Surface-balance, ellipsometry, and optical second-harmonic-generation techniques are employed to investigate the phase transitions of liquid-crystal 4’-n-octyl-4-cyanobiphenyl films on an air-water interface. We have found, for the first time, a distinctive first-order phase transition between a stable monolayer phase and a stable 3-layer phase of the liquid-crystal film.

• Received 16 April 1992

DOI:https://doi.org/10.1103/PhysRevLett.69.474