Aspects of Langmuir-Blodgett trough design: computerization, surface pressure measurement, unevenness of motion, generated vibrations

Abstract

Some factors important to Langmuir-Blodgett film quality like vibrations generated within the trough, unevenness of motion of the barrier or substrate holder, control of constant pressure during deposition are evaluated. It is shown that the addition of analogue devices to the computer control can greatly improve trough performance. Vibrations in the frequency range from 0 to 100 Hz can be cut down to an acceleration amplitude as low as 0.02 × 10 −3 m s −2. A novel translational unit design is presented by which both amplitude and frequency of vibrations can be controlled. The unevenness coefficient strongly depends on the construction of the drive unit and varies from 15 to 50% for different module designs. Integration time below 0.3 s and data acquisition rate above 10 readings per second are recommended for precise surface pressure maintenance.