Cosine Ripples in a Rectangular Lattice

Scattering from elongated particles distributed along a two-dimensional rectangular lattice.

  • Each particle has a sinusoidal profile (“Ripple1” form factor) with a length of $100$ nm, a width of $20$ nm and a height of $4$ nm.
  • They are placed along a rectangular lattice on top of a substrate.
  • This lattice is characterized by a lattice length of $200$ nm in the direction of the long axis of the particles and of $50$ nm in the perpendicular direction.
  • The lattice’s base vectors coincide with the reference Cartesian frame.
  • The wavelength is equal to $1.6$ $\unicode{x212B}$.
  • The incident angles are $\alpha_i = 0.3 ^{\circ}$ and $\varphi_i = 0^{\circ}$.

Real-space model

Intensity image

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#!/usr/bin/env python3
"""
Cosine ripple on a 2D lattice
"""
import bornagain as ba
from bornagain import deg, nm


def get_sample():
    """
    Returns a sample with cosine ripples on a substrate.
    The structure is modelled as a 2D Lattice.
    """

    # Define materials
    material_Particle = ba.HomogeneousMaterial("Particle", 0.0006, 2e-08)
    material_Substrate = ba.HomogeneousMaterial("Substrate", 6e-06, 2e-08)
    material_Vacuum = ba.HomogeneousMaterial("Vacuum", 0.0, 0.0)

    # Define form factors
    ff = ba.FormFactorCosineRippleBox(100.0*nm, 20.0*nm, 4.0*nm)

    # Define particles
    particle = ba.Particle(material_Particle, ff)

    # Define 2D lattices
    lattice = ba.BasicLattice2D(200.0*nm, 50.0*nm, 90.0*deg, 0.0*deg)

    # Define interference functions
    iff = ba.InterferenceFunction2DLattice(lattice)
    iff_pdf = ba.FTDecayFunction2DCauchy(160.0*nm, 16.0*nm, 0.0*deg)
    iff.setDecayFunction(iff_pdf)

    # Define particle layouts
    layout = ba.ParticleLayout()
    layout.addParticle(particle, 1.0)
    layout.setInterferenceFunction(iff)
    layout.setWeight(1)
    layout.setTotalParticleSurfaceDensity(0.0001)

    # 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):
    beam = ba.Beam(1.0, 0.16*nm, ba.Direction(0.3*deg, 0*deg))
    detector = ba.SphericalDetector(100, -1.5*deg, 1.5*deg, 100, 0*deg, 2.5*deg)
    simulation = ba.GISASSimulation(beam, sample, detector)
    return simulation


if __name__ == '__main__':
    import ba_plot
    sample = get_sample()
    simulation = get_simulation(sample)
    ba_plot.run_and_plot(simulation)
CosineRipplesAtRectLattice.py