ISSN:
0377-0486
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
By combining a high-sensitivity charge-coupled device detector with the total reflection technique, Raman spectra in the CH stretching region were recorded for thin Langmuir-Blodgett (LB) films of dipalmitoylphosphatidylcholine (DPPC) prepared at various surface pressures encompassing the plateau region of its surface pressure-area isotherm. Surface-pressure dependences of the lateral packing and the conformational order are discussed using the peak intensity ratio between the 2880 and 2850 cm-1 bands and that between the 2935 and 2850 cm-1 bands. The results indicate that at higher surface pressures above the plateau, the hydrocarbon chains of DPPC are tightly packed and highly oriented with the all-trans conformation. Below the plateau, however, the chains are disordered because of the increased number of the gauche conformers. The loosely packed hydrocarbon chains observed for the LB films deposited at lower surface pressures are gradually reoriented with time to form stable and highly ordered aggregates.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jrs.1250221206
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