# Multilayer Reflectivity

• Top Material: . Density: gm/cm^3.
(enter negative value to use tabulated density.)
• Bottom Material: . Density: gm/cm^3.
• Multilayer Period: nm.
• Ratio of (Bottom layer thickness)/(Period): .
• Interdiffusion thickness : nm (Sigma).
• Number of periods: (enter negative value for semi-infinite multilayer.)
• Substrate Material: . Density: gm/cm^3.
• Polarization: (-1 < pol < 1) where s=1, p=-1 and unpolarized=0.
• Scan from to in steps (< 500).
(NOTE: Energies must be in the range 30 eV < E < 30,000 eV, Wavelength between 0.041 nm < Wavelength < 41 nm, and Angles between 0 & 90 degrees.)
• At fixed =
To request a press this button:

To reset to default values, press this button: .

## Explanation of Tables

Reflectivity
The reflectivity is calculated using the Fresnel equations and the analytic formula given by V. G. Kohn in Phys. Stat. Sol. (b) 187, 61 (1995).
Material
The chemical formula is required here. Note that this is case sensitive (e.g. CO for Carbon Monoxide vs Co for Cobalt).
Density
If a negative value is entered, the chemical formula is checked against a list of some common materials. If no match is found then the density of the first element in the formula is used.
Grazing Angle
In keeping with the standard notation for the x-ray region the incidence angle is measured relative to the surface (NOT the surface normal).
Polarization
Pol = 1 corresponds to s-polarization (electric field perpendicular to the plane of incidence). Pol=-1 corresponds to p-polarization (electric field in the plane of incidence). Pol=0 for unpolarized radiation.
Interdiffusion
Interdiffusion/roughness is modeled using the Nevot-Croce factor which multiplies the reflection coefficient of each interface. This assumes an error function profile for the interface with the specified rms thickness.
Output
A GIF plot is generated for viewing the results. For numerical values, follow the link above the GIF plot to an ASCII text file. For a nice looking printed copy, you might try using the EPS file.