Extinction, efficiency

X = log(D/Dp), Eg is the mass extinction efficiency for species i, and m3(x) is the volume average refractive index as a function of X. Strict application of Equation (1) requires information on all species. 

The species mass extinction efficiency. Eg, can be theoretically determined from Mie s classical solution to light extinction by a sphere in an infinite medium. Computer routines are available to calculate single particle extinction efficiencies, and, hence. Eg ( ). If the mass distribution of each species is... 

Sulfate Average Mass Extinction Efficiency, ct. Comparison of Statistically Inferred Values... 

Aerosol Species Average Mass Extinction Efficiency mVg % Decrease in Current Visual Range Due to Additional 2 pg/m of Species... 

Figure 4.6 Extinction efficiencies for water droplets in air plotting increment = 0.01 /xm...

The extinction efficiency of a nonabsorbing sphere is equal to its scattering efficiency for such a sphere, provided that it is sufficiently large, it necessarily follows that (2ref] + Qit = 1 and... 

In a similar manner we obtain the scattering and extinction efficiencies when the incident electric field is polarized perpendicular to the xz plane (Case II) ... 

Consider now a spherical void (e = 1) in an otherwise homogeneous medium. Light is not absorbed by such a void, but it can influence the absorption of light in the surrounding medium. The condition for a resonance in the extinction efficiency of a small spherical void follows readily from (12.17) ... 

Figure 12.1 Calculated extinction efficiencies of silicon carbide spheres in air. The wave number denotes the inverse of the wavelength.

Figure 12.2 Calculated extinction efficiencies of a silicon carbide sphere (0.1 /im) in air and in potassium bromide.

The programs should not be used without an attitude of healthy skepticism. We tested them as much as possible, but they undoubtedly contain hidden flaws. In the following appendixes we discuss criteria that the programs were required to satisfy. Some of them are obvious the extinction efficiency must not be less than the scattering efficiency, and both must be nonnegative others are more subtle. 

Considering an incident plane wave on a sphere of no net surface charge, the scattering and extinction efficiency factor for the field far away from the particle can be approximated by [Van de Hulst, 1957]... 

Where, t(X) is the turbidity at the wavelength X, N the number of particles/ml, C the concentration in g/ml, D the particle diameter, f(D) the frequency distribution of particle sizes, p the density of the particles, m is the complex refractive index ratio and Q(a,m) is the Mie overall extinction efficiency. The extinction efficiency is given by... 

For monodisperse systems in the large particle size regime, where the extinction efficiency can be assumed constant and approximately equal to 2, equation 2 becomes... 

The problem of deciding on a particular average diameter (or diameters) to be used in the calculation of the extinction efficiency can be formulated as finding average particle diameters, Dav, such that... 

Then on the basis of the first constraint, the extinction efficiency is expanded in power series of aav to yield... 

The coefficients of the power series expansion of the extinction efficiency, to a 5th order approximation, were derived by Penndorf ( 17) and independently at our laboratories using Macsyma (18). The coefficients of the series are ... 

The instantaneous output of the detector (S) can be related to the concentration of material of a given size by dividing by the extinction efficiency (Q of the particles present in the... 

---