Particle optics

Theory. In the general case where rigid revolution ellipsoidal particles in solution possess both a permanent and an induced dipolar moment colinear with the particle optical axis, the theory derived by Tinoco predicts the following behaviour of the solution birefringence An(t) in the limit of weak electric field (6). 

Liu, L., and M. H. Smith, Urban and Rural Aerosol Particle Optical Properties, Atmos. Environ., 29, 3293-3301 (1995). 

In optical methods, extremely dilute aqueous or air-fluidized pigment suspensions are almost exclusively used. Instruments for the 0.1-10 pm particle size region mostly use Frauenhofer diffraction with additional correction for Mie scattering on small particles. Optical methods allow quick and reproducible measurements. Unfortunately, information is not usually available concerning the optical constants of the sample this causes drawbacks as regards absolute particle size data. 

Recent developments in surface-characterization methods have been made possible to a great extent by technological advances in areas such as lasers, ultra-high vacuum, charged-particle optics, and computer science. The surface-analysis techniques are commonly used to probe the interface between two phases after one phase is removed, but there is now a growing demand for additional methods for in situ interface characterization. 

Initially, particle optical density values increased slowly, but in the vicinity where the additives get depleted (-10,000 km), particle density values increased... 

Single-particle optical analyzers are especially useful for continuous measurement of particles of uniform physical properties. However, as discussed earlier, uncertainties develop in the measurement of particle clouds that are heterogeneous in composition because the refractive index may vary from particle to particle. Thus, in making atmospheric aerosol measurements, workers have assumed an average refractive index characteristic of the mixture to estimate a calibration curve or have reported data in terms of the equivalent particle diameter for a standard aerosol, such as suspended polystyrene latex spheres. 

Single-particle optical counters cannot be easily used for measuring high aerosol concentrations. Whitby and Liu (1967) have shown that if many small particles are in the illuminated sensitive volume of this type of instrument at the same time, significant errors are introduced because the particles are considered by the detector to be fewer in number and greater in size. Thus there is a practical upper limit on the aerosol concentration that can be measured by such an instrument, being on the order of 1000 to 10,000 particles per cubic centimeter. 

PSS Accusizer 780/SPOS Single particle optical sizer consists of a patented autodilution stage, single particle optical sensor, pulse height analyzer/counter (PHA), systems computer/processor and software control. The autodiluter performs a continuous dilution of the concentrated sample... 

The most frequently-used lenses in electron optics are aperture lenses or tube (cylindrical) lenses. There is a substantial literature on the design and characteristics of electron lenses and on charged-particle optics. Harting and Read (1976), Hawkes and Kasper (1988) and Wollnik (1987) are especially useful. 

Aerosol particle optical thickness AOT, Dimensionless Tep = J Oep Total optical thickness (or commonly optical depth) T= — In r cos 0g, where T is transmittance of direct solar beam for solar zenith angle 0q optical thickness (or commonly optical depth) due to extinction by aerosol particles r p = t — Tg, where Tg is optical thickness arising from scattering and absorption by gases depends on wavelength... 

Aerosol particle optical thickness (AOT) Sun photometry Beer s law using sun as light source -h... 

Another type of single-particle optical method is interference microscopy or microrheology (Mason et al. 1997 Gittes et al. 1997). In this method, the thermally driven motion... 

Nicoli, D.F. Wu, J.S. Chang, Y.J. McKenzie, D.C. Hasapidis, K. Automatic high resolution particle size analysis by single particle optical sensing. Am. Lab. 1992, July 24 (8), 39. 

In addition,there are several experimental options available for particle size measurement alone. They include single particle optical sensing (SPOS), laser diffraction (LD), and ultrasound attenuation (UA). 

Foss, C.A. Jr, Hornyak, G.L., Stochkert, J.A. and Martin, C.R. (1994) Template-synthesis nanoscopic gold particles optical spectra and the effects of particle size and shape. J. Phys. Chem., 98, 2963-2971. 

Small-size semiconductor particles optical properties... 

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