ABSTRACT
The photophoretic force is described by a comprehensive model containing aspects of both the optical local-field and gas-dynamic properties. It is shown that the model is in good agreement with detailed experimental data and provides a new means for measuring optical constants of microparticles.
ABSTRACT
The absorption spectrum of a single micrometer-sized aerosol particle is measured for the first reported time in the IR. Particle absorption is determined through the IR modulation of visible scattered light near a structure resonance. This technique, termed structure resonance modulation spectroscopy, is used to measure the IR absorption spectrum of an (NH(4))(2)SO(4) aerosol droplet of 5.4-microm diameter in the region from 970 to 1280 cm(-1). The resulting spectrum, when fitted by Mie theory, enables one to determine the molecular composition of the droplet.
ABSTRACT
Calculations are presented for the photophoretic force on a spherical aerosol particle with size much larger than the mean free path of the surrounding gas molecules. Very good agreement is shown with recent experimental data. The results show that both components of the complex refractive index can be inferred from radiometric measurements.
ABSTRACT
The internal and external field solutions for a composite particle are used to show the importance of the few angstroms closest to the surface in determining the radiative properties of micron-sized particulates. The physical mechanism responsible for the enhanced emissivity and the connection with surface waves are presented.
ABSTRACT
The differential scattering cross section for single carbon particles is measured in the visible. The data are mathematically inverted to obtain the complex index of refraction and particle radius.
