Condensation Of Supersaturated Vapor Research Articles

On the time decay of the photoinduced condensation in supersaturated vapors

Calculations are carried out to solve the thus far puzzling problem of the long-time trends in the photoinduced condensation of supersaturated vapors observed in thermal diffusion cloud chambers. These trends are the long-time delay of the condensation after switching the light on and the long-time decay after terminating the light. The calculations show that the supersaturation level which governs the condensation process cannot be affected significantly by irradiation under conventional experimental circumstances, and hence its change cannot be the cause of the long-time transients. These trends are attributed to the slow diffusion-limited growth of liquid droplets before they achieve the observable size of 10−3–10−2 cm. The predictions are in good agreement with experimental data.

Condensation of Supersaturated Vapors on Benzene Ions Generated by Resonant Two-Photon Ionization: A New Technique for Ion Nucleation

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCondensation of Supersaturated Vapors on Benzene Ions Generated by Resonant Two-Photon Ionization: A New Technique for Ion NucleationDavid Kane, George M. Daly, and M. Samy El-ShallCite this: J. Phys. Chem. 1995, 99, 20, 7867–7870Publication Date (Print):May 1, 1995Publication History Published online1 May 2002Published inissue 1 May 1995https://doi.org/10.1021/j100020a006RIGHTS & PERMISSIONSArticle Views105Altmetric-Citations47LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (445 KB) Get e-Alerts

Condensation of Supersaturated Vapors of Dioctylphthalate: Homogeneous Nucleation Rate Measurements

Homogeneous nucleation rates of dioctylphthalate (DOP) [1,2-benzenedicarboxylic acid (bis-2-ethyl hexyl ester)] ranging from 0.032 to 16.3 drops cm−3 s−1 were measured as a function of supersaturation and temperature by using an upward thermal diffusion cloud chamber. The influence of thermodiffusiophoresis was included in raw data analysis. An empirical formula was used to fit measured nucleation rates over a supersaturation range from 33 to 68 and temperatures ranging from 364 to 396 K. A comparison with earlier published data on critical supersaturations of DOP showed consistency of both measurements.

Condensation of supersaturated vapors. Homogeneous nucleation of bis(2-ethyl-hexyl)sebacate (DEHS)

A thermal diffusion cloud chamber was used to measure the critical supersaturations of bis(2-ethyl-hexyl)sebacate (DEHS) required for a rate of homogeneous nucleation of about 5 drops cm −3 s −1. The experiments were carried out in the 370–440 K temperature range with hydrogen and helium as inert gases.

Condensation of Supersaturated Vapors: Homogeneous Nucleation of Dioctylphthalate (DOP)

Upward and downward thermal diffusion cloud chambers were used to measure the critical supersaturations of dioctylphthalate (DOP) [1, 2-benzenedicarboxylic acid (bis-2-ethyl hexyl ester)] that were required for a rate of homogeneous nucleation of about 5 drops cm−3s−1. The results were compared with the predictions of the classical (Volmer-Becker-Döring-Zeldovitch) theory and the Lothe-Pound theory of homogeneous nucleation. At 293° K the classical theory overestimates the experiment by a factor of about 12 and Lothe-Pound theory underestimates it by a factor of about 0.3.

Kinetics of isothermal homogeneous-condensation processes

Isothermal condensation of supersaturated vapors of various substances and formation of lampblack particles by isothermal decomposition of hydrocarbon (acetylene) molecules is investigated by analytic methods. Expressions that differ generally from the classical ones are obtained, on the basis of the quasichemical model of cluster particles, for the quasi-equilibrium and stationary distribution functions of the cluster sizes, as well as for the rates of formation of clusters having critical dimensions. Analytic expressions describing the time evolution of the degree of supersaturation and of the size distribution function of condensed cluster particles are obtained for the case when the system goes over from the supersaturated state to thermodynamic equilibrium. Equations for the principal characteristics of lampblack formation, viz., the characteristic time and the average size and density of the lampblack particles, are obtained with allowance for the properties of the formation and dissociation (evaporation) of small lampblack cluster particles.

Condensation of supersaturated vapours. Homogeneous nucleation of naphthalene and phthalic anhydride

The critical supersaturation required for the homogeneous nucleation of naphthalene and phthalic anhydride from their vapours has been measured using upward thermal diffusion cloud chamber. The results obtained are compared with the predictions of the classical theory of homogeneous nucleation (Volmer-Becker-Doring-Zeldovich) and the corresponding states correlation of homogeneous nucleation. The classical theory is found to be in excellent agreement with the experimental results on naphthalene but overpredicts the critical supersaturation of phthalic anhydride vapours by about 30%. In order to fit the experiment and theory, the new values of surface tension of phthalic anhydride were recalculated from the theory. Critical supersaturation of naphthalene plotted versus temperature reveals the same regular departure from single fluid behaviour as found for alkylbenzenes. The experimental results on phthalic anhydride were found to be in very good agreement with the corresponding states correlation.

Condensation of supersaturated vapours in the downward and upward thermal diffusion cloud chamber. Homogeneous nucleation of stearic acid

The function of the thermal diffusion cloud chamber in the downward regime was verified on the basis of comparison of the “downward” and “upward” critical supersaturation of vapours of stearic acid. It has been verified experimentally that in the downward thermal diffusion cloud chamber it is possible to reduce substantially the effect of phoretic forces by increasing the pressure of inert gas. Thus the thermal diffusion cloud chamber in the downward regime is suitable for studies of nucleation in vapours of low volatile compounds.

Generation and characterization of submicron aerosols of zinc oxide

An apparatus has been developed to produce submicron aerosols of zinc oxide by the condensation of supersaturated vapors in a tube furnace. The mass concentration and the size distribution of the aerosols were stable over a period of several hours. Various particle morphologies (chain aggregates, large blocky particles and fine spiked particles) were produced by varying the operating conditions. According to analyses of electron micrographs, the primary particle diameters obeyed a log-normal distribution with count median diameters between 0.008 and 0.040 µm with geometric standard deviations from 1.42 to 1.67.

Generation and characterization of submicron aerosols of zinc oxide

An apparatus has been developed to produce submicron aerosols of zinc oxide by the condensation of supersaturated vapors in a tube furnace. The mass concentration and the size distribution of the aerosols were stable over a period of several hours. Various particle morphologies (chain aggregates, large blocky particles and fine spiked particles) were produced by varying the operating conditions. According to analyses of electron micrographs, the primary particle diameters obeyed a log-normal distribution with count median diameters between 0.008 and 0.040 µm with geometric standard deviations from 1.42 to 1.67.

Changes in lung volumes and diffusing capacity in guinea pigs exposed to a combination of sulfur dioxide and submicron zinc oxide mixed in a humidified furnace

Male Charles River Hartley guinea pigs were exposed for 3 hr to zinc oxide (ZnO) aerosols alone (7.8 mg/m 3) and to various concentrations of ZnO (0.8, 2.7, or 6.0 mg/m 3) in combination with sulfur dioxide (SO 2). The ZnO aerosols ( CMD 0.05 μm, σg 2.0) were generated by the condensation of supersaturated vapors and mixed with SO 2 in a water vapor-saturated furnace at 480°C. We evaluated ventilation, lung mechanics, lung volumes, diffusing capacity for carbon monoxide ( DL CO), and alveolar volume ( VA) in anesthetized, tracheostomized animals after exposure to the aerosols. Breathing frequency, tidal volume, and pulmonary resistance and compliance were unchanged in all exposed groups. Exposure of animals to ZnO alone resulted in significant decrease in functional residual capacity ( FRC) with only minimal changes in other lung volume subdivisions, DL CO and VA. A dose response was induced in animals exposed to SO 2 and increasing concentrations of ZnO as shown by decreases in lung volumes, DL CO and VA. In animals exposed to the lowest ZnO concentration (0.8 mg/m 3), vital capacity ( VC) was significantly lower while other lung volume parameters, DL CO and VA, were unchanged compared to control values. As the concentration of ZnO was increased, as in the 6.0 mg/m 3 ZnO group, all lung volume subdivisions, DL CO and VA, were significantly decreased. Analysis of collected aerosols during the experiments indicated the presence of sulfate, sulfite, and adsorbed sulfur trioxide, all of which could induce bronchoconstriction in the guinea pig. The nature of the response in this study suggests a reaction in the periphery of the lungs indicating that the various sulfur species were carried into the lung parenchyma by the submicron ZnO particles. The decreased lung volumes, DL CO and VA, indicate alveolar duct constriction probably with the involvement of pulmonary edema.

Condensation of supersaturated vapours of solid and liquid benzophenone in the diffusion cloud chamber

Condensation of supersaturated vapours of solid and liquid benzophenone in the diffusion cloud chamber

Condensation of supersaturated vapours of α- and β-naphtholes in the diffusion cloud chamber

Condensation of supersaturated vapours of α- and β-naphtholes in the diffusion cloud chamber

Nucleation in bubble chambers

A new approach is presented to the creation of vapour bubbles in superheated liquids by high ebergy charged particles. A compilation is given of the theoretical work done on both spontaneous nucleation and nucleation under the influence of charged particles. The processes are compared with another nucleation process, the condensation of supersaturated vapours. Some striking differences are demonstrated. It is seen to be plausible that nucleation in liquids through the action of charged particles is a thermal process, for which the liquid must be heated locally. The amount of heat necessary to create a bubble that can grow to visible size has been calculated for a number of practical cases. The energies are 8.2 eV for helium, 12.0 eV for hydrogen and 256 eV for propane. It is shown that this amount of heat must be concentrated in an area with a diameter of about 10 nm at the beginning of the nucleation process. The non-occurence of a relativistic increase in the bubble density—velocity curve supports the assumption that, at least in hydrogen, the bubbles are created by δ-electrons. In the case of helium a detailed calculation is given of the way in which a δ-electron transfers its energy to the liquid. It can be shown that direct heating of the liquid by electrons is only a minor effect, but that excitation and ionization can produce the necessary heat for bubble formation by their subsequent processes, deexcitation and recombination. In the presented model the liquid is treated as gas-like, only those effects which are observed in gaseous helium are incorporated in the mechanism. It is made clear that a single deexcitation or recombination event is not sufficient to create a bubble, but that a number of them have to cooperate. A discussion about bubble creation in hydrogen and in more complex liquids is presented. The influence of molecular effects, the possibility of collective excitations and the consequences of complex chemical behaviour are estimated. It is seen to be plausible that the nucleation process takes place more easily in more complex liquids, because of the greater variety of ways in which the charged particles can transfer their energy to the liquid. Mention is made of the possibility that, in complex liquids, bubbles can be created by an excitation of lower atomoc levels rather than by the production of δ-electrons. This may explain the occurence of a relativistic rise in the bubble density—velocity curve in liquids like freon.

The theory of condensation of supersaturated vapours in the absence of ions

A brief review of the condensation theory of Becker & Döring (1935) and Frenkel (1946) is given. It is shown that the theory is subject to the limitation that it assumes that small molecular complexes behave like liquid droplets. This is not the case for complexes consisting of a few molecules only, so that the rate of condensation expected from the theory may be altered by an appreciable amount. The Becker & Döring expression for critical supersaturation is compared with the cloud-chamber measurements of Volmer & Flood (1934), taking into account the rapid heating of the gas after the fast expansion. It is found to be in approximate agreement for water and some of the alcohols, but methyl alcohol, benzene and carbon tetrachloride show large discrepancies. More measurements of critical supersaturations are needed.

An Upper Limit to the Metastability of Supersaturated Vapors

A thermodynamic criterion for (mechanical) instability is applied to the condensation of supersaturated vapors. Values of the maximum thermodynamic compressibility of a vapor as a function of temperature are calculated from the Van der Waals' and Berthelot Equations of State and from a newly developed, modified equation. In all cases, the upper limits predicted lie above the reported experimental values. With the exception of the Van der Waals' equation the predicted values appear much too high. The bearing of these results on the utility of the same thermodynamic criterion for estimating maximum tensile strength of liquids is discussed.