Interference 2D centered square lattice

Scattering from cylinders positioned in a squared centered lattice.

  • The particles are cylinders with radii and heights of $3$ nm.
  • Their spatial distribution is composed of two square lattices (lattice length $l$), shifted by half a lattice length in both directions:
  • The first square lattice is centered at the origin, with a lattice length of $25$ nm.
  • The second one, with the same lattice spacing and the same type of particles at its nodes is initialized at $x = y = l/2 = 12.5$ nm.
  • The lattices’ base vectors are parallel to the axes of the reference cartesian frame.
  • The wavelength is equal to 0.1 nm.
  • The incident angles are $\alpha_i = 0.2 ^{\circ}$ and $\varphi_i = 0^{\circ}$.

Real-space model

Intensity image

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
#!/usr/bin/env python3
"""
2D lattice with disorder, centered square lattice
"""
import bornagain as ba
from bornagain import ba_plot as bp, deg, nm, R3
import matplotlib.pyplot as plt


r = 3*nm  # particle radius
a = 25*nm  # lattice constant


def get_sample():
    """
    A sample with cylinders on a substrate,
    forming a 2D centered square lattice
    """

    # Materials
    material_particle = ba.RefractiveMaterial("Particle", 0.0006, 2e-08)
    material_substrate = ba.RefractiveMaterial("Substrate", 6e-06, 2e-08)
    vacuum = ba.RefractiveMaterial("Vacuum", 0, 0)

    # Particles
    ff = ba.Cylinder(r, r)
    particle_1 = ba.Particle(material_particle, ff)
    particle_2 = ba.Particle(material_particle, ff)
    particle_2.translate(R3(a/2, a/2, 0))

    # Composition of particles at specific positions
    basis = ba.Compound()
    basis.addComponent(particle_1)
    basis.addComponent(particle_2)

    # 2D lattices
    lattice = ba.SquareLattice2D(a, 0*deg)

    # Interference functions
    iff = ba.Interference2DLattice(lattice)
    iff_pdf = ba.Profile2DCauchy(48*nm, 16*nm, 0)
    iff.setDecayFunction(iff_pdf)

    # Particle layouts
    layout = ba.ParticleLayout()
    layout.addParticle(basis)
    layout.setInterference(iff)
    layout.setTotalParticleSurfaceDensity(0.0016)

    # Layers
    layer_1 = ba.Layer(vacuum)
    layer_1.addLayout(layout)
    layer_2 = ba.Layer(material_substrate)

    # Sample
    sample = ba.Sample()
    sample.addLayer(layer_1)
    sample.addLayer(layer_2)

    return sample


def get_simulation(sample):
    beam = ba.Beam(1e9, 0.1*nm, 0.2*deg)
    n = 200
    detector = ba.SphericalDetector(n, -2*deg, 2*deg, n, 0, 2*deg)
    simulation = ba.ScatteringSimulation(beam, sample, detector)
    return simulation


if __name__ == '__main__':
    sample = get_sample()
    simulation = get_simulation(sample)
    result = simulation.simulate()
    bp.plot_simulation_result(result)
    plt.show()
auto/Examples/scatter2d/Interference2DCenteredSquareLattice.py