Fabrication of Langmuir-Blodgett films of β-carotene by flow-orientation

Using the Langmuir-Blodgett (LB) method together with the flow-orientation technique which controls the flow of a film material on the subphase, we successfully fabricated a well-ordered film of beta-carotene. The surface pressure-area isotherm suggested that beta-carotene in a Langmuir monolayer oriented perpendicular to the water surface. The flow-orientation method enhanced the molecular orientation in the monolayer. X-ray diffraction patterns indicated that the orientation of beta-carotene in the LB films correlates with the number of layers. The films with five and nine layers yielded tilt angles of 55 degrees and 40 degrees, respectively. Fourier-transform infrared spectroscopy revealed that ionone rings of beta-carotene in the LB film orient perpendicular to the gold substrate.