Orientational order study of 4-alkyl-4′-cyanobiphenyl Langmuir films by Maxwell displacement current and optical second harmonic generation measurements

Abstract

Maxwell displacement current (MDC) measurement coupled with second harmonic generation (SHG) measurement was employed for the orientational order study of Langmuir films. 4-alkyl-4′-cyanobiphenyl ( nCB, n=5, 6, 7 and 8) Langmuir films were examined, and the orientational order parameters were determined. The difference in the generation between MDC and SHG was revealed, and was discussed based on the difference in the contribution of nCBs. It is shown that the measurement employed here is very helpful for the orientational study of Langmuir films.