Gas Phase Equilibrium Research Articles

Solid-to-gas phase transition kinetics of diverse potassium occurrence forms during biomass pellet combustion: Time-resolved detection and multi-step modeling

The solid-to-gas phase transition of potassium during biomass combustion significantly impacts ash-related issues in bioenergy systems, affecting operational efficiency and equipment longevity. However, the specific mechanisms and kinetics of this transition process remain inadequately understood. This work investigates the time-resolved transition of solid-phase potassium to the gas phase during the combustion of rice husk and wheat straw pellets, combining experimental measurements with theoretical modeling. Tunable diode laser absorption spectroscopy (TDLAS) was employed to measure atomic potassium concentrations 15 mm above burning pellets tray, where gas-phase equilibrium is approached. Key combustion characteristics including thermogravimetric profiles, spectral radiation, and temperature were simultaneously monitored. A novel multi-step model was developed to describe the transition of different forms of solid-phase potassium (organic, exchangeable, and inorganic) to the gas phase. This model integrates TDLAS measurements, observed combustion characteristics, and biomass physicochemical properties. Thermodynamic equilibrium calculations were used to estimate the atomic potassium fraction from total gaseous potassium. The results showed that the solid-to-gas phase transition of organic potassium synchronizes with volatiles release. In contrast, the maximum emission rates of inorganic and exchangeable potassium occurred at the onset of char combustion. The developed model agrees well with the online detection experiments and were further validated by offline ICP analysis of residual ash. While not directly simulating gas-solid interface reactions near the particle surface, this work lays groundwork for future multi-scale modeling of particle-laden flows and reactor-scale phenomena in biomass combustion systems.

Understanding shape selectivity effects of hydroisomerization using a reaction equilibrium model.

We study important aspects of shape selectivity effects of zeolites for hydroisomerization of linear alkanes, which produces a myriad of isomers, particularly for long chain hydrocarbons. To investigate the conditions for achieving an optimal yield of branched hydrocarbons, it is important to understand the role of chemical equilibrium in these reversible reactions. We conduct an extensive analysis of shape selectivity effects of different zeolites for the hydroisomerization of C7 and C8 isomers at chemical reaction equilibrium conditions. The reaction ensemble Monte Carlo method, coupled with grand-canonical Monte Carlo simulations, is commonly used for computing reaction equilibrium of heterogeneous reactions. The computational demands become prohibitive for a large number of reactions. We used a faster alternative in which reaction equilibrium is obtained by imposing chemical equilibrium in the gas phase and phase equilibrium between the gas phase components and the adsorbed phase counterparts. This effectively mimics the chemical equilibrium distribution in the adsorbed phase. Using Henry's law at infinite dilution and mixture adsorption isotherm models at elevated pressures, we calculate the adsorbed loadings in the zeolites. This study shows that zeolites with cage or channel-like structures exhibit significant differences in selectivity for alkane isomers. We also observe a minimal impact of pressure on the gas-phase equilibrium of these reactions at typical experimental reaction temperatures 400-700K. This study marks initial strides in understanding the reaction product distribution for long-chain alkanes.

Coupled dynamic modeling of scrap melting and gas phase reactions in the electric arc furnace process

Gas phase reactions have a significant effect on the composition and heat content of the off-gas in the electric arc furnace (EAF) process. In this work, a previously developed dynamic scrap melting and heat transfer model was coupled with a gas phase reaction module based on Gibbs energy minimization. The gas phase reaction module retrieves the necessary thermodynamic data from a previously developed thermochemistry module. The gas phase reaction module has been used to improve the description of the gas burners and the freeboard of the EAF. The implementation of the gas phase reaction module has been found to be in good agreement with commercially available software (HSC Sim) for calculations assuming a gas phase equilibrium.

Methoxyacetone revisited

Conformational space of methoxyacetone (MA) was studied at the MP2/6–311++G(d,p) and DFT(B3LYP)/6–311++G(d,p) levels of theory. Computations predict MA to adopt four conformations, resulting from internal rotations around the O=C−C−O (Trans, Cis) and C−C−O−C (trans, gauche) dihedral angles. The Tt (Trans-trans) conformer is the most stable. The computed energies of two gauche (Tg and Cg) conformers fall in the 3–8 kJ mol−1 range above Tt and should account for 1/3 of the room-temperature gas-phase equilibrium. The energy of Ct form is 11 kJ mol−1 above Tt, and its expected population is negligible (below 1 %). In our earlier work, MA monomers were isolated in cryogenic argon matrices and characterized by infrared spectroscopy. In the experiment, only the most stable Tt conformer was detected in the sample. Signatures of the other conformers were not detected, either in freshly deposited samples, or in samples subjected to different UV irradiations. We rationalize those observations in terms of computed barriers for intramolecular torsions, indicating occurrence of conformational cooling during deposition. The experimental infrared spectrum of the Tt form is now assigned with the aid of anharmonic DFT computations. Exposure of MA to UV irradiation in the 300–260 nm range led to photolysis, according to the Norrish type II mechanism, resulting in dimer between enol acetone and formaldehyde observed as a cage-confined intermediate photoproduct. The subsequent photolysis resulted in the formation of carbon monoxide as the dominating photoproduct, formed in the Norrish type I photoreaction. Mechanistic interpretation of this photo decarbonylation reaction is presented.

Determination of Kinetic Parameters and Identification of the Rate-Determining Steps in the Oxygen Exchange Process for LaNi0.6Fe0.4O3-δ.

The mixed ionic and electronic oxide LaNi0.6Fe0.4O3-δ (LNF) is a promising ceramic cathode material for solid oxide fuel cells. Since the reaction rate of oxygen interaction with the cathode material is extremely important, the present work considers the oxygen exchange mechanism between O2 and LNF oxide. The kinetic dependence of the oxygen/oxide interaction has been determined by two isotopic methods using 18O-labelled oxygen. The application of the isotope exchange with the gas phase equilibrium (IE-GPE) and the pulsed isotope exchange (PIE) has provided information over a wide range of temperatures (350-800 °C) and oxygen pressures (10-200 mbar), as each method has different applicability limits. Applying mathematical models to treat the kinetic relationships, the oxygen exchange rate (rH, atom × cm-2 × s-1) and the diffusion coefficient (D, cm2/s) were calculated. The values of rH and D depend on both temperature and oxygen pressure. The activation energy of the surface exchange rate is 0.73 ± 0.05 eV for the PIE method at 200 mbar, and 0.48 ± 0.02 eV for the IE-GPE method at 10-20 mbar; for the diffusion coefficient, the activation energy equals 0.62 ± 0.01 eV at 10-20 mbar for the IE-GPE method. Differences in the mechanism of oxygen exchange and diffusion on dense and powder samples are observed due to the different microstructure and surface morphology of the samples. The influence of oxygen pressure on the ratio of contributions of different exchange types to the total oxygen exchange rate is demonstrated. For the first time, the rate-determining step in the oxygen exchange process for LNF material has been identified. This paper discusses the reasons for the difference in the mechanisms of oxygen exchange and diffusion.

Triethylamine borane thermal decomposition for BN low pressure chemical vapour deposition

Triethylamine borane (TEAB) complex was studied as a potential precursor for the thermal low pressure chemical vapour deposition (LPCVD) of pure crystalline sp2-hybridised BN. In particular, its thermal decomposition with or without ammonia was characterised from thermodynamic and experimental points of view in the temperature ranges 400–2000 °C and 300–1300 °C, respectively. NH3 plays a role in the gas phase equilibrium by providing a nitriding source that promotes HCN formation at high temperatures. NH3 is also a source of hydrogen for light hydrocarbons formation as it decomposes. It is thus possible to promote gaseous carbon species formation at high temperatures and limit carbon introduction into coatings by adding ammonia. A turbostratic BN coating could be obtained by CVD from a TEAB/NH3/N2 mixture and conditions chosen thanks to the gas phase decomposition study.

Thermodynamic characterization of interactions between environmental contaminants and room temperature ionic liquids using static headspace gas chromatography with vacuum ultraviolet detection

Understanding the thermodynamic interactions between an analyte and the sample phase is of paramount importance when choosing a co-solvent in headspace analysis. A sample phase – gas phase equilibrium partition coefficient (Kp) is used fundamentally to describe the distribution of the analyte between the two phases. Kp determinations by headspace gas chromatography (HS-GC) were acquired by two methods: vapor phase calibration (VPC) and phase ratio variation (PRV). Here, we demonstrated a pressurized – loop headspace system in conjunction with gas chromatography vacuum ultraviolet detection (HS-GC-VUV) to directly calculate the concentration of analytes in the gas phase from room temperature ionic liquids (RTILs) sample phases, using pseudo-absolute quantification (PAQ). PAQ, an attribute of VUV detection, allowed for quick determination of Kp and other thermodynamic properties, such as enthalpy (ΔH) and entropy (ΔS) of the system through the use of van't Hoff plots in the temperature range of 70–110 °C. The Kp determinations by PAQ were comparable to those obtained using the VPC method with percent difference ranging from ≤ 1–33%. Kp determinations were made for analytes (cyclohexane, benzene, octane, toluene, chlorobenzene, ethylbenzene, m-,p-, and o-xylene) at the varying temperatures (70–110 °C) using different RTILs (1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][ESO4]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and tris(2-hydroxyethyl)methylammonium methylsulfate ([MTEOA][MeOSO3])) and (1-ethyl-3-methylimidazolium bis(trisfluoromethanesulfonyl)imide ([EMIM] [NTF2])). The results from the van't Hoff analysis revealed that [EMIM] cation-based RTILs exhibit strong solute-solvent interactions with analytes that have π- electrons.

Structural study of some unsaturated malononitriles using mass spectrometry and theoretical models

AbstractThe study of tautomerism has gained relevance in the scientific community because several cellular processes occur through different tautomeric forms of certain compounds. The percentage of each tautomer in compounds with tautomerism capability depends on numerous factors, such as temperature and solvent polarity, among others; and, by changing the external conditions, equilibrium displacement can be established very quickly. This manuscript deals with nitrile–ketenimine tautomerism in some unsaturated malononitriles. This kind of compounds with two nitrile groups conjugated to a double bound is able to rearrange accessible hydrogens and provide new and complex structures of different functionalities. The authors' motivation for investigating these compounds lies in understanding their tautomeric behavior in solution and gas phases and to predict reaction deportment to then account for the final products obtained. Four unsaturated malononitriles were synthesized to study the substituent effect on equilibrium displacement. Characterization was performed using nuclear magnetic resonance (NMR) and tautomeric equilibrium in gas phase was evaluated by mass spectrometry. Correlation with theoretical calculations was carried out in order to comprehend the system behavior.

Predicting the fate and transport of indoor DEHP considering their interaction with particles under different ventilation modes

Ventilation are widely used in residential buildings to dilute indoor pollutants. While the dynamic partition model of semi-volatile organic compounds (SVOCs) for homes with a central forced-air handling system is still far from adequate. Here we developed a mechanistic model of SVOCs considering dynamic behaviours of size-resolved particles brought by ventilation. In this model, effects of air changes per hour (ACH) and secondary source of particles on mass transfer coefficient of source surfaces (hms) are considered. Three factors, namely ventilation mode, fresh air ratio and filtration efficiency are examined in detail, to figure out the time-varying multi-phase concentration of di-2-ethylhexyl phthalate (DEHP). Results show that with identical ACH (total ventilation rate/volume), the increase of indoor-outdoor air exchange rate (AER_I/O), would decrease the gas-phase concentration of DEHP, and would significantly shorten the time for the multi-phase DEHP to reach equilibrium concentration. The multi-phase (including the gas-phase, particle-phase and dust-phase) equilibrium concentration of DEHP indoors decreases with the increased fresh air ratio, taking into account the combined effect of ventilation dilution and particle-enhanced source emission. With the increase of filtration efficiency, the particle-phase equilibrium concentration of DEHP decreases, while the gas-phase equilibrium concentration of DEHP increases. Overall, the dynamic model is helpful to improve understandings of SVOCs’ interactions with airborne particles caused by ventilation systems, and clarify the key ventilation factors affecting the time-varying multi-phase concentration of SVOCs.

The Deep Atmospheric Composition of Jupiter from Thermochemical Calculations Based on Galileo and Juno Data

The deep atmosphere of Jupiter is obscured beneath thick clouds. This causes direct observations to be difficult, and thermochemical equilibrium models fill in the observational gaps. This research uses Galileo and Juno data together with the Gibbs free energy minimization code GGchem to update the gas phase and condensation equilibrium chemistry of the deep atmosphere of Jupiter down to 1000 bars. Specifically, the Galileo data provides helium abundances and, with the incorporated Juno data, we use new enrichment values for oxygen, nitrogen, carbon and sulphur. The temperature profile in Jupiter’s deep atmosphere is obtained following recent interior model calculations that fit the gravitational harmonics measured by Juno. Following this approach, we produced pressure–mixing ratio plots for H, He, C, N, O, Na, Mg, Si, P, S and K that give a complete chemical model of all species occurring to abundances down to a 10−20 mixing ratio. The influence of the increased elemental abundances can be directly seen in the concentration of the dominant carriers for each element: the mixing ratio of NH3 increased by a factor of 1.55 as compared with the previous literature, N2 by 5.89, H2O by 1.78, CH4 by 2.82 and H2S by 2.69. We investigate the influence of water enrichment values observed by Juno on these models and find that no liquid water clouds form at the oxygen enrichment measured by Galileo, EH2O = 0.47, while they do form at higher water abundance as measured by Juno. We update the mixing ratios of important gas phase species, such as NH3, H2O, CO, CH4 and H2S, and find that new gas phase species, such as CN−, (NaCN)2, S2O and K+, and new condensates, namely H3PO4 (s), LiCl (s), KCl (s), NaCl (s), NaF (s), MgO (s), Fe (s) and MnS (s), form in the atmosphere.

Noninvasive Detection of Bacterial Infection in Children Using Piezoelectric E-Nose.

Currently, antibiotics are often prescribed to children without reason due to the inability to quickly establish the presence of a bacterial etiology of the disease. One way to obtain additional diagnostic information quickly is to study the volatile metabolome of biosamples using arrays of sensors. The goal of this work was to assess the possibility of using an array of chemical sensors with various sensitive coatings to determine the presence of a bacterial infection in children by analyzing the equilibrium gas phase (EGP) of urine samples. The EGP of 90 urine samples from children with and without a bacterial infection (urinary tract infection, soft tissue infection) was studied on the "MAG-8" device with seven piezoelectric sensors in a hospital. General urine analysis with sediment microscopy was performed using a Uriscan Pro analyzer and using an Olympus CX31 microscope. After surgical removal of the source of inflammation, the microbiological studies of the biomaterial were performed to determine the presence and type of the pathogen. The most informative output data of an array of sensors have been established for diagnosing bacterial pathology. Regression models were built to predict the presence of a bacterial infection in children with an error of no more than 15%. An indicator of infection is proposed to predict the presence of a bacterial infection in children with a high sensitivity of 96%.

Improving Condensed-Phase Water Dynamics with Explicit Nuclear Quantum Effects: The Polarizable Q-AMOEBA Force Field.

We introduce a new parametrization of the AMOEBA polarizable force field for water denoted Q-AMOEBA, for use in simulations that explicitly account for nuclear quantum effects (NQEs). This study is made possible thanks to the recently introduced adaptive Quantum Thermal Bath (adQTB) simulation technique which computational cost is comparable to classical molecular dynamics. The flexible Q-AMOEBA model conserves the initial AMOEBA functional form, with an intermolecular potential including an atomic multipole description of electrostatic interactions (up to quadrupole), a polarization contribution based on the Thole interaction model and a buffered 14-7 potential to model van der Waals interactions. It has been obtained by using a ForceBalance fitting strategy including high-level quantum chemistry reference energies and selected condensed-phase properties targets. The final Q-AMOEBA model is shown to accurately reproduce both gas-phase and condensed-phase properties, notably improving the original AMOEBA water model. This development allows the fine study of NQEs on water liquid phase properties such as the average H-O-H angle compared to its gas-phase equilibrium value, isotope effects, and so on. Q-AMOEBA also provides improved infrared spectroscopy prediction capabilities compared to AMOEBA03. Overall, we show that the impact of NQEs depends on the underlying model functional form and on the associated strength of hydrogen bonds. Since adQTB simulations can be performed at near classical computational cost using the Tinker-HP package, Q-AMOEBA can be extended to organic molecules, proteins, and nucleic acids opening the possibility for the large-scale study of the importance of NQEs in biophysics.

Structure, conformational landscape and UV-induced selective rotamerization of 2-aminoacetanilide

The molecular structure, conformational space and UV-induced rotamerization and decarbonylation of 2-aminoacetanilide (2AA) were investigated by matrix isolation infrared spectroscopy and quantum chemical electronic structure calculations. The compound was isolated in a cryogenic (15 K) argon matrix, and four conformers were spectroscopically identified: two trans-amide (OCNH dihedral ∼ 180°) conformers (trans-I and trans-II), and two higher-energy cis-amide (OCNH dihedral ∼ 0°) conformers (cis-I and cis-II). These four conformers were found to be present in the as-deposited matrix of 2AA in a population ratio matching well that predicted by the calculations for the gas-phase equilibrium at the temperature of the vapor of the compound before deposition (60 °C = 333.15 K). The calculations predicted also the existence of an additional higher-energy trans-amide conformer (trans-III) which was not observed experimentally. In situ broadband UV irradiation (λ > 235 nm) of the matrix-isolated compound was found to induce selective conversion of conformer trans-I into conformer trans-II, in a few minutes (55 % after 2 min. of irradiation; 70 % after 10 min.), while the populations of the cis-amide conformers did not change. Prolonged UV irradiation was found to result in decomposition of the compound, leading to generation of carbon monoxide and 2-amine-N-methylaniline. The infrared spectra of the experimentally relevant conformers of 2AA were interpreted and assigned with help of normal coordinate analysis, and the different behavior of the conformers of 2AA upon UV-irradiation of the argon matrix was explained with help of time-dependent DFT (TD-DFT) calculations.

Protomer Formation Can Aid the Structural Identification of Caffeine Metabolites.

The structural annotation of isomeric metabolites remains a key challenge in untargeted electrospray ionization/high-resolution mass spectrometry (ESI/HRMS) metabolomic analysis. Many metabolites are polyfunctional compounds that may form protomers in electrospray ionization sources and therefore yield multiple peaks in ion mobility spectra. Protomer formation is strongly structure-specific. Here, we explore the possibility of using protomer formation for structural elucidation in metabolomics on the example of caffeine, its eight metabolites, and structurally related compounds. It is observed that two-thirds of the studied compounds formed high- and low-mobility species in high-resolution ion mobility. Structures in which proton hopping was hindered by a methyl group at the purine ring nitrogen (position 3) yielded structure-indicative fragments with collision-induced dissociation (CID) for high- and low-mobility ions. For compounds where such a methyl group was not present, a gas-phase equilibrium could be observed for tautomeric species with two-dimensional ion mobility. We show that the protomer formation and the gas-phase properties of the protomers can be related to the structure of caffeine metabolites and facilitate the identification of the structural isomers.

Round-Robin Measurement of Surface Tension for Liquid Titanium by Electromagnetic Levitation (EML) and Electrostatic Levitation (ESL)

To accurately measure the surface tension of liquid titanium free of contamination from chemical reaction with the supporting materials and dissolution of atmospheric oxygen, the measurement was performed by using electromagnetic levitation (EML) and electrostatic levitation (ESL) in consideration of the influence of oxygen partial pressure of the measurement atmosphere, PO2. When liquid titanium was maintained at 2000 K under Ar–He gas with PO2 of 10 Pa flowing at 2 L·min−1 using EML, the surface tension decreased with time due to the dissolution of atmospheric oxygen into the sample. When the PO2 of the gas was decreased to 10−2 Pa, the oxygen content and the surface tension were confirmed to not vary, even after 120 min. Even though PO2 further decreased to 10−11 Pa under Ar–He–H2 gas, the surface tension slightly increased with time due to gas phase equilibrium between H2 and H2O that allowed for a continuous dissolution of atmospheric oxygen into the liquid titanium. The surface tension of liquid titanium measured by ESL, which prevents contamination of the sample from supporting materials and the high 10−5 Pa vacuum inhibits the dissolution of oxygen, showed almost the same value as that measured under Ar–He gas at PO2 of 10−2 Pa by EML. From the measurement results of EML and ESL, the surface tension of the 99.98 mass % pure liquid titanium, free from any contaminations from chemical reactions, with the supporting material and dissolved oxygen was expressed as σ99.98%=1613−0.2049T−1941 (10−3 N·m−1).

Comment on "Microhydration of Biomolecules: Revealing the Native Structures by Cold Ion IR Spectroscopy".

This Viewpoint presents a re-examination of the conclusions of a study reported in The Journal of Physical Chemistry Letters (Saparbaev, et al. 2021, 12, 907) that compared the structure of microsolvated ions formed by electrospray ionization to those formed in the gas-phase via a previously published cryogenic ion trap approach. We conducted additional experiments that clearly show that most of the observed differences in the IR spectra can be accounted for by considering the different spectroscopic action schemes used to obtain them. In particular, the presence of the D2-tag induces shifts in some of the N-H and O-H peaks which need to be carefully considered before comparing spectra. Once these spectral effects are taken into account, we show that both clustering approaches yield similar cluster structures for the small GlyH+(H2O)n species. Using unimolecular reaction rate theory, we also show that for the small complexes considered here, only the gas-phase equilibrium distribution of conformers should be expected in both experimental approaches. In addition, the barrier heights necessary to kinetically trap high-energy conformers at 298 K is explored using a series of model polyalanine chains.

Key Role of Equilibrium HONO Concentration over Soil in Quantifying Soil-Atmosphere HONO Fluxes.

Nitrous acid (HONO) is an important component of the global nitrogen cycle and can regulate the atmospheric oxidative capacity. Soil is an important source of HONO. [HONO]*, the equilibrium gas-phase concentration over the aqueous solution of nitrous acid in the soil, has been suggested as a key parameter for quantifying soil fluxes of HONO. However, [HONO]* has not yet been well-validated and quantified. Here, we present a method to retrieve [HONO]* by conducting controlled dynamic chamber experiments with soil samples applied with different HONO concentrations at the chamber inlet. We show a bi-directional soil–atmosphere exchange of HONO and confirm the existence of [HONO]* over soil: when [HONO]* is higher than the atmospheric HONO concentration, HONO will be released from soil; otherwise, HONO will be deposited. We demonstrate that [HONO]* is a soil characteristic, which is independent of HONO concentrations in the chamber but varies with different soil water contents. We illustrate the robustness of using [HONO]* for quantifying soil fluxes of HONO, whereas the laboratory-determined chamber HONO fluxes can largely deviate from those in the real world for the same soil sample. This work advances the understanding of the soil–atmosphere exchange of HONO and the evaluation of its impact on the atmospheric oxidizing capacity.

The dynamic partitioning of airborne phthalates in indoor environment: effects of ventilation

Low energy consumption buildings with strong air tightness such as passive buildings are the development trend in the world. However, ventilation directly affects the emission and dynamic transport of indoor phthalates. A transient partition model considering the dynamic behavior of size-resolved particle was utilized to investigate the influence of ventilation on the airborne Di-2-ethylhexyl phthalate (DEHP). The air exchange rate (a) was set to 0.15 h-1, 0.3 h-1, 0.6 h-1, 2h-1 for the different conditions. The predicted gas-phase concentration of DEHP in the initial 70 days is unaffected for different a and constant hms, whereas it raises until the a increases to 2 h-1. The equilibrium gas-phase concentration decreases from 0.257 to 0.203 μg/m3. Meanwhile, the higher a also reduced the particle-phase concentration of DEHP. Furthermore, the changes of airborne DEHP were analyzed by considering the impact of a on hms caused by ventilation. The results indicates that more ventilation leads to higher gas-phase concentration for the whole stage. The gas-phase concentration at equilibrium increases from 0.237 to 0.440 μg/m3. The total airborne (gas-phase + particle-phase) concentration decreases with the higher ventitation rate, which indicates that the ventitation has a positive effect on indoor airborne DEHP.

Atomic layer deposition of lithium metaphosphate from H3PO4 and P4O10 facilitated via direct liquid injection: Experiment and theory

We report the use of H3PO4 as a reactant in atomic layer deposition (ALD) of lithium metaphosphate. The ALD growth cycle starts by injection of the lithium tetramethyl heptadionate (LiTMHD) precursor followed by injection of the H3PO4 reactant. Both the reactant and the precursor are injected into the ALD chamber via direct liquid injection, which allows us to achieve ALD without plasma or high temperatures. The liquid H3PO4 solution, injected 10 s after the precursor, evaporates and decomposes into the gaseous mixture of H3PO4, P4O10, and H2O. The H3PO4 and P4O10 molecules finally react with the LiTMHD molecules adsorbed at the sample substrate, which results in the film growth. The obtained films are amorphous, and the x-ray photoelectron spectroscopy measurements reveal the LiPO3 composition. The growth process exhibits the features of the ALD, namely, the saturation of the growth rate with cycle duration and the maximum growth rate when the number of the injected precursor/reactant molecules reaches a critical value. We show theoretically that the growth rate is governed by the gas-phase equilibrium between H3PO4 and P4O10, both of which are reactive but to different degrees. Depending on the temperature and other conditions, we obtain a reactive gas adjustable at will between pure H3PO4 and pure P4O10. Our theory explains essential features of the observed ALD growth. It determines which of the two reactants (H3PO4 or P4O10) causes the growth and which of them provides a faster growth.

Thermodynamics of equilibrium alkali plasma. Simple and accurate analytical model for non-trivial case

Analytical equation of state for pure alkali metals (lithium, sodium, potassium, rubidium and cesium) in equilibrium gas phase is proposed. This equation has a simple form, generalizes the equation of state for a perfect gas and is universal for all alkali elements. It correctly reproduces the experimental data for the equilibrium gas phase over a wide range of pressures (up to ∼105 Pa) and temperatures (up to ∼3⋅103 K). On the basis of this equation of state, expressions for thermal and caloric coefficients as well as for other physical characteristics are obtained. The results of this study confirm feasibility of the principle of corresponding states in relation to the group of alkali elements.