We have used second harmonic generation to directly observe chemical changes in a lipid monolayer. We observed that pK, of phexadecyl aniline at the air/water interface is 3.6& 0.2 versus 5.3 fO.l in the bulk. This fiftyfold increase in acidity is due to the higher free energy of a charged species a
Second harmonic generation from the air/water interface of an aqueous solution of the dipeptide Boc-Trp-Trp
β Scribed by Michael J. Crawford; Steven Haslam; J.M. Probert; Yuri A. Gruzdkov; Jeremy G. Frey
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 431 KB
- Volume
- 230
- Category
- Article
- ISSN
- 0009-2614
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β¦ Synopsis
The air/water interface of aqueous ( &butyloxycarbonyl)-tryptophan-tryptophan ( Boc-Trp-Trp) has been studied by surface second harmonic generation (SHG). The SHG signals obtained with a linearly polarised fundamental indicate a Langmuir-like adsorption isotherm. Wavelength-dependent circularly differential harmonic generation (SHG-CD) was observed together with SHG optical rotation. The SHG signals from the LL and DD enantiomer show equal but opposite dependence on the handedness of the fundamental radiation and the DL diastereoisomer gave rise to a different spectrum.
π SIMILAR VOLUMES
Monolayers of two nitroaniline-terminated amphiphilic compounds that differ from each other only by a methylene group in the hydrocarbon chain arestudied at the air-water interface by optical second harmonic generation and ellipsometry. The nitroanilino groups exhibit significantly different orderin