversion of vapor-fed CO 2 into ethylene. Evaluation of tandem GDEs in the vapor-fed flow electrolyzer shows significantly increased ethylene selectivity in terms of faradaic efficiency and C 2 H 4 /CO ratio compared to a non-tandem copper GDE. The enhancements are attributed to the increased local CO availability near the copper surface via effective CO 2 to CO conversion on neighboring NiNC. The experimental results are validated by 3D resolved continuum simulations, which show increased flux of higher-order prod-ucts with the added CO flux from NiNC. The practical viability of Cu/NiNC catalyst is further evaluated in a membrane electrode assembly electrolyzer, achieving 40% FE toward ethylene at 150 mA cm -2 and 3.2 V. These find-ings highlight the high selectivity and formation rate of ethylene achieved by successful device integration of the Cu/NiNC catalyst, demonstrating the potential for implementation in large-scale sustainable CO 2 electrolyzers.

36 MATERIALS SCIENCE↗
DOE OSTI2021

ZIF‐8 Membrane Permselectivity Modification by Manganese(II) Acetylacetonate Vapor Treatment

Abstract Vapor‐phase treatment of ZIF‐8 membranes with manganese(II) acetylacetonate (Mn(acac) 2 ) allows permselectivity tuning. Propylene/propane selectivity increases from 31 to 210 after the Mn(acac) 2 treatment at 165 °C for 30 min, while selectivities increase from 14.6 to 242 for H 2 /CH 4 , from 2.9 to 38 for CO 2 /CH 4 , from 2.4 to 29 for CO 2 /N 2 , and from 2.9 to 7.5 for O 2 /N 2 , after Mn(acac) 2 treatment at 175 °C for 30 min. Stable equimolar propylene/propane mixture selectivity of 165 at ambient temperature and 4 bar equimolar feed with a propylene flux of 8.3×10 −4 mol m −2 s −1 is established. A control experiment excludes thermal treatment alone causing these changes. XPS analysis reveals the presence of Mn(acac) 2 on the outer surface of the vapor‐treated ZIF‐8 membranes while no other changes are detectable by X‐ray diffraction and infrared spectroscopy.

Hayashi, Mikio↗
DOE OSTI2023

Water vapor transport through bioenergy grass residues and its effects on soil water evaporation

Miscanthus is a productive perennial grass that is suitable as a bioenergy crop in “marginal” lands (e.g., eroded soils) with low water holding capacity. However, little is known about the impact of miscanthus residues on vapor transport and soil water budgets. Laboratory experiments were conducted to measure the vapor conductance through miscanthus residues and its effect on soil water evaporation. The ranges for the length, width, and thickness of residue elements were 0.5–9.0, 0.1–0.5, and 0.1–0.5 cm, respectively. Average residue areal, bulk, and skeletal densities were 0.88 kg m –2 , 24 kg m –3 , and 1006 kg m –3 , respectively, giving a porosity of 0.98 m 3 m –3 . A power function described the decrease in conductance with increasing residue load. The corresponding conductance for a residue load of 0.88 kg m –2 was 1.6 mm s –1 . During the first days of a 60-day drying experiment, cumulative evaporation showed logarithmic decay with increasing residue load. Conversely, cumulative evaporation during the last days of the study showed little difference between treatments. Measurements indicated that there is a “critical” residue load (~1.0 kg m –2 ) beyond which evaporation no longer decreases appreciably when the soil is under the stage 1 evaporation regime. Results suggest that soil water conservation in marginal lands may be accomplished by maintaining moderate amounts of bioenergy grass residue covering the soil. Determining “critical” loads for different residue types is a knowledge gap that merits further research.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Off-design performance of an organic Rankine-vapor compression cooling cycle using R1234ze(E)

In this study, a 264 kW th organic Rankine-vapor compression cycle (ORVC) was experimentally tested over a range of conditions to quantify the individual impact of off-design external conditions. The ORVC was designed to recover waste heat at 91 °C, reject heat to a liquid condenser stream at 30 °C, and produce chilled water at 7 °C. Here, the condenser heat rejection temperature was varied from 16.6 °C to 32.6 °C, the chilled water delivery temperature was varied between 2.1 °C and 13.1 °C, and the heat input temperature was varied from 91 °C to 120 °C. As the condenser heat rejection temperature decreased, the coefficient of performance (COP) of the ORVC improved from 0.558 at 30 °C to 0.682 at 16.6 °C, despite a reduction in compressor isentropic efficiency. Although the chilled water temperature variation had almost no impact on the organic Rankine cycle performance, the compressor efficiency decreased when the delivery temperature was below 7 °C. At the highest chilled water temperature, 13.1 °C, the COP of the ORVC was 0.643. Compressor stall was noted when the condenser heat rejection temperature was greater than 32.6 °C and the chilled water delivery temperature was below 2.1 °C. Increasing the driving heat source inlet temperature improved the COP of the ORVC and the thermal efficiency of the organic Rankine power cycle, while decreasing the efficiency of the compressor and the COP of vapor compression cycle. In addition, the integrated part load value of the system was determined through experimentation to be 0.682, which provides a realistic estimate of real-world performance.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2020

Surface Chemistry of Liquid Bismuth under Oxygen and Water Vapor Studied by Ambient Pressure X-ray Photoelectron Spectroscopy

Bismuth (Bi) has a fairly low melting point of 544 K making it practical as a liquid metal medium in a number of applications. Under ambient atmospheric conditions the surface of solid Bi oxidizes. While the solid Bi interface has been fairly well characterized with surface science studies upon exposure to oxygen, to date little is known about the molecular level reactivity of the liquid interface. Here, using ambient pressure X-ray photoelectron spectroscopy the liquid-gas interfacial chemistry of Bi was examined upon exposure to oxygen gas and water vapor at 550 K up to a maximum pressure of 0.5 Torr. Water vapor remained unreactive towards the liquid interface over the entire pressure range. Oxygen remined unreactive up to 10 –4 Torr, whereas above this pressure oxidation was observed forming Bi 2 O 3 . The oxidation exposure onset was > 5 x 10 5 Langmuirs, significantly higher than what is required for solid Bi interfaces.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Vapor-phase grafting of a model aminosilane compound to Al 2 O 3 , ZnO, and TiO 2 surfaces prepared by atomic layer deposition

Atomic layer deposition (ALD) is a highly versatile surface functionalization technique that can conformally coat both planar and porous substrates. Here we use ALD metal oxide layers to establish a well-defined starting surface for vapor-phase surface organic modification. Vapor-phase (3-aminopropyl)triethoxysilane (APTES) surface silanization of ALD Al 2 O 3 , ZnO and TiO 2 surfaces were studied at 100 °C, 150 °C and 200 °C. In situ quartz crystal microbalance (QCM) and Fourier-transform infrared (FTIR) spectroscopy measurements, and ex situ atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) measurements showed uniform monolayer silane formation through self-limiting APTES reaction. We observed a higher surface density of grafted APTES species following silanization at 100 °C compared to 200 °C, and we attribute this to the temperature-dependent reactivity of the surface hydroxyls and changes in the mode of APTES reaction. The FTIR and XPS measurements revealed that APTES reacts with Al 2 O 3 and ZnO exclusively through metal siloxy bond formation. However, APTES reacts with TiO 2 through both siloxy bond formation and ammonium salt formation via the amine group.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Comparing approaches for introducing polycyclic aromatic hydrocarbons to Ge(001) to seed graphene nanoribbon synthesis by CH 4 chemical vapor deposition

Here, we evaluate two approaches for introducing polycyclic aromatic hydrocarbons (PAHs) to a graphene catalyst substrate as part of a two-step chemical vapor deposition (CVD) process for growing graphene nanoribbons (GNRs). In this process, PAHs first form graphene-like seeds on Ge, and then GNRs are subsequently evolved from these PAH-derived seeds via substrate-mediated anisotropic growth kinetics during the CVD of CH4. The first seeding approach sublimes controlled doses of PAH thin films into the CVD chamber, while the second delivers PAHs directly from the vapor phase at set concentrations. Using these two approaches, we measure the dependence of GNR density on PAH dose and compare the experimental results with predictions from a rate model of PAH diffusion, desorption, and clustering. We find that PAHs that more strongly adsorb to the catalyst surface (generally larger PAHs) desirably remain more individualized prior to GNR evolution whereas smaller, more weakly bound PAHs aggregate into larger clusters with various sizes on Ge that are undesirable for synthesizing more monodisperse GNRs. As a result, this work is important because it offers a framework that enables the rational selection and design of seed molecules, advancing anisotropic GNR CVD synthesis.

CVD↗
DOE OSTI2022

Bridging knowledge gaps in liquid- and vapor-fed CO 2 electrolysis through active electrode area

Increased use of gas diffusion electrodes for CO 2 electroreduction widens the experimental phase space that was previously inaccessible using foil electrodes, raising fundamental questions over the impacts of key variables that translate between liquid- and vapor-fed CO 2 electrolysis systems. This work focuses on studying the interplay of current-potential profiles and electrochemically active surface area (ECSA) by implementing a Cu nanoflower catalyst morphology. The results show decreased overpotentials as much as 460 and 174 mV for foil and gas diffusion electrodes, respectively, while maintaining or improving multi-carbon product current density. Furthermore, these overpotential shifts and product activities normalized by ECSA lead to current-potential relationships akin to those of the Tafel description, which are found through a continuum model to be useful for describing the roughness dependence for both liquid- and vapor-fed systems. This analysis establishes a holistic approach for establishing catalyst design criteria to improve materials development for CO 2 .

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Evaluation of hybrid evaporative-vapor compression air conditioners for different global climates

Currently, a majority of global residential air-conditioning requirements are met using cooling systems based on the vapor compression cycle (VCC). To meet the future demand for space cooling and to reduce the corresponding environmental impact, there is a need for alternative cooling systems which require less resources and exhibit a higher coefficient of performance (COP). One of proposed alternatives is called the hybrid evaporative-vapor compression (HEVC) cycle, which utilizes adiabatic latent cooling in combination with the VCC. In this paper, we conducted a feasibility analysis of a HEVC system by comparing its performance to that of VCC for various global climates. To accomplish this, we developed and validated models to simulate the performance of residential VCC and HEVC systems. ASHRAE weather data and design conditions were then used to compare the performance of the two systems. In general, HEVC systems are best suited for hot arid climates with energy reduction greater than 20%. Conversely, humid climates are not suitable for HEVC adoption due to degraded performance of evaporative coolers in these climates. In addition to comparing the energy savings from HEVC systems, it is also critical to analyze their water consumption. Generally, climates that benefit the most from HEVC technology tend to also experience water scarcity issues. Thus, both the energy savings and water consumption of HEVC systems must be analyzed to guide the discussion on their adoption.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

A simple and effective five-equation two-phase numerical model for liquid-vapor phase transition in cavitating flows

Numerical difficulties, notably the non-monotonic behavior of the Wood speed of sound and the volume fraction positivity, associated with the reduced five-equation two-phase flow model of Kapila et al. (2001) [A.K. Kapila, R. Menikoff, J.B. Bdzil, S.F. Son, D.S. Stewart, 2001. Two-phase modeling of deflagration-to-detonation transition in granular materials: reduced equations, Physics of Fluids 13(10), 3002–3024] have been resolved in the past through the introduction of a frozen speed of sound and an algebraic approach for mechanical relaxation afforded by a pressure non-equilibrium six-equation model proposed by [R. Saurel, F. Petitpas, R.A. Berry, 2009. Simple and efficient relaxation methods for interfaces separating compressible fluids, cavitating flows and shocks in multiphase mixture, J. Comput. Phys. 228, 1678–1712]. By contrast, it is explored and demonstrated in this work that these difficulties can in fact still be resolved within the numerical scheme for solving the reduced five-equation model by numerically replacing the Wood speed of sound for the estimates of wave speeds in the approximate Riemann solver HLLC with the monotonic mixture speed of sound for a transport five-equation model. For shock interface (artificial mixture separating pure or nearly pure fluids) interaction problems, with the apparent advantage of monotonic behavior of the speed of sound in the interface, the effect of the numerical replacement is also confined to the interface. Differences other than the behavior of the speed of sound within the interface in the solutions due to the replacement diminish with increasing resolution when reasonable solution can be obtained with Wood speed of sound. For cavitating/expansion problems in physical fluid mixture, it is pointed out and explained why acoustics in the numerical solutions still propagate at the Wood speed of sound (therefore consistent with the reduced five-equation model) even though in some cases a much higher speed of sound like the numerical replacement above for solving the reduced five-equation model or the frozen speed of sound for solving a six-equation model is used for the estimates of wave speeds in the HLLC scheme. A variant of the five-equation two-phase flow model by Saurel et al. (2008) [R. Saurel, F. Petitpas, R. Abgrall, 2008. Modelling phase transition in metastable liquids: application to cavitating and flashing flows, J. Fluid Mech. 607, 313–350] is then constructed for liquid-vapor phase transition in cavitating flows. The relaxation toward thermo-chemical equilibrium during phase transition is achieved by solving a simple system of algebraic equations for the equilibrium state variables for better efficiency, following Pelanti and Shyue (2014) [M. Pelanti, K.-M. Shyue, 2014. A mixture-energy-consistent six-equation two-phase numerical model for fluid with interfaces, cavitation and evaporation waves. J. Comput. Phys. 259, 331–357]. Therefore, the current model retains both the simplicity afforded by the five-equation model and the efficiency of the algebraic relaxation solver. An alternative algebraic approach for handling the non-conservative term (the so-called K∇ · u term) in the reduced five-equation model for mechanical equilibrium of a liquid-vapor mixture is also explored by enforcing the thermal equilibrium at the same time. Finally, numerical results of sample tests in both one and two dimensions in the literature as well as that in three dimensions demonstrate the effectiveness and ability of the proposed model to simulate cavitating flows. An interesting mechanism of shock generation by acoustics in water due to phase transition is then found by the numerical simulations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Calorimetric metal vapor adsorption energies for characterizing industrial catalyst support materials

Many important catalysts and electro-catalysts for energy and environmental technologies involve late transition metal atoms and nanoparticles dispersed across the surface of high-surface-area support materials, for example, oxide nanoparticles. The surface reactivity and long-term stability against deactivation of these materials depends strongly on the strength of bonding of the metal atom and nanoparticles to the support surface. Here, we introduce a novel calorimetry method that implements a LiTaO 3 crystal for heat detection and extends metal adsorption calorimetry to surfaces of nanomaterials that are deposited from liquid solutions, as is typical when preparing industrial catalyst supports. This allows one to measure the strength of metal atom bonding and the adhesion energy of metal nanoparticles to clean surfaces of technologically relevant catalyst supports. We demonstrate that here by measuring the heat of Ag vapor adsorption onto the clean surfaces of high-surface-area TiO 2 anatase powdered support materials (i.e., 5-nm-diameter nanoparticles). These heats of adsorption show a pulse-to-pulse standard deviation of only 9.3 kJ/mol (3.3%) for pulses containing only 1% of a monolayer of Ag vapor, with potential for a 5-fold reduction in noise if used with another metal evaporator. The calorimeter was also proven to work well measuring heats of Ag adsorption on calcium niobate(001) nanosheets deposited as thin films from liquid solution. Here, this calorimeter opens up the possibility of using metal adsorption calorimetry to screen catalyst support materials for the strengths with which they bind metal atoms and metal nanoparticles, offering new opportunities to discover better support materials or for basic scientific study of structure / function relationships with respect to metal / support bond energies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Corrosion behavior of a series of combinatorial physical vapor deposition coatings on SiC in a simulated boiling water reactor environment

Here, the simulated boiling water condition corrosion properties of multilayer and combinatorial physical vapor deposition metal coatings (Zr, Cr, and/or Ti) deposited on a SiC f -SiC composite were investigated. Various compositions within the ternary system were corroded to the most suitable composition preventing underlying SiC f -SiC from further attack. Mass measurements and visual observations were conducted to identify which coatings formed protective oxides and which coatings spalled. Transmission electron microscopy was conducted to observe the microstructure of the physical vapor deposition metal layer before and after corrosion as well as identify the oxide which were forming.

36 MATERIALS SCIENCE↗
DOE OSTI2024

The liquid-conduction, vapor-flow heat pipe model in Sockeye

A single-phase heat pipe flow model implemented in the heat pipe application Sockeye is described. This model solves one-dimensional, compressible flow equations for the vapor phase in the center of a heat pipe, which are coupled to the two-dimensional heat conduction equation for the wick, liquid, and cladding, as well as to an ordinary differential equation tracking the working fluid inventory in the evaporator section of the heat pipe. This model is demonstrated with several test problems, including comparisons to analytic solutions for the vapor flow fields, analytic curves for sonic and capillary limitations of heat pipe operation, and some experimental data. The numerical solution gives excellent agreement for verification problems and good agreement with experimental results. Also, demonstrations show that the model is very robust, allowing for full simulations of heat pipe transients, including frozen startup, sonic-limited (supersonic) flow, and heat pipe shutdown.

42 ENGINEERING↗
DOE OSTI2024

Resonant Soft X-ray Scattering Reveals Hierarchical Structure in a Multicomponent Vapor-Deposited Glass

Multiphase vapor-deposited glasses are an important class of materials for organic electronics, particularly organic photovoltaics and thermoelectrics. These blends are frequently regarded as molecular alloys and there have been few studies of their structure at nanometer scales. Here, in this work, we show that a codeposited system of TPD (N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine) and DO37 (disperse orange 37), two small molecule glass-formers, separates into amorphous, compositionally distinct phases with a domain size and spacing ca. 10s of nanometers that depends on substrate temperature during deposition. Domains rich in one of the two components become larger and more pure at higher deposition temperatures. We use resonant soft X-ray scattering (RSoXS) complemented with atomic force microscopy (AFM) and photoinduced force microscopy to measure the phase separation, topography, and purity of the deposited films. A forward-simulation approach to RSoXS analysis, the National Institute of Standards and Technology RSoXS Simulation Suite (NIST RSoXS simulation suite), is used with models developed from AFM images to evaluate the energy dependence of scattering across multiple length scales and interpret the RSoXS with respect to structure within the films. We find that the RSoXS is sensitive to a length scale of phase separation buried within the film that is consistent with the surface composition profile, and correlates to the topography to an extent that depends on substrate temperature. We demonstrate that vacuum scattering, which is often ignored in RSoXS analysis, contributes significantly to the features and energy dependence of the RSoXS pattern, and then illustrate how to properly account for vacuum scattering to analyze films with significant roughness. We then use this analysis framework to understand structure development mechanisms that occur during vapor deposition of a TPD-DO37 codeposited glass with results that outline paths to tune morphology in multicomponent materials.

36 MATERIALS SCIENCE↗
DOE OSTI2024

On the Statistical Mechanics of Mass Accommodation at Liquid–Vapor Interfaces

Here we propose a framework for describing the dynamics associated with the adsorption of small molecules to liquid-vapor interfaces using an intermediate resolution between traditional continuum theories that are bereft of molecular detail and molecular dynamics simulations that are replete with them. In particular, we develop an effective single particle equation of motion capable of describing the physical processes that determine thermal and mass accommodation probabilities. The effective equation is parametrized with quantities that vary through space away from the liquid-vapor interface. Of particular importance in describing the early time dynamics is the spatially dependent friction, for which we propose a numerical scheme to evaluate from molecular simulation. Taken together with potentials of mean force computable with importance sampling methods, we illustrate how to compute the mass accommodation coefficient and residence time distribution. Throughout, we highlight the case of ozone adsorption in aqueous solutions and its dependence on electrolyte composition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗