snompy.pdm.refl_coef_qs_from_eff_pol

pdm.refl_coef_qs_from_eff_pol(alpha_eff, z_tip=None, r_tip=None, eps_tip=None, alpha_tip=None)

Return the quasistatic reflection coefficient corresponding to a particular effective polarizability using the point dipole model.

Parameters:

alpha_effcomplex

Effective polarizability of the tip and sample.

z_tipfloat

Height of the tip above the sample.

r_tipfloat

Radius of curvature of the AFM tip.

eps_tipcomplex

Dielectric function of the sample. Used to calculate alpha_tip, and ignored if alpha_tip is specified. If both eps_tip and alpha_tip are None, the sphere is assumed to be perfectly conducting.

alpha_tipcomplex

Polarizability of the conducting sphere used as a model for the AFM tip.

Returns:

betacomplex, masked array

Quasistatic reflection coefficient of the interface.

See also

eff_pol

The inverse of this function.

refl_coef_qs_from_eff_pol_n

The demodulated equivalent of this function.

Notes

This function implements the equation

\[\beta = \frac{(\alpha_{eff} - \alpha_{tip})}{f \alpha_{eff}}\]

where \(\alpha_{eff}\) is alpha_eff, and \(f\) is a function encapsulating the PDM geometry, taken from reference [1]. Here it is given by geom_func().

References

[1]

A. Cvitkovic, N. Ocelic, and R. Hillenbrand, “Analytical model for quantitative prediction of material contrasts in scattering-type near-field optical microscopy,” Opt. Express, vol. 15, no. 14, p. 8550, 2007, doi: 10.1364/oe.15.008550.