Partial dark-field microscopy for investigating domain structures of double-layer microsphere film.

Joon Heon Kim,Jung Su Park

doi:10.1038/srep10157

Abstract

A lateral dislocation in a double-layer microsphere film is very difficult to identify because the constituent domains have the same two-dimensional crystalline orientation. Orientation-sensitive optical techniques cannot resolve this issue. Here, we demonstrate that partial dark-field (pDF) optical microscopy can be very effective in identifying this type of domain boundary and dislocation of a close-packed microsphere double-layer. Using the hexagonal symmetry of the close-packed microsphere film and the light-focusing property of microspheres, the partially blocked dark-field condenser can provide much higher contrast than other optical microscopy modes can in identifying the laterally dislocated domains. The former can also distinguish domains with different crystalline orientation by rotating the pDF stop. The simplicity of the pDF mode will make it an ideal tool for the structural study of close-packed double-layer microsphere films.

Highlights

A lateral dislocation in a double-layer microsphere film is very difficult to identify because the constituent domains have the same two-dimensional crystalline orientation
Close-packed microsphere films have been intensively studied in recent years because of their possible application as templates for nanostructures or photonic crystal structures[1,2,3,4,5]
One of the simplest methods to identify the crystalline structure of the microsphere film is the identification of the position of each microsphere by optical microscopy

Summary

Introduction

A lateral dislocation in a double-layer microsphere film is very difficult to identify because the constituent domains have the same two-dimensional crystalline orientation. Because upper-layer microspheres should be located on the hollows formed by three contacting microspheres of the lower layer in the close-packed conformation, two different stacking conformations of the same two-dimensional crystalline orientation are possible (Fig. 1).

Results

Conclusion