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Production of ultrafine monodisperse aerosols by condensation
Aerosol Science. 1975, Vol. 6. pp. 159 160. Pergamon Press. Printed in Great Britain.
CURRENT WORK ON NUCLEATION C o m p i l e d b y D. STAUVVER Institute of Theoretical Physics, University, 66 Saarbriicken 1l, West Germany Brief abstracts of work which has not yet been published may be submitted to the compilers for inclusion in this section.
Condensation of a supersaturated vapor--II. The homogeneous nucleation of the n-alkyl benzenes. By J. L. KATZ, C. J. SCOPPA II, N. GANESH KUMARand P. MIRABEL, Department of Chemical Engineering, Clarkson College of Technology, Potsdam, New York 13676, U.S.A. The design of an improved version of the upward thermal diffusion cloud chamber is described. Such a chamber was constructed and used to measure the supersaturation required to observe a rate of homogeneous nucleation of ~ 3 drops cm 3 see-1. Measurements were made on benzene, toluene, orthoxylene and n-butylbenzene over as much as a 150° range of temperature. The results obtained are compared to the predictions of the classical theory of homogeneous nucleation (Volmer-Becker-Di~ring-Zeldovich) and of the Lothe Pound theory. The classical theory is found to be in excellent agreement with the experimental results.
Homogeneous particle growth from the photoreaction of SOz with n-butane. By H. JORDANand R.-D. PENZHRON; Institut ftir angewandte Systemtechnik, Kernforschungszentrum, 75 Karlsruhe, West Germany. No abstract given; find approximately monodisperse particles.
The photoreaction of sulfur dioxide with hydrocarhons--II. Chemical and physical aspects of the formation of aerosols with butane. By R-D. PENZHORN, W. G. E1LBY, K. GI)NTHER and L. STIEGLITZ; Institut ffir Radiochemie, Kernforschungszentrum, 75 Karlsruhe, West Germany. A combined mass spectrometry/gas chromatography study of the aerosolic products from the photoreaction (above 290nm) of SO2 with some short-chain alkanes has been performed. Measurement of the product yields demonstrate that (i) the reaction of triplet SOz with alkanes involves as a primary step a proton abstraction and not an insertion and/or a dissociative collision, (ii) triplet SOz attacks C-H bonds specifically and shows in this respect resemblances to simple free radicals and atoms, and (iii) subsequent reactions are governed by the ease of formation and stability of the alkyl sulfonyl radicals (RSOz). Alkyl sulfonyl radicals tend to disproportionate rather than recombine, or proton abstract. The latter reaction, which would lead to a chain process, is not favoured, rather the alkyl sulfonyl radicals give rise to sulfonic acid and thiosulfonate via reactions involving the SO2H radical. Some derived rate constant ratios and phenomenological observations on the aerosol nature are presented.
Stratospheric sulfuric acid particle formation mechanisms. By C. S. KIANG and R. D. CADLE; National Center for Atmospheric Research, P.O. Box 3000, Boulder, Colorado 80303, U.S.A. The relative importance of the heterogeneous condensation process and the homogeneous heteromolecular nucleation process for the formation of sulfuric aci,d particles in the stratosphere is demonstrated. It is shown that the concentrations of sulfur dioxide and water, conversion rate of SO2 to H2SO 4 vapor, surface area of pre-existing particles and size of pre-existing particles are the parameters determining the formation mechanisms of stratospheric sulfuric acid particles. The results demonstrate that either process can dominate in the stratosphere depending on the local conditions. H2SO4-HNO3-H20 ternary aerosol formation mechanism in the stratosphere. By C. S. KIANG, R. D. CADLE (address as above) and G. K. YUE. An order of magnitude calculation of the characteristic time required for the homogeneous heteromolecular nucleation of new stratospheric particles involving the H2SO4-HNO3-H20 ternary system is presented. This characteristic time is compared with the characteristic time required for the homogeneous heteromolecular nucleation of sulfuric acid particles involving the H 2 S O ~ H 2 0 binary system and with the characteristic time for the H2SO 4 vapor condensing on the pre-existing particles. From the comparison of these characteristic times we show that this formation of new particles involving H2SO4-HNO3-H20 may be the most favorable mechanism for the formation of "sulfuric acid" particles in the stratosphere.
Production of ultrafine monodisperse aerosols by condensation. By G. TARRONI, V. PRODI, C. MELANDRI, G. F. BOMPANE,T. DE ZAIACOMOand M. FORMIGNANI; Laboratorio di Fisica Sanitaria del CNEN, 40138 Bologna, Italy. (To be published in J. Aerosol Science 6 (4).) In this paper the production of monodisperse aerosols in the ultrafine range is described, based on the general condensation scheme. The boiler is suppressed, as the material is fed directly to the reheater in the form of argon-borne particles. The reheater is alternatively an induction plasma torch or an induction graphite oven that allow a volume heating of the gas and a controlled vapor concentration and cooling rate. The range of particle size is 0.005-0-15 #m and overlaps with the size range produced by the conventional condensation (Sinclai~La Mer) generators. The geometric S.D. ranges from 1.3 to 1.1. 159
CURRENT WORK ON NUCLEATION C o m p i l e d b y D. STAUVVER Institute of Theoretical Physics, University, 66 Saarbriicken 1l, West Germany Brief abstracts of work which has not yet been published may be submitted to the compilers for inclusion in this section.
Condensation of a supersaturated vapor--II. The homogeneous nucleation of the n-alkyl benzenes. By J. L. KATZ, C. J. SCOPPA II, N. GANESH KUMARand P. MIRABEL, Department of Chemical Engineering, Clarkson College of Technology, Potsdam, New York 13676, U.S.A. The design of an improved version of the upward thermal diffusion cloud chamber is described. Such a chamber was constructed and used to measure the supersaturation required to observe a rate of homogeneous nucleation of ~ 3 drops cm 3 see-1. Measurements were made on benzene, toluene, orthoxylene and n-butylbenzene over as much as a 150° range of temperature. The results obtained are compared to the predictions of the classical theory of homogeneous nucleation (Volmer-Becker-Di~ring-Zeldovich) and of the Lothe Pound theory. The classical theory is found to be in excellent agreement with the experimental results.
Homogeneous particle growth from the photoreaction of SOz with n-butane. By H. JORDANand R.-D. PENZHRON; Institut ftir angewandte Systemtechnik, Kernforschungszentrum, 75 Karlsruhe, West Germany. No abstract given; find approximately monodisperse particles.
The photoreaction of sulfur dioxide with hydrocarhons--II. Chemical and physical aspects of the formation of aerosols with butane. By R-D. PENZHORN, W. G. E1LBY, K. GI)NTHER and L. STIEGLITZ; Institut ffir Radiochemie, Kernforschungszentrum, 75 Karlsruhe, West Germany. A combined mass spectrometry/gas chromatography study of the aerosolic products from the photoreaction (above 290nm) of SO2 with some short-chain alkanes has been performed. Measurement of the product yields demonstrate that (i) the reaction of triplet SOz with alkanes involves as a primary step a proton abstraction and not an insertion and/or a dissociative collision, (ii) triplet SOz attacks C-H bonds specifically and shows in this respect resemblances to simple free radicals and atoms, and (iii) subsequent reactions are governed by the ease of formation and stability of the alkyl sulfonyl radicals (RSOz). Alkyl sulfonyl radicals tend to disproportionate rather than recombine, or proton abstract. The latter reaction, which would lead to a chain process, is not favoured, rather the alkyl sulfonyl radicals give rise to sulfonic acid and thiosulfonate via reactions involving the SO2H radical. Some derived rate constant ratios and phenomenological observations on the aerosol nature are presented.
Stratospheric sulfuric acid particle formation mechanisms. By C. S. KIANG and R. D. CADLE; National Center for Atmospheric Research, P.O. Box 3000, Boulder, Colorado 80303, U.S.A. The relative importance of the heterogeneous condensation process and the homogeneous heteromolecular nucleation process for the formation of sulfuric aci,d particles in the stratosphere is demonstrated. It is shown that the concentrations of sulfur dioxide and water, conversion rate of SO2 to H2SO 4 vapor, surface area of pre-existing particles and size of pre-existing particles are the parameters determining the formation mechanisms of stratospheric sulfuric acid particles. The results demonstrate that either process can dominate in the stratosphere depending on the local conditions. H2SO4-HNO3-H20 ternary aerosol formation mechanism in the stratosphere. By C. S. KIANG, R. D. CADLE (address as above) and G. K. YUE. An order of magnitude calculation of the characteristic time required for the homogeneous heteromolecular nucleation of new stratospheric particles involving the H2SO4-HNO3-H20 ternary system is presented. This characteristic time is compared with the characteristic time required for the homogeneous heteromolecular nucleation of sulfuric acid particles involving the H 2 S O ~ H 2 0 binary system and with the characteristic time for the H2SO 4 vapor condensing on the pre-existing particles. From the comparison of these characteristic times we show that this formation of new particles involving H2SO4-HNO3-H20 may be the most favorable mechanism for the formation of "sulfuric acid" particles in the stratosphere.
Production of ultrafine monodisperse aerosols by condensation. By G. TARRONI, V. PRODI, C. MELANDRI, G. F. BOMPANE,T. DE ZAIACOMOand M. FORMIGNANI; Laboratorio di Fisica Sanitaria del CNEN, 40138 Bologna, Italy. (To be published in J. Aerosol Science 6 (4).) In this paper the production of monodisperse aerosols in the ultrafine range is described, based on the general condensation scheme. The boiler is suppressed, as the material is fed directly to the reheater in the form of argon-borne particles. The reheater is alternatively an induction plasma torch or an induction graphite oven that allow a volume heating of the gas and a controlled vapor concentration and cooling rate. The range of particle size is 0.005-0-15 #m and overlaps with the size range produced by the conventional condensation (Sinclai~La Mer) generators. The geometric S.D. ranges from 1.3 to 1.1. 159