Vapor Pressure Difference Research Articles

Effect of nucleation on icy pebble growth in protoplanetary discs

Solid particles in protoplanetary discs can grow by direct vapour deposition outside of ice lines. The presence of microscopic silicate particles may nevertheless hinder growth into large pebbles, since the available vapour is deposited predominantly on the small grains that dominate the total surface area. Experiments on heterogeneous ice nucleation, performed to understand ice clouds in the Martian atmosphere, show that the formation of a new ice layer on a silicate surface requires a substantially higher water vapour pressure than the deposition of water vapour on an existing ice surface. In this paper, we investigate how the difference in partial vapour pressure needed for deposition of vapour on water ice versus heterogeneous ice nucleation on silicate grains influences particle growth close to the water ice line. We developed and tested a dynamical 1D deposition and sublimation model, where we include radial drift, sedimentation, and diffusion in a turbulent protoplanetary disc. We find that vapour is deposited predominantly on already ice-covered particles, since the vapour pressure exterior of the ice line is too low for heterogeneous nucleation on bare silicate grains. Icy particles can thus grow to centimetre-sized pebbles in a narrow region around the ice line, whereas silicate particles stay dust-sized and diffuse out over the disc. The inhibition of heterogeneous ice nucleation results in a preferential region for growth into planetesimals close to the ice line where we find large icy pebbles. The suppression of heterogeneous ice nucleation on silicate grains may also be the mechanism behind some of the observed dark rings around ice lines in protoplanetary discs, as the presence of large ice pebbles outside ice lines leads to a decrease in the opacity there.

Osmolyte Depletion and Thirst Suppression Allow Hibernators to Survive for Months without Water.

Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) are obligatory hibernators who can survive over 6months of the year in underground burrows or laboratory hibernaculum without access to food or water [1]. Hibernation consists of prolonged periods of torpor, lasting up to 18days, which are characterized by low body temperature and suppressed metabolism. This torpidity is interspersed with short periods of interbout arousal, lasting up to 48 h, during which squirrels temporarily return to an active-like state and lose small amounts of water to urination and evaporation [2]. Water is also lost during torpor due to a positive vapor pressure difference created by the slightly higher temperature of the body compared to its surroundings [2, 3]. Here, we investigate the physiological mechanism of survival during prolonged water loss and deprivation throughout hibernation. By measuring hydration status during hibernation, we show that squirrels remain hydrated during torpor by depleting osmolytes from the extracellular fluid. During brief periods of arousal, serum osmolality and antidiuretic hormone levels are restored, but thirst remains suppressed. This decoupling of thirst and diuresis enables water retention by the kidney while suppressing the drive to leave the safety of the underground burrow in search of water. An acute increase in serum osmolality reinstates water-seeking behavior, demonstrating preservation of the physiological thirst circuit during hibernation. Better mechanistic understanding of internal osmolyte regulation and thirst suppression could translate to advancements in human medicine and long-term manned spaceflight. VIDEO ABSTRACT.

Drought‐Net rainfall shelters did not cause nondrought effects on photosynthesis for California central coast plants

AbstractRainfall interception shelters are frequently used to study the ecological consequences of drought. One common shelter design employs V‐shaped plastic troughs spaced on a supporting frame to intercept rainfall. Shading, reflection, and infrared radiation may alter the radiative environment under shelters in ways independent of their intended effect on soil moisture. We measured microclimate and several photosynthetic variables for watered, potted plants under rain‐out shelters and in open‐air, unsheltered plots. We tested whether the shelter infrastructure altered aboveground micrometeorology and photosynthesis for watered, potted plants of native Californian species: Elymus glaucus, Eriogonum latifolium, Mimulus aurantiacus, and Morella californica. We quantified the effects on photosynthesis in terms of light harvesting by photosystem II (PSII) and leaf‐level gas exchange on open‐air and shelter plots, the quantum yield of PSII for darkened leaves, dark respiration, and nocturnal stomatal conductance. The rain‐out shelter reduced daily integrated photosynthetically active radiation by 20%. Air temperature, leaf temperature, and leaf‐to‐air vapour pressure difference were not different under shelters compared with controls during the day. Likewise, there were no effects of shelters on net CO2 assimilation, stomatal conductance to water vapour (gs), internal leaf (CO2), or electron transport rate through PSII during the daytime. At night, Tair was 0.6°C higher under shelters, but there were no effects on dark respiration or stomatal conductance. Despite some differences in micrometeorology under rain‐out shelters compared with open‐air plots, there were little or no aboveground nondrought effects of the shelters on leaf‐level photosynthesis for watered, potted plants of these California native plant species.

Simulation of the canopy resistance of Phragmites australis in Liaohe Delta wetland, northeastern China

Abstract Evapotranspiration (ET) is the major cause of wetland water loss. The Penman–Monteith model is the most suitable ET model for wetlands. However, its accuracy depends on canopy resistance. Here, we studied the Phragmites australis community in the Liaohe Delta, northeastern China. We used flux and environmental data from the Panjin Wetland Ecosystem Research Station, and physiological and ecological parameters. Canopy resistance was calculated by the Penman–Monteith model, and canopy resistance and its influencing factors were analyzed. We created a canopy resistance model, named the Phragmites australis wetland (PW) model, using leaf stomatal resistance, leaf area index (LAI) and environmental factors. The PW model differed from the traditional Jarvis model in that the effective LAI was added, and the stomatal resistance was changed from a fixed to dynamic value and the environmental factors only contained two items: solar radiation and water vapor pressure difference. The PW model allowed the conversion from leaf scale to canopy scale. A comparison of the PW model with the Jarvis model parameters showed that accuracy improved significantly: R2 values increased from 0.56 to 0.74. The model can provide parameters for P. australis ET models and provide a new method for accurate estimation of wetland ET.

False positives from impurities result in incorrect functional characterization of receptors in chemosensory studies

The discovery of chemoreceptors and technological advances have greatly increased our understanding of chemosensory mechanisms. However, some of this rapid progress may have been severely compromised by insufficient attention given to the possible effects of impurities in the chemical standards used in identifying ligands for target receptors. Here, we show that even trace amounts of impurities in test stimuli can completely obscure true ligand-receptor relationships. Responses to impurities may go unrecognized because of two main factors. First, the sensitivity of receptors to ligands may be greater than that of the instruments used to check sample purity. Second, the concentrations of impurities actually reaching the chemoreceptor during experiments may be orders of magnitude higher than that of the putative stimulus, due to large differences in vapour pressure between the impurities and the putative stimulus. Errors caused by impurities are not limited to receptor-ligand studies, but can also affect related areas of chemosensory research, such as neural processing, downstream behaviours, and “in-silico” bioinformatics predictions of response profiles. The purity of standards is always implied but must be checked rigorously to prevent skewed or invalid results or conclusions, such as we exemplify here for Drosophila melanogaster and its olfactory receptor DmOr7a.

Development of an air drying index for lumber

Lumber is often air dried in an air drying yard prior to being placed in a dry kiln for final moisture content removal. The rate of the air drying process is dependent on local weather conditions and wood moisture content. Introduced more than 30 years ago, the Drying Index is a method to estimate the relative drying time using the difference in vapor pressures between the dry bulb and wet bulb temperatures. This paper extends its application and describes the development and use of an Air Drying Index to estimate the relative potential of a geographic location to air dry lumber based on the average monthly climate conditions for that location. The monthly Air Drying Index for 252 US locations is presented, and the annual mean for each location was used to develop an air drying map.

In situ iron coating on nanocatalysts for efficient and durable oxygen evolution reaction

The oxygen evolution reaction (OER) is essential to many important energy conversion and storage systems. To achieve high-performance and low-cost OER electrocatalysts, great effort has been devoted to the development of noble-metal-free OER nanocatalysts. While nanostructured materials have been shown effective at improving the catalytic activity, the stability of the nanocatalyst has yet to be significantly improved. Furthermore, nanocatalyst syntheses are typically complex, limiting their practical application. Herein, we design a noble-metal-free nanocatalyst which has a CoFePx core and an in situ Fe coating layer to enhance the material's catalytic activity and durability for OER. We utilize the vapor pressure difference of Fe and Co at high temperature to synthesize the CoFePx-Fe core-shell nanoparticles via a one-step high-temperature shock technique. The high-temperature method strongly anchors the CoFePx nanoparticles onto a carbon substrate. The thin Fe shell layer (~2 nm) coated on the CoFePx greatly enhances the durability of the CoFePx catalyst without hampering its activity due to the geometric effect. This nanocatalyst with an in situ Fe shell demonstrates a successful nanocoating approach for fabricating catalytically active protection layers on catalysts with improved activity and durability.

A Review of Membrane Distillation Process: Before, During and After Testing

Membrane Distillation (MD) is a promising technology for separation and purification processes. It is a thermally-driven separation process which allow only vapour molecules are to pass through a porous hydrophobic membrane. MD separation is driven by the vapour pressure difference existing between the porous hydrophobic membrane surfaces unlike normal membrane processes which operate on temperature difference. This paper focus on the expectation of MD treatment process primarily for the readers who have no idea about this membrane process A brief overview is given of MD before treatment process which includes membrane materials, membrane preparation techniques, membrane characteristics, module and configuration. Membrane performance during treatment process will be highlighted. Membrane fouling which is one of the major drawback of MD will be also discussed.

Leaf anatomical adaptations have central roles in photosynthetic acclimation to humidity.

Rates of photosynthesis can be lower in plants grown under conditions of high leaf-to-air vapour pressure difference (VPD) than under low VPD. Leaf phenotype plasticity is a primary factor determining photosynthetic responses to environmental stimuli. However, it remains unclear how changes in leaf anatomical traits drive photosynthetic acclimation to high VPD. Here, we examined the role of leaf anatomy in the differing photosynthetic responses of two tomato cultivars (Jinpeng and Zhongza) to long-term growth under high and low VPD. Photosynthesis was not affected by VPD in Jinpeng. This was attributed to homeostasis in stomatal conductance (gs) and, to a lesser extent, mesophyll conductance (gm). Disruption of synchronized changes to cell size in the epidermis and mesophyll meant that growth under high VPD reduced stomatal density in Jinpeng, but minor vein density remained unchanged. Thus, water supplied by the veins could support the increased transpirational demand, preventing stomatal closure. Variation in VPD did not affect mesophyll cell structures, and therefore gm, in Jinpeng. By contrast, photosynthesis in Zhongza was reduced under high VPD, which was primarily attributed to decreased gs and gm. The former was mainly induced by decreased stomatal aperture. Thus, transpirational demand exceeded water supply in Zhongza. This was likely due to coordinated decreases in stomatal and minor vein density driven by synchronized increases in epidermal and mesophyll cell size under high VPD. Liquid-phase limitation was primarily responsible for the reduced gm in Zhongza under high VPD. High VPD induced an increase in liquid-phase resistance by reducing the mesophyll surface area exposed to intercellular air spaces and increasing cytosolic resistance. These results suggest that plasticity in epidermal and mesophyll cell size provides an efficient means of regulating photosynthesis during acclimation to long-term high VPD.

Water evaporation rate of RSG-GAS spent fuel storage pool

Water in spent fuel storage pool that serves as a water cooling of decay heat and radiation shielding must be kept steady from evaporation. Knowledge of the evaporation rate of spent fuel storage pool is needed so that the amount of make up water can be well known for nuclear safety purposes. This study aims to calculate the rate of water evaporation in RSG-GAS spent fuel storage pool. The Shah and Carrier correlations were used to calculate the rate of evaporation based on operational data obtained in the spent fuel storage pool, i.e, pond water temperature, room temperature, relative humidity, and airflow velocity in the SFSP building. The evaporation rate calculation was performed in two conditions: during ventilation and air conditioning are operated and not operated. The calculation result shows that the rate of water evaporation rises from 0.0138 kg / m2.h to 0.0747 kg / m2.h when using Shah correlation, and from 0.0153 kg / m2.h to 0.0831 kg / m2.h when using Carrier correlation. From the calculation found that the needs of make-up water per day to replace the water loss by evaporation is 42.28 - 43.84 kg / day. The rate of evaporation of pond water during operational of ventilation air conditioning is greater than when ventilation air conditioning is not operated. The result shows that the increase of water evaporation rate of spent fuel storage pool is strongly influenced by the increase of vapor pressure difference and the length of operation time of VAC.

Mass recovery characteristics of hydrophobic hollow fiber membrane-based refrigerant mass exchangers in vapor absorption refrigeration systems

In thermally-driven vapor absorption refrigeration systems, a solution heat exchanger performs the heat recovery to elevate the thermal performance. This study focuses on the use of the hydrophobic hollow fiber membrane (HFM) for mass recovery of water vapor between two streams of lithium bromide (LiBr) solution across the HFM layers. We propose two configurations of the HFM-based refrigerant mass exchangers (HFM-RME): direct-contact and vacuum operating modes. A theoretical analysis explores the characteristics of the mass recovery processes based on simultaneous heat and mass transfer. Because the driving force of the water vapor mass recovery across the HFM layers is due to the difference in vapor pressures between the two streams of the LiBr solution, a larger temperature difference leads to higher mass recovery of the water vapor. In the direct-contact operating mode, the two streams of LiBr solution flow in direct contact across the HFM layers. The conduction heat transfer across the HFM layers reduces the solution temperatures along the length of the HFMs; as a result, it deteriorates the mass recovery of the water vapor. However, in the vacuum operating mode, the two streams of LiBr solution flow through each HFM, and the water vapor occupies the shell side at vacuum condition. The water vapor diffuses through the shell side, as the temperature difference between the LiBr solutions is given. The conduction heat transfer is neglected, and the solution temperature difference is adequately maintained along the HFM length, compared with the direct-contact operating mode. Therefore, the mass transfer of the water vapor, is enhanced by introducing the vacuum operating mode. The present work provides a comprehensive understanding of the heat and mass transfer characteristics in the proposed HFM-RMEs.

Coupled thermal transport and mass diffusion during vapor absorption into hygroscopic liquid desiccant droplets

Phase change phenomena at a droplet scale have gained extensive attention in recent years due to the unique aspects that can be exploited in a wide range of domestic and industrial applications. Different from existing studies on droplet evaporation and/or dropwise condensation, this work focuses on the mechanisms of vapor absorption into hygroscopic liquid desiccant droplets, which are of interest to many dehumidification and absorption processes. In particular we investigate the coupled heat and mass transport during vapor absorption into single droplets using optical imaging and infrared thermography. Driven by the vapor pressure difference between the ambient and the droplet surface, desiccant droplets grow due to water uptake. The droplet growth rate and final expansion ratio depend on the ambient temperature and relative humidity. After liquid desiccant droplet deposition onto the substrate, and as a consequence of the initial fast vapor absorption, droplets experience an increase in temperature. They then gradually cool down as a result of heat dissipation into the substrate and into the ambient combined with the decrease in the vapor absorption rate, i.e., heat of absorption. The temperature rise measured by infrared thermography is confirmed by the calculation of the heat of absorption for six representative environmental conditions. Furthermore the vapor pressure at the droplet surface is estimated taking account of the changes of interfacial temperature and salt concentration within the droplet bulk. As water absorbs into the droplets, the salt concentration decreases and so does the driving force for vapor diffusion and hence the heat of absorption. As a contrast, experiments with evaporating water droplets show different evolution of droplet profile, different dynamics of the triple contact line, as well as the occurrence of evaporative cooling. We conclude on the importance of taking account of the coupling mechanisms of absorptive heating and volume growth during vapor absorption into liquid desiccant droplets. Findings presented here provide a valuable extension to existing literature of phase change at the droplet scale, and contribute to a more complete understanding of the behaviors of liquid desiccant droplets in dehumidification processes.

Diffuse arc discharge with a hot cathode in a magnetic field as a plasma source of lead and silver mixture for the problem of spent nuclear fuel reprocessing

Conversion of a solid substance mixture into a low-energy (≈ 10 eV) plasma stream with stable parameters is a one of the important tasks for the developing nowadays method of plasma separation. The study of plasma stream characteristics of Pb and Ag mixture was carried out. The evaporation of the substances was realized using induction crucible heating. The discharge was initiated by an electron beam. A variation of the thermionic cathode (LaB6) temperature and the crucible heater power allowed us to control the parameters of the discharge. It was shown, that maintaining a constant potential difference in the cathode-anode gap, in spite of the substantial difference in the saturated vapor pressure of model substances, is possible due to control of the thermionic current from the cathode and constant voltage power supply parameters. Measurements of the spectral composition of plasma radiation made it possible to determine the discharge burning regimes in which ions of multiplicity 2 were absent. The obtained results indicate a possibility of using this type of discharge for testing the method of plasma separation of spent nuclear fuel.

Hydraulics Regulate Stomatal Responses to Changes in Leaf Water Status in the Fern Athyrium filix-femina.

Stomatal responses to changes in leaf water status are important for the diurnal regulation of gas exchange and the survival of plants during drought. These stomatal responses in angiosperm species are well characterized, yet in species of nonseed plants, an ongoing debate surrounds the role of metabolism, particularly the role of the hormone abscisic acid (ABA), in functionally regulating stomatal responses to changes in leaf water status. Here, we measured the stomatal response to changes in vapor pressure difference (VPD) in two natural forms of the fern species Athyrium filix-femina, recently suggested to have stomata that are regulated by ABA. The two forms measured had considerable differences in key hydraulic traits, including leaf hydraulic conductance and capacitance, as well as the kinetics of stomatal response to changes in VPD. In both forms, the stomatal responses to VPD could be accurately predicted by a dynamic, mechanistic model that assumes guard cell turgor changes in concert with leaf turgor in the light, and not via metabolic processes including the level of ABA. During drought, endogenous ABA did not play a role in stomatal closure, and exogenous ABA applied to live, intact leaves did not induce stomatal closure. Our results indicate that functional stomatal responses to changes in leaf water status in ferns are regulated by leaf hydraulics and not metabolism. With ferns being sister to seed plants, this result has implications for the evolutionary reconstruction of functional stomatal responses across vascular land plant lineages.

Vapor phase dealloying: A versatile approach for fabricating 3D porous materials

Three-dimensional porous materials with bicontinuous open porosity represent a new class of functional materials for various applications. Top-down dealloying has been demonstrated to be one of the most effective ways to fabricate 3D porous materials. Vapor phase dealloying, which makes use of the saturated vapor pressure difference between the constituent components in an alloy for selectively removing a less stable element or phase, is a promising versatile method for fabricating porous materials from active metals to inorganic elements. Here, using nickel-zinc and germanium-zinc alloys as the prototypes of single-phase and two-phase precursors, respectively, we report the fabrication of 3D bicontinuous porous Ni and Ge by vapor phase dealloying on the basis of selective element or selective phase evaporations. We also show the incorporation of vapor phase dealloying with chemical vapor deposition for the one-pot growth of 3D nanoporous graphene and the functional applications of vapor phase dealloyed porous Ge as Li ion battery electrodes. This study shines lights on the versatility of vapor phase dealloying for the fabrication of bicontinuous porous materials for a wide range of functional applications.

Temperature-regulated directional bounce of impacting droplets on gradient grooves

Droplet impact dynamics on gradient textures at room temperature have been intensively studied in the past decade. The wetting gradient surfaces are reported to direct the droplet motion. In this work, we show an undirectional rebound behavior of impacting droplets on gradient grooved surfaces at high temperature. The impinging droplet rebounds towards the denser microstructure region at contact boiling state, but towards to the sparser region when at Leidenfrost film boiling state. Our analysis indicates that the non-directional rebounding direction is attributed to the unbalanced Young's forces or vapor pressure difference between the droplet and the substrate. In contact boiling regime, the droplet rebounds towards the denser region due to the unbalanced Young's force. However, in the Leidenfrost film boiling region, adequate vapor generated underneath the droplet impedes the direct contact and larger vapor pressure in the denser region causes the droplet to rebound oppositely. This study is envisioned to promote the understanding of droplet dynamics at high temperature and provide promising applications in various systems where regulating droplet motion is needed.

Determination of human thermal comfort due to moisture permeability of clothes

PurposeThe purpose of this paper is to present the determination of human thermal comfort with wearing clothes, with different water vapor permeability. Currently, the predicted mean vote (PMV) equation is widely used to determine thermal sensation scales of human comfort. However, moisture permeability of clothes has been not taken in account where the heat is lost from a human body due to water vapor diffusion through clothes.Design/methodology/approachIn this study, the heat loss is derived based on the real structure of textiles, causing water vapor pressure difference between air on skin and ambient air. The PMV equation is modified to differentiate a thermal sensation scale of comfort although patterns of clothes are the same. Interview tests are investigated with wearing clothes from three types of textiles: knitted polyester, coated nylon–spandex, and polyurethane, under various air conditions.FindingsThe moisture permeabilities of knitted polyester, coated nylon–spandex and polyurethane are 16.57×10−9 kg/m2 s•kPa, 9.15×10−9 kg/m2•s•kPa and 2.99×10−9 kg/m2•s•kPa, respectively. The interviews reveal that most people wearing knitted-polyester clothes have the greatest cold sensations under various air conditions since moisture permeability is the highest, compared to coated nylon–spandex, and polyurethane leather. Correspondingly, the predicted results of the modified PMV equation are close to the actual mean votes of interviewees with a coefficient of determination R2=0.83. On the other hand, the coefficient of determination from the predicted results of the conventional PMV equation is significantly lower than unity, with R2=0.42.Practical implicationsIn practice, this quantitative determination on human thermal comfort gives some concrete recommendations on textile selection of clothes for acceptable satisfaction of thermal comfort under various surrounding conditions of usage.Originality/valueThe modified PMV equation effectively determines human comfort on a thermal sensation scale due to the moisture permeability of clothes. To make generic conclusion, experimental results of additional three textiles, such as plain weave/lining polyester, knitted spandex, and open structure polyester, are reported. They confirm that the modified PMV equation effectively determines human comfort on a thermal sensation scale due to the moisture permeability of clothes.

Factors controlling evaporation and the CO2 flux over an open water lake in southwest of China on multiple temporal scales

Interactions between lakes and the atmosphere are poorly understood, especially for lakes in highland areas. A better understanding of the physical processes controlling turbulent exchange dynamics over lakes is crucial to improve the numerical modelling of the lake–climate interaction. Four years of continuous measurements of energy and CO2 fluxes are conducted over a shallow highland lake (Lake Erhai) in China using eddy covariance (EC) technique from 2012 to 2015. It is found that the latent heat flux (LE) and sensible heat flux (H) has distinct diurnal and seasonal variations. The diurnal H and LE ranges from −31 to 21 W/m2 and from 31 to 171 W/m2, respectively. The heat is stored in the lake from January to June and released from July to the end of the year. The annual total evaporation of Lake Erhai varies from 1120.8 to 1228.5 mm/a, which is always higher than the annual total precipitation. On diurnal scale, the CO2 uptake is observed during most of the midday period. On an annual scale, the Lake Erhai behaves as a net CO2 source, with an annual CO2 budget ranging from 117.5 to 161.7 g C m−2 a−1. The temperature difference (ΔT) between the water surface (T s) and the air temperature (T a), and the product of ΔT and wind speed (U) are the major drivers of H from half‐hourly to monthly scale. The main factors controlling LE are U and the product of U and the vapour pressure difference (VPD) on half‐hourly and daily scales, the total cloud cover, and net radiation (R n) on the monthly scale. Photosynthetic active radiation (PAR) and U has a close relationship with half‐hourly and daily CO2 fluxes, respectively, while annual precipitation and T s has a larger effect on annual CO2 fluxes.

Flight Deployment of a High‐Resolution Time‐of‐Flight Chemical Ionization Mass Spectrometer: Observations of Reactive Halogen and Nitrogen Oxide Species

AbstractWe describe the University of Washington airborne high‐resolution time‐of‐flight chemical ionization mass spectrometer (HRToF‐CIMS) and evaluate its performance aboard the NCAR‐NSF C‐130 aircraft during the recent Wintertime INvestigation of Transport, Emissions and Reactivity (WINTER) experiment in February–March of 2015. New features include (i) a computer‐controlled dynamic pinhole that maintains constant mass flow‐rate into the instrument independent of altitude changes to minimize variations in instrument response times; (ii) continuous addition of low flow‐rate humidified ultrahigh purity nitrogen to minimize the difference in water vapor pressure, hence instrument sensitivity, between ambient and background determinations; (iii) deployment of a calibration source continuously generating isotopically labeled dinitrogen pentoxide (15N2O5) for in‐flight delivery; and (iv) frequent instrument background determinations to account for memory effects resulting from the interaction between sticky compounds and instrument surface following encounters with concentrated air parcels. The resulting improvements to precision and accuracy, along with the simultaneous acquisition of these species and the full set of their isotopologues, allow for more reliable identification, source attribution, and budget accounting, for example, by speciating the individual constituents of nocturnal reactive nitrogen oxides (NOz = ClNO2 + 2 × N2O5 + HNO3 + etc.). We report on an expanded set of species quantified using iodide‐adduct ionization such as sulfur dioxide (SO2), hydrogen chloride (HCl), and other inorganic reactive halogen species including hypochlorous acid, nitryl chloride, chlorine, nitryl bromide, bromine, and bromine chloride (HOCl, ClNO2, Cl2, BrNO2, Br2, and BrCl, respectively).

Influence of substrate temperature on incorporation of magnesium into Zn1-xMgxO layers growth by molecular beam epitaxy

Plasma-assisted molecular beam epitaxy growth of ZnO and Zn1-xMgxO epilayers on Al2O3 (11–20) substrates is described. The influence of the substrate temperature on the growth rate and magnesium concentration in Zn1-xMgxO epilayers was studied in detail. It was found that the composition of magnesium in Zn1-xMgxO epilayers increased with increasing substrate temperature. The composition variation in the alloys as a function of the growth temperature could be explained by the difference of vapor pressure of Mg and Zn at high growth temperature. Theoretical approaches to surface evaporation of metal atoms under different growth condition are difficult. Here, we describe an uncomplicated method determine quantities experimental to obtain. These results can be extended to other types of ternary or quaternary materials grown by MBE technique.