Off-Specular scattering

Off-specular scattering from a monodisperse distribution of long boxes.

  • The sample is made of very long boxes with length equal to $1000$ nm, width $20$ nm and height $10$ nm.
  • The particles are distributed along a one-dimensional lattice with a lattice spacing of $100$ nm in the $x$-direction.
  • The particles are rotated around the $z$-axis by $90^{\circ}$ so that their “infinite” dimension is parallel to the $y$-direction.
  • The incident wavelength is equal to 0.1 nm.
  • The output intensity is the result of an average over $\varphi_i$ comprised between $-1^{\circ}$ and $1^{\circ}$ and of a scan of $\alpha_i$ and $\alpha_f$ between $0^{\circ}$ and $10^{\circ}$.

Note:

The two-dimensional output intensity is plotted as a function of $\alpha_i$ and $\alpha_f$.

Real-space model

Intensity image

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#!/usr/bin/env python3
"""
Long boxes at 1D lattice, ba.Offspec simulation
"""
import bornagain as ba
from bornagain import ba_plot as bp, deg, nm

phi_f_min, phi_f_max = -1, 1.0
alpha_f_min, alpha_f_max = 0, 10.0
alpha_i_min, alpha_i_max = 0, 10.0  # incoming beam


def get_sample():
    """
    Returns a sample with a grating on a substrate,
    modelled by infinitely long boxes forming a 1D lattice.
    """

    # Define materials
    material_Particle = ba.RefractiveMaterial("Particle", 0.0006, 2e-08)
    material_Substrate = ba.RefractiveMaterial("Substrate", 6e-06, 2e-08)
    material_Vacuum = ba.RefractiveMaterial("Vacuum", 0, 0)

    # Define form factors
    ff = ba.Box(1000*nm, 20*nm, 10*nm)

    # Define particles
    particle = ba.Particle(material_Particle, ff)
    particle_rotation = ba.RotationZ(90*deg)
    particle.setRotation(particle_rotation)

    # Define interference functions
    iff = ba.Interference1DLattice(100*nm, 0)
    iff_pdf = ba.Profile1DCauchy(1e6*nm)
    iff.setDecayFunction(iff_pdf)

    # Define particle layouts
    layout = ba.ParticleLayout()
    layout.addParticle(particle)
    layout.setInterference(iff)
    layout.setTotalParticleSurfaceDensity(0.01)

    # Define layers
    layer_1 = ba.Layer(material_Vacuum)
    layer_1.addLayout(layout)
    layer_2 = ba.Layer(material_Substrate)

    # Define sample
    sample = ba.MultiLayer()
    sample.addLayer(layer_1)
    sample.addLayer(layer_2)

    return sample


def get_simulation(sample):
    """
    Returns an off-specular simulation with beam and detector defined.
    """
    n = bp.simargs['n']
    simulation = ba.OffspecSimulation(sample)
    simulation.detector().setDetectorParameters(20, phi_f_min*deg, phi_f_max*deg, n,
                                                alpha_f_min*deg, alpha_f_max*deg)
    # define the beam with alpha_i varied between alpha_i_min and alpha_i_max
    alpha_i_axis = ba.FixedBinAxis("alpha_i", n, alpha_i_min*deg,
                                   alpha_i_max*deg)
    simulation.setBeamParameters(0.1*nm, alpha_i_axis, 0)
    simulation.beam().setIntensity(1e9)
    return simulation


if __name__ == '__main__':
    bp.parse_args(sim_n=200, intensity_min=1)
    sample = get_sample()
    simulation = get_simulation(sample)
    result = simulation.simulate()
    bp.plot_simulation_result(result)
Examples/varia/OffspecSimulation.py