The Airborne Microparticle: Its Physics, Chemistry, Optics, and Transport Phenomena

ISBN-13: 9783642628061 / Angielski / Miękka / 2012 / 834 str.

E. James Davis; Gustav Schweiger

Opis

It has been thirty years since one of the authors (EJD) began a collaboration with Professor Milton Kerker at Clarkson University in Potsdam, New York using light scattering methods to study aerosol processes. The development of a relatively short-lived commercial particle levitator based on a modification of the Millikan oil drop experiment attracted their attention and led the author to the study of single droplets and solid microparticles by levitation methods. The early work on measurements of droplet evaporation rates using light scattering techniques to determine the size slowly expanded and diversified as better instrumentation was developed, and faster computers made it possible to perform Mie theory light scattering calculations with ease. Several milestones can be identified in the progress of single microparticle studies. The first is the introduction of the electrodynamic balance, which provided more robust trapping of a particle. The electrodynamic levitator, which has played an important role in atomic and molecular ion spectroscopy, leading to the Nobel Prize in Physics in 1989 shared by Wolfgang Paul of Bonn University and Hans Dehmelt of the University of Washington, was easily adapted to trap microparticles. Simultaneously, improvements in detectors for acquiring and storing light scattering data and theoretical and experimental studies of the interesting optical properties of microspheres, especially the work on morphology- dependent resonances by Arthur Ashkin at the Bell Laboratories, Richard Chang, from Yale University, and Tony Campillo from the Naval Research Laboratories in Washington D. C.

Spis treści

1 Background.- 1.1 Introduction.- 1.2 Light Scattering.- 1.2.1 Tyndall’s Observations.- 1.2.2 Rayleigh Scattering.- 1.2.3 Lorenz-Mie-Debye Theory.- 1.2.4 Inelastic Scattering.- 1.2.5 Quasi-Elastic Scattering.- 1.3 Microparticle Transport Phenomena.- 1.3.1 Kinetic Theory.- 1.3.2 Continuum Theory.- 1.4 Transport in the Transition Regime.- 1.4.1 Transition Regime Mass Transfer.- 1.4.2 Transition Regime Heat Transfer.- 1.4.3 The Cunningham Correction.- 1.5 Particle Charge.- 1.5.1 The Cavendish Laboratory Experiments.- 1.5.2 Millikan’s Experiments.- 1.6 Applications and Adaptations of MODE.- 1.6.1 Brownian Motion in Gases.- 1.6.2 Microdroplet Evaporation.- 1.6.3 Knudsen Aerosol Evaporation.- 1.6.4 A Kinetic Theory Approximation.- 1.6.5 Light Scattering Measurements.- 1.7 Particle Levitation Instrumentation.- 1.7.1 Magnetic Suspension.- 1.7.2 Electrostatic Suspension.- 1.7.3 Electrodynamic Suspension.- 1.7.4 Optical Levitation.- 1.7.5 Acoustic Levitation.- 1.8 The Vibrating Orifice Generator.- 1.9 Applications of Single Particle Devices.- 1.9.1 Concentrated Electrolyte Solutions.- 1.9.2 Microparticle Spectroscopies.- 1.9.3 Gas/Particle Chemical Reactions.- 1.9.4 Evaporation/Condensation Processes.- 1.9.5 Physical and Interfacial Properties of Microparticles.- 1.10 References.- 2 Particle Levitation.- 2.1 Introduction to Levitation Phenomena.- 2.2 Electrostatic Balances.- 2.3 Electrodynamic Balances.- 2.4 Principles of Electrodynamic Trapping.- 2.4.1 The Equation of Particle Motion.- 2.4.2 Trapping in a Potential Well.- 2.5 EDB Electric Fields.- 2.5.1 Spherical Harmonics Solution.- 2.5.2 Ring Charge Simulation.- 2.5.3 Electrode Asymmetries.- 2.5.4 Optimum Balance Shapes.- 2.6 Particle Stability in an EDB.- 2.6.1 The Ion Trap.- 2.6.2 The Microparticle Trap.- 2.6.3 Müller’s Solution.- 2.6.4 Continued Fractions.- 2.6.5 Numerical Solutions.- 2.7 Nonhyperboloidal Balances.- 2.7.1 The Single Ring.- 2.7.2 Straubel’s Three Disk Balance.- 2.8 Optical Levitation.- 2.8.1 The Optical Levitator.- 2.8.2 The Single-Beam Gradient Force Trap.- 2.9 Acoustic Levitation.- 2.9.1 Acoustic Pressure.- 2.9.2 The Barotropic Fluid.- 2.9.3 Energy Density of an Acoustic Wave.- 2.9.4 Acoustic Pressure on a Sphere.- 2.9.5 Particle Velocity and Phase Shift.- 2.9.6 Acoustic Levitators.- 2.9.7 Acoustic Measurements.- 2.10 References.- 3 Elastic Light Scattering.- 3.1 Introduction.- 3.2 Maxwell Equations.- 3.2.1 Constitutive Relations.- 3.2.2 Time-Harmonic Fields.- 3.2.3 Power and Energy Density.- 3.2.4 Polarization.- 3.3 Dipole Radiation.- 3.4 Cross Sections and Radiation Pressure.- 3.4.1 Cross Sections and Efficiencies.- 3.4.2 Radiation Pressure.- 3.4.3 Radiation Pressure Measurement.- 3.5 Rayleigh Scattering.- 3.5.1 Irradiance of Scattered Light.- 3.5.2 Polarization of the Scattered Light.- 3.6 Electromagnetic Theory.- 3.6.1 Multipole Expansion.- 3.6.2 Lorenz-MieTheory.- 3.6.3 Cross Sections and Efficiencies.- 3.6.4 Angular Scattering.- 3.6.5 Morphology-Dependent Resonances.- 3.6.6 Polarization Ratio.- 3.6.7 Electromagnetic Energy Absorption.- 3.6.8 Coated Spheres.- 3.7 Coupled Dipole Theory.- 3.8 Generalized Lorenz-Mie Theory.- 3.9 The T-matrix Method.- 3.10 Geometrical Optics.- 3.10.1 Basic Laws of Geometrical Optics.- 3.10.2 Interfaces.- 3.10.3 Transmitted and Scattered Fields.- 3.10.4 Optics of the Rainbow.- 3.11 Resonances.- 3.11.1 The Localization Principle.- 3.11.2 Resonance Conditions.- 3.11.3 Resonance Condition for Spherical Geometry.- 3.11.4 Quality factor Q and Line Width.- 3.12 References.- 4 Basic Single Particle Measurements.- 4.1 Force Measurement.- 4.2 Aerodynamic Drag.- 4.3 Levitation Characteristics.- 4.3.1 Direct Measurement of Co.- 4.3.2 Stability Measurements.- 4.3.3 SHEL Data.- 4.3.4 Double-Ring Measurements.- 4.3.5 Multiple Particle Trapping.- 4.4 Radiometric and Phoretic Forces.- 4.4.1 Radiation Pressure Force.- 4.4.2 Optical Trap Measurement.- 4.4.3 Phoretic Forces.- 4.4.4 Photophoresis Measurements.- 4.4.5 Thermophoresis Measurements.- 4.5 Mass Measurement.- 4.6 Aerodynamic Size Measurement.- 4.6.1 The Laminar Jet EDB.- 4.6.2 Sedimentation.- 4.6.3 Particle Stability Measurements.- 4.6.4 Phase Lag Measurements.- 4.7 Optical Size.- 4.7.1 Phase Functions.- 4.7.3 Polarization Ratio Measurement.- 4.7.4 Resonance Spectra.- 4.7.5 Diffraction.- 4.7.6 Phase Doppler Anemometry.- 4.8 Charge Measurement.- 4.8.1 Evaporating Droplets.- 4.8.2 The Rayleigh Limit of Charge.- 4.8.3 Droplet Chain Charge Measurement.- 4.9 Photoelectric Work Function.- 4.10 References.- 5 Continuum Transport Processes.- 5.1 Transport Regimes.- 5.2 Thermal Energy Equation.- 5.3 Convective Diffusion Equation.- 5.4 Equations of Motion.- 5.4.1 Stokes Flow.- 5.4.2 Higher Order Solutions.- 5.4.3 Fluid Spheres.- 5.4.4 Ellipsoidal Particles.- 5.4.5 Other Non-spherical Particles.- 5.5 Heat Transfer.- 5.5.1 Stagnant Fluid.- 5.5.2 Electromagnetic Heating.- 5.5.3 Internal Temperatures with Pulsed Heating.- 5.5.4 External Temperatures in Pulsed Heating.- 5.5.5 Particle Cooling by Thermal Emission.- 5.6 Mass Transfer.- 5.6.1 Heat and Mass Flux Relations.- 5.6.2 Single Component Droplet Evaporation.- 5.6.3 Quasi-Steady State.- 5.6.4 Multicomponent Evaporation Measurements.- 5.6.5 Condensational Particle Growth.- 5.7 Convective Transport Processes.- 5.7.1 Heat and Mass Transfer with Stokes Flow.- 5.7.2 Heat and Mass Transfer for Large Peclet Numbers.- 5.7.3 Heat and Mass Transfer for Re > 0.1.- 5.8 References.- 6 Non-Continuum Processes.- 6.1 Introduction.- 6.1.1 Applications.- 6.1.2 Historical Perspective.- 6.2 Statistical Mechanics.- 6.2.1 Intermolecular Forces.- 6.2.2 The Equilibrium Gas.- 6.2.3 The Gas Pressure.- 6.2.4 Properties of a Uniform Gas.- 6.3 Collision Processes.- 6.3.1 Scattering Cross Sections.- 6.3.2 Mean Free Path.- 6.4 The Boltzmann Equation.- 6.4.1 Collision Integral for Hard Spheres.- 6.4.2 Collision Integral for Maxwellian Molecules.- 6.4.3 BGK Approximation.- 6.4.4 Linearized Boltzmann Equation.- 6.5 The Non-Uniform Gas.- 6.6 The Free-Molecule Regime.- 6.6.1 The Mass Flux.- 6.6.2 The Momentum and Kinetic Energy Fluxes.- 6.6.3 The Drag Force.- 6.7 The Transition Regime.- 6.7.1 Single Component Evaporation and Condensation.- 6.7.2 Drag Force on Spheres.- 6.7.3 Evaporation and Condensation.- 6.7.4 Interpolation Formulas for Heat Transfer.- 6.8 References.- 7 Thermodynamic and Transport Properties.- 7.1 Droplet Thermodynamics.- 7.2 Single Component Systems.- 7.2.1 Estimation of Lennard-Jones Parameters.- 7.2.2 Determination of pi0, ?ii ?ii.- 7.2.3 Alternate Vapor Pressure Determination.- 7.3 Multicomponent Systems.- 7.3.1 Aqueous Salt Solution Droplets.- 7.3.2 Theory of Electrolyte Solutions.- 7.3.3 Activity Measurement.- 7.3.4 Deliquescence.- 7.3.5 Crystallization.- 7.4 Non-aqueous Systems Activity Coefficient Measurement.- 7.5 Partially Miscible Systems.- 7.5.1 Surfactant Solutions.- 7.5.2 Agricultural Sprays.- 7.5.3 Coated Droplets.- 7.6 References.- 8 Inelastic Light Scattering.- 8.1 Introduction.- 8.2 Raman Scattering: Classical Description.- 8.1.1 Stokes and anti-Stokes Raman Scattering.- 8.1.2 Intensity of Raman Scattering.- 8.1.3 Selection Rules.- 8.1.4 State of Polarization of Scattered Light.- 8.3 Quantum Mechanical Description.- 8.3.1 Review of Some Basic Relations.- 8.3.2 Quantum States of Atoms and Molecules.- 8.3.3 Light Scattering.- 8.3.4 Placzek’s Polarizability Theory.- 8.3.5 Properties of Raman Scattering.- 8.3.6 Resonance Raman Scattering.- 8.4 Absorption and Emission of Radiation.- 8.4.1 The Electron Oscillator Model.- 8.4.2 Line Shape.- 8.4.3 Depolarization.- 8.4.4 Einstein Coefficients.- 8.4.5 Black Body Radiation.- 8.4.6 Amplification of Light.- 8.4.7 Resonant Cavities.- 8.5 Nonlinear Processes.- 8.5.1 The Nonlinear Wave Equation.- 8.5.2 Stimulated Raman Scattering.- 8.6 Particle Specific Effects.- 8.6.1 Multipole expansion.- 8.6.2 Ray Tracing.- 8.6.3 Scattering Cross Section.- 8.6.4 Morphology Dependent Resonance Effects.- 8.6.5 Stimulated Processes.- 8.7 References.- 9 Spectroscopies and Mass Spectrometry.- 9.1 Spectroscopic and Spectrometric Techniques.- 9.2 Photothermal Spectroscopies.- 9.3 Phase Fluctuation Optical Heterodyning.- 9.4 Photothermal Modulation.- 9.4.1 Principles of SRMS.- 9.4.2 Photothermal Modulation of Scattered Light.- 9.4.3 Photothermal Modulation of MDRs.- 9.4.4 FTIR Microdroplet Spectroscopy.- 9.5 Photophoretic Spectroscopy.- 9.6 Linear Raman Spectroscopy.- 9.6.1 Instrumentation.- 9.6.2 Evaporating Liquid Particles.- 9.6.3 Radial Profiling.- 9.6.4 Liquid Solid and Solid Liquid Phase Changes.- 9.6.5 Temperature Measurements.- 9.7 Nonlinear Spectroscopic Methods.- 9.7.1 Stimulated Raman Scattering.- 9.7.2 Resonance Raman Scattering.- 9.7.3 Lasing.- 9.8 Laser Induced Fluorescence.- 9.8.1 Single Particles and Sprays.- 9.8.2 Particle Temperature.- 9.8.3 Biological Aerosol Particles.- 9.9 Laser Induced Incandescence.- 9.9.1 Energy and Mass Balance.- 9.9.2 Particle Sizing.- 9.9.3 Soot-volume Fraction.- 9.10 Mass Spectrometry.- 9.10.1 Instrumentation.- 9.10.2 Particle Sizing.- 9.10.3 Mass Spectrometry Results.- 9.11 References.- 10 Particle Chemical Reactions.- 10.1 Introduction.- 10.2 Atmospheric Particles.- 10.3 Ozone Depletion.- 10.4 Desulfurization.- 10.5 Microparticle Reactors.- 10.5.1 Flow Reactors.- 10.5.2 VOAG Reactors.- 10.5.3 EDB Reactors.- 10.5.4 EDB Raman Systems.- 10.5.5 Optical Levitation Raman Systems.- 10.6 Microparticle Reaction Measurements.- 10.6.1 Single Particle Desulfurization Reactions.- 10.6.2 Other Microparticle Reactions.- 10.7 Microparticle Production.- 10.7.1 Metal Oxide Aerosol Processes.- 10.7.2 Polymeric Microspheres via Aerosol Processes.- 10.8 Gas/Droplet Reaction Rate Theory.- 10.8.1 Gas Uptake with a Pseudo-First Order Reaction.- 10.8.2 Gas Uptake with No Reaction.- 10.8.3 Time-Varying Gas Concentration.- 10.8.5 The Small Penetration Approximation.- 10.8.6 The Resistance Model of Gas Uptake.- 10.8.7 Formation of Coated Particles.- 10.9 References.- 11 Phoretic and Radiometric Phenomena.- 11.1 Introduction to Phoretic Forces.- 11.2 Radiation Force.- 11.3 Continuum and Near-Continuum Transport.- 11.3.1 Governing Equations.- 11.3.2 Velocity Slip.- 11.3.3 Temperature Jump.- 11.3.4 Thermal Creep.- 11.3.5 Diffusion Slip.- 11.4 Phoretic Forces in the Near-Continuum Regime.- 11.4.1 Solid Sphere in a Pure Isothermal Gas with Slip Flow.- 11.4.2 Solid in a Pure Gas with External Temperature Gradient.- 11.4.3 Solid in a Diffusing Isothermal Binary Gas.- 11.4.4 Counterdiffusion with No Bulk Flow.- 11.4.5 Diffusion Through a Stationary Gas.- 11.4.6 Combined Diffusiophoresis and Thermophoresis.- 11.5 Photophoresis in the Near-Continuum Regime.- 11.5.1 Photophoresis of a Strongly Absorbing Sphere.- 11.5.2 Photophoresis of a Volatile Droplet.- 11.5.3 Photophoresis with Diffusion-Controlled Evaporation.- 11.5.4 Photophoresis with Convective Evaporation.- 11.6 Thermophoresis.- 11.7 Phoretic Forces in the Knudsen Regime.- 11.7.1 Thermophoresis in the Transition Regime.- 11.7.2 Thermophoresis Measurements.- 11.7.3 State of the Art of Thermophoresis.- 11.8 References.

Blurb

This book is an extensive yet self-contained reference of single microparticle studies as they have been performed for many years by the authors. With the range of theoretical and experimental tools available it has become possible to use the many unique properties of droplets and small particles to investigate phenomena as diverse as, linear and nonlinear optics, solution thermodynamics, gas/solid and gas/liquid chemical reactions, transport properties such as gas phase diffusion coefficients, rate processes in the continuum and non-continuum regimes, trace gas uptake by aerosol droplets related to atmospheric chemistry and ozone depletion, phoretic phenomena, Raman spectroscopy, particle charge, evaporation and condensation processes. Throughout the book the main concern of the authors was to provide the reader with a visualization of the significance and application of the theory by experimental results.