Depth resolved grazing incidence scattering from the solid-liquid interface

TL;DR

This study uses grazing incidence small angle neutron scattering with broad wavelength distribution to analyze the near-surface structure of polymer micelles on silicon, revealing surface energy-dependent ordering.

Contribution

It introduces a method combining grazing incidence scattering with broad wavelength distribution to resolve depth-dependent structures in a single measurement.

Findings

Near-surface structure varies with surface coating.

Higher surface energy enhances ordering near the surface.

Bulk-like ordering occurs further from the surface.

Abstract

We have applied small angle scattering in grazing incidence beam geometry on a time-of-flight neutron instrument. Due to the broad wavelength distribution provided for a specific incident beam angle the penetration depth of the neutron beam is varied over a broad range in a single measurement. The near surface structure of polymer micelles close to silicon substrates with distinct surface energy is resolved. It is observed that the very near-surface structure strongly depends on the surface coating whereas further away from the surface bulk like ordering is found. A more pronounced ordering is found close to surfaces with high surface energy.