CHANGE OF ELECTRONIC ABSORPTION-SPECTRA OBSERVED THROUGH HEATING EVAPORATED THIN-FILMS OF A DIACETYLENE COMPOUND

A vapor-deposited thin film of N-[4'-(5'-hydroxypenta-1 '',3 ''-diynyl )-benzylidene]-4-octyloxyaniline, which is one of the diacetylene comp ounds, demonstrated a drastic change of its electronic absorption spec trum characterized by the absorption edge being expanded to the near-i nfrared region, associated with heating its substrate above 100 degree s C. X-ray diffraction patterns of the film revealed that there are th ree different stages for the film at temperatures elevated through hea ting. As it has been confirmed that the molecule concerned suffers no chemical change through the heat treatments, those observed phenomena can be understood to be induced by a characteristic change in intermol ecular electronic interaction via modification of molecular aggregatio n forms caused by substrate heating.