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

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.

Table of Contents:
1 Background.- 1.1 Introduction.- 1.2 Light Scattering.- 1.3 Microparticle Transport Phenomena.- 1.4 Transport in the Transition Regime.- 1.5 Particle Charge.- 1.6 Applications and Adaptations of MODE.- 1.7 Particle Levitation Instrumentation.- 1.8 The Vibrating Orifice Generator.- 1.9 Applications of Single Particle Devices.- 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.- 2.5 EDB Electric Fields.- 2.6 Particle Stability in an EDB.- 2.7 Nonhyperboloidal Balances.- 2.8 Optical Levitation.- 2.9 Acoustic Levitation.- 2.10 References.- 3 Elastic Light Scattering.- 3.1 Introduction.- 3.2 Maxwell Equations.- 3.3 Dipole Radiation.- 3.4 Cross Sections and Radiation Pressure.- 3.5 Rayleigh Scattering.- 3.6 Electromagnetic Theory.- 3.7 Coupled Dipole Theory.- 3.8 Generalized Lorenz-Mie Theory.- 3.9 The T-matrix Method.- 3.10 Geometrical Optics.- 3.11 Resonances.- 3.12 References.- 4 Basic Single Particle Measurements.- 4.1 Force Measurement.- 4.2 Aerodynamic Drag.- 4.3 Levitation Characteristics.- 4.4 Radiometric and Phoretic Forces.- 4.5 Mass Measurement.- 4.6 Aerodynamic Size Measurement.- 4.7 Optical Size.- 4.8 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.- 5.5 Heat Transfer.- 5.6 Mass Transfer.- 5.7 Convective Transport Processes.- 5.8 References.- 6 Non-Continuum Processes.- 6.1 Introduction.- 6.2 Statistical Mechanics.- 6.3 Collision Processes.- 6.4 The Boltzmann Equation.- 6.5 The Non-Uniform Gas.- 6.6 The Free-Molecule Regime.- 6.7 The Transition Regime.- 6.8 References.- 7 Thermodynamic and Transport Properties.- 7.1 Droplet Thermodynamics.- 7.2 Single Component Systems.- 7.3 Multicomponent Systems.- 7.4 Non-aqueous Systems Activity Coefficient Measurement.- 7.5 Partially Miscible Systems.- 7.6 References.- 8 Inelastic Light Scattering.- 8.1 Introduction.- 8.2 Raman Scattering: Classical Description.- 8.3 Quantum Mechanical Description.- 8.4 Absorption and Emission of Radiation.- 8.5 Nonlinear Processes.- 8.6 Particle Specific Effects.- 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.- 9.5 Photophoretic Spectroscopy.- 9.6 Linear Raman Spectroscopy.- 9.7 Nonlinear Spectroscopic Methods.- 9.8 Laser Induced Fluorescence.- 9.9 Laser Induced Incandescence.- 9.10 Mass Spectrometry.- 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.- 10.6 Microparticle Reaction Measurements.- 10.7 Microparticle Production.- 10.8 Gas/Droplet Reaction Rate Theory.- 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.- 11.4 Phoretic Forces in the Near-Continuum Regime.- 11.5 Photophoresis in the Near-Continuum Regime.- 11.6 Thermophoresis.- 11.7 Phoretic Forces in the Knudsen Regime.- 11.8 References.