Plasma Beam Alignment of Liquid Crystals on the Bare Glass: Modification of Surface Chemical Composition

Abstract

X-ray Photoelectron Spectroscopy was applied to study the chemical composition of the modified glass surfaces by the flux of accelerated Ar or Ar/H₂ plasma in order to clarify mechanisms of liquid crystal (LC) alignment on these surfaces. It was established that the surface of prinstine glass exposed to air contains carbonaceous contamination layer consisting of about 50% of aliphatic/aromatic carbon and about 50% of C–O moieties of various types. Plasma processing results in partial ablation of this layer and modification of its chemical composition. This suggests that LCs are actually being aligned by the plasma modified carbonaceous layer rather than by a pure glass.

Keywords:

• Alignment
• carbonaceous layers
• liquid crystal
• plasma treatment
• XPS

Acknowledgment

Part of these studies was conducted under the project 10/07-H (NASU, Ukraine).

Notes

¹The elements presented in glass in small quantity (B, Ca, etc.) were below detection limit.

^a The asterisk designates the atom for which the binding energy is estimated.