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Core-and-shell nanoparticles

Scattering from cuboidal core-shell particles.

  • The sample is made of core-shell particles whose outer and inner shells are boxes with dimensions $L_1 = W_1 = 16$ nm, $H_1 = 8$ nm and $L_2 = W_2 = 12$ nm, $H_2 = 7$ nm, respectively, where $L_i$, $W_i$ and $H_i$ are the length, width and height of box $i$.
  • The smaller box is positioned so that the centres of the bottom faces of both particles coincide.
  • The simulation is run using the Born approximation. There is no substrate and no interference between the different scattered beams.
  • The planar distribution of the particles is diluted and random.
  • The incident wavelength is equal to 0.1 nm.
  • The incident angles are $\alpha_i = 0.2 ^{\circ}$ and $\varphi_i = 0^{\circ}$.

Real-space model

Scattering intensity

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#!/usr/bin/env python3
"""
Core shell nanoparticles
"""
import bornagain as ba
from bornagain import ba_plot as bp, deg, nm


def get_sample():
    """
    A sample with box-shaped core-shell particles on top of air.
    """

    # Materials
    core_color = (0.86, 0.24, 0.18)
    core_mat = ba.RefractiveMaterial("Core", core_color, 6e-6, 2e-8)
    shell_color = (0.25, 0.65, 0.35)
    shell_mat = ba.RefractiveMaterial("Shell", shell_color, 1e-5, 2e-8)

    # Form factors
    ff_1 = ba.Box(12*nm, 12*nm, 7*nm)
    ff_2 = ba.Box(16*nm, 16*nm, 8*nm)

    # Particles
    core = ba.Particle(core_mat, ff_1)
    shell = ba.Particle(shell_mat, ff_2)
    particle = ba.CoreAndShell(core, shell)

    # Sample with particles in vacuum over vacuum substrate
    layer_1 = ba.Layer(ba.Vacuum())
    layer_1.deposit2D(ba.Dilute2D(0.001, particle))
    layer_2 = ba.Layer(ba.Vacuum())

    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, -1*deg, 1*deg, n, 0., 2*deg)
    simulation = ba.ScatteringSimulation(beam, sample, detector)
    return simulation


if __name__ == '__main__':
    sample = get_sample()
    ba.showSample3D(sample, sample_size=120*nm, seed=0)
    simulation = get_simulation(sample)
    result = simulation.simulate()
    bp.plot_datafield(result, unit_aspect=1)
    bp.plt.show()
auto/Examples/scatter2d/CoreShellNanoparticles.py

Validated through an alternative implementation that uses particle composition, Examples/scatter2d/CoreShellNanoparticles2.py .