ISSN:
0142-2421
Keywords:
Langmuir films
;
porphyrin surface orientation
;
second harmonic generation
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Physics
Notes:
Optical second harmonic generation is used to investigate the characteristics of a Langmuir film of hematoporphyrin IX dimethyl ester on water. Interfacial molecular orientation is determined by the construction of a system response function based on general and consistent assumptions concerning the distribution of second-order non-linear hyperpolarizabilities and the second harmonic intensity variation for compressed and expanded versions of the film. Two dominant average hyperpolarizability axes are observed for the individual molecules making up the film. Further, it is found that the molecules tend to align towards the vertical as the film is compressed from the maximum mean molecular area of 130 Å to the minimum mean molecular area of 70 Å2. The molecular tilt angle varies from 44° under maximum compression to 71° under full expansion. These results show good quantitative agreement with previous investigations of Langmuir films of similar molecules. © 1997 by John Wiley & Sons, Ltd.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
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