Thermal Behavior of One-Layer Langmuir-Blodgett Films of 2-Pentadecyl7,7,8,8-Tetracyanoquinodimethane Studied by Ultraviolet-Visible and Infrared Spectroscopies

摘要

Thermal Behavior of one-layer Langmuir-Blodgett(LB) films of 2-pentadecyl-7,7,8,8-tetracyanoquinodimethane(pentadecyl-TCNQ) has been investigated by use of infrared (IR)and ultraviolet-visible (UV-Vis) spectroscopies. An IRtransmission spectrum of the film shows gradual temperature-dependent changes below the melting point of the film, and thengives dramatic spectral changes near the melting point.Temperature-dependent UV-Vis spectral changes of the filmindicate that the morphological changes occur in domains of thefilm, and that absorption bands in the 320-560 nm region arisingfrom the #pi#-#pi#* transition of the chromophore consist of atleast three components due to different forms of chromophoreaggregation. More active state of the alkyl-chain, hexagonal state,seems to be a trigger for the morphological changes in the domains.