Table of Parameters

User Guide

Table of input/output parameters

The following table contains a complete list of input/output parameters. The third column of the table specifies whether a parameter is an input or an output parameter:

I means that the parameter can be used only as an input parameter
O means that the parameter can be used only as an output parameter
I/O means that the parameter can be both an input and output parameter.

The list of input parameters is redundant: you can enter the particle's dimension by entering the radius r , the diameter d or the volume vol. Instead of the wavelength lambda you can use the frequency f, the inverse wavelength invlambda, or the wavenumber k. For the material properties of the particle and the surrounding medium you can specify the relative permittivity (dielectric constant) or the refractive index. This redundance of parameters guarantees a maximum of flexibility of the program.

Symbolic name	Description	Input/output (I/O)
f	Frequency of light in Gigahertz	I/O
invlambda	inverse wavelength in vacuum	I/O
lambda	wavelength in vacuum	I/O
k	wave number in vacuum = 2*pi / lambda	I/O
d	diameter of particle	I/O
r	radius of particle	I/O
vol	volume of particle	I/O
x	size parameter	I/O
epsmed	relative dielectric function (permittivity) of surrounding medium	I
refmed	relative refractive index of surrounding medium	I/O
eps	real part of the relative dielectric function (permittivity) of the particle	I
epsim	imaginary part of the relative dielectric function (permittivity) of the particle	I
ref	real part of refractive index of the particle	I/O
refim	imaginary part of refractive index of the particle	I/O
theta	scattering angle in degrees (theta=0: forward scattering, theta=180: backscattering)	I/O
Qext	extinction efficiency	O
Qsca	scattering efficiency	O
Qabs	absorption efficiency	O
Qb	backscattering efficiency	O
A	albedo	O
g	asymmetry, scattering cosine	O
Cext	extinction cross-section	O
Csca	scattering cross-section	O
Cabs	absorption cross-section	O
Cb	backscattering cross-section	O
etaExt	extinction cross-section per particle volume	O
etaSca	scattering cross-section per particle volume	O
etaAbs	absorption cross-section per particle volume	O
s11	normalized scattered irradiance at angle theta; unpolarized incident light	O
ss	normalized scattered irradiance at angle theta; perpendicular polarization	O
sp	normalized scattered irradiance at angle theta; parallel polarization	O
p	degree of linear polarization (for incident unpolarized light)	O

Please note:

the scattered irradiances s11, ss, and sp are normalized according to the conventions in Bohren and Huffman's book. Multiply s11, ss, sp with I0* (lambda/(2*pi*R))^2 to obtain the intensity at the detector (R: distance particle-detector; I0: Intensity of incident light at the particle's location).
evaluation of input data is case insensitive, i.e, qext, Qext, and qEXT, refer to the same parameter
Length units are irrelevant in most cases, as long as you use them consistently for all quantities. For instance, if you enter the particle's radius and the wavelength in nm, then the cross-sections will be in units of nm^2. Exception: if you use the frequency as input, then the frequency unit is Gigahertz and the length unit is cm.