TY - JOUR
T1 - The structure of a Langmuir monolayer of methyl eicosanoate as determined by x-ray diffraction and Brewster angle microscopy
AU - Foster, W. J.
AU - Shih, M. C.
AU - Pershan, P. S.
N1 - Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 1996/8/22
Y1 - 1996/8/22
N2 - Relaxed Langmuir monolayers of methyl eicosanoate were studied using Brewster angle microscopy (BAM) and grazing incidence x-ray diffraction (GIXD). The structure of the various phases in this system was determined and compared to previous isotherm and microscopy measurements. At low pressure and low temperature, a crystalline phase with tilt toward nearest neighbor, I(L″2), is observed. At a temperature of ∼ 14 °C and low pressure there is a transition to a phase with tilt toward next-nearest neighbor, F(L′2). Finally, as the temperature continues to be raised at low pressure, there is a transition to a phase where the two F(L′2) peaks have the same values of Qxy, here called the τ phase, with a Rotator IV-like structure. At high pressure and low temperature, an untilted, orthorhombic phase, U′ (CS), is observed. As the temperature is increased, a second untilted, orthorhombic phase, U(S), is observed, beginning at ∼ 12 °C. Above 21 °C and at high pressure, a Rotator-II-like phase is seen, with an undistorted, untilted structure. Finally, results from BAM measurements are used to monitor the texture of the film in the different phases.
AB - Relaxed Langmuir monolayers of methyl eicosanoate were studied using Brewster angle microscopy (BAM) and grazing incidence x-ray diffraction (GIXD). The structure of the various phases in this system was determined and compared to previous isotherm and microscopy measurements. At low pressure and low temperature, a crystalline phase with tilt toward nearest neighbor, I(L″2), is observed. At a temperature of ∼ 14 °C and low pressure there is a transition to a phase with tilt toward next-nearest neighbor, F(L′2). Finally, as the temperature continues to be raised at low pressure, there is a transition to a phase where the two F(L′2) peaks have the same values of Qxy, here called the τ phase, with a Rotator IV-like structure. At high pressure and low temperature, an untilted, orthorhombic phase, U′ (CS), is observed. As the temperature is increased, a second untilted, orthorhombic phase, U(S), is observed, beginning at ∼ 12 °C. Above 21 °C and at high pressure, a Rotator-II-like phase is seen, with an undistorted, untilted structure. Finally, results from BAM measurements are used to monitor the texture of the film in the different phases.
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U2 - 10.1063/1.472185
DO - 10.1063/1.472185
M3 - Article
AN - SCOPUS:0030211933
SN - 0021-9606
VL - 105
SP - 3307
EP - 3315
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 8
ER -