Vacuum ultraviolet optical analysis of spin-cast chitosan films modified by succinic anhydride and glycidyl phenyl ether

• Published in: Surface and interface analysis 2007-09, Vol.39 (9), p.747-751
• Main Authors: Nosal, W. H., Thompson, D. W., Tiwald, T. E., Sarkar, S., Subramanian, A., Woollam, J. A.
• Format: Article
• Language: English
• Subjects: chitosan; Condensed matter: electronic structure, electrical, magnetic, and optical properties; ellipsometry; Exact sciences and technology; optical constants; Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity); Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics; spectroscopy; vacuum ultraviolet
• ISSN: 0142-2421; 1096-9918
• DOI: 10.1002/sia.2581

Optical properties of spin‐cast chitosan films were determined in the vacuum ultraviolet (VUV) through visible regions of the spectrum using spectroscopic ellipsometry. The onset of absorption in the ultraviolet was determined for chitosan films modified with succinic anhydride (SA) and glycidyl phenyl ether (GPE). This absorption was accounted for by including Gaussian and Tauc–Lorentz shaped oscillators in the optical model. VUV through visible optical constants were determined for these modified films, as well as for immunoglobulin G (IgG) attached to GPE‐modified samples. Several resonant oscillator structures exhibit greatly differing oscillator parameters for the as‐deposited, as well as SA‐ and GPE‐modified films. These in‐plane and out‐of‐plane oscillator strengths, energy positions, and broadening were determined and tabulated, and their chemical origins identified. A phenyl resonant π‐bond at approximately 6.3 eV was observed for the GPE‐modified sample. This was not present in the bare chitosan data. GPE contains a phenyl group in the molecule and absorption due to it is clearly identified. Clarity of data after surface chemical modification is due to the high surface sensitivity of VUV ellipsometry. Copyright © 2007 John Wiley & Sons, Ltd.