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Proceedings Paper

Nonlinear optical characterization of aromatic amino acids at the air/water interface: intrinsic probes of protein ordering on surfaces
Author(s): Beth L. Smiley; Viola Vogel
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Paper Abstract

The nonlinear optical properties of the aromatic amino acid residues naturally found in proteins are studied using resonantly enhanced second harmonic generation (SHG) in reflection from the air/water interface. In order to evaluate their potential utility as nonlinear optical probes of peptide and protein organization, tryptophan (Trp), tyrosine, and phenylalanine have been adsorbed from solution to the air/water interface in a model study. The dependence of the theoretically determined tilt angle of the resonantly enhanced 1A->1La transition dipole moment of Trp with respect to the surface normal on the assumed refractive indices of the monolayer is inferred from a SHG nulling measurement. Orientational information cannot be meaningfully deduced for tyrosine or phenylalanine as several transitions are resonantly enhanced for these residues in the near UV. The phases of the second harmonic signals from the surface adsorbed residues in comparison to the reference signal from water are also determined.

Paper Details

Date Published: 21 July 1994
PDF: 9 pages
Proc. SPIE 2125, Laser Techniques for Surface Science, (21 July 1994); doi: 10.1117/12.180869
Show Author Affiliations
Beth L. Smiley, Univ. of Washington (United States)
Viola Vogel, Univ. of Washington (United States)

Published in SPIE Proceedings Vol. 2125:
Laser Techniques for Surface Science
Hai-Lung Dai; Steven J. Sibener, Editor(s)

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