A QUANTITATIVE ELECTRON-SPIN-RESONANCE LINE-SHAPE STUDY OF THE LOCAL MOTION IN THE MICELLAR AND LIQUID-CRYSTALLINE LAMELLAR PHASES OF THE OLEOYLLYSOLECITHIN WATER-SYSTEM
Zc. Liang et al., A QUANTITATIVE ELECTRON-SPIN-RESONANCE LINE-SHAPE STUDY OF THE LOCAL MOTION IN THE MICELLAR AND LIQUID-CRYSTALLINE LAMELLAR PHASES OF THE OLEOYLLYSOLECITHIN WATER-SYSTEM, The Journal of chemical physics, 99(9), 1993, pp. 7098-7107
The experimental electron-spin resonance (ESR) line shapes of the mice
llar (L1) and lamellar (L(alpha) phases of the binary system 1-oleoyl-
sn-glycero-3-phosphocholine (O1LPC)/water have been interpreted quanti
tatively using a two-dynamic (TD) model. This dynamic model comprises
the local dynamics of Freed's model [J. Chem. Phys. 55, 5270 (1971); 5
8, 3185 (1973); 77, 3915 (1982)] and a second Brownian motion referrin
g to the combined effect of the micellar reorientation and the transla
tional motion of the amphiphile molecule along the micellar surface. W
ith this model, we focus our attention on a comparison of the local dy
namics between the L1 and L(alpha), phases. It is found from the TD mo
del that the local ordering (lambda) and dynamics (tau(perpendicular-t
o)) of the L1 phase change compared with those of the L(alpha) phase a
ccording to lambda(L1) > lambda(L(alpha)) and tau(perpendicular-to) (L
1) < tau(perpendicular-to) (L(alpha)). The observed lower local orderi
ng in the lamellar phase compared with that in the micellar phase may
be interpreted in terms of the different packing constraints of the O1
LPC molecule in the two phases.