IN-SITU FLUORESCENCE OBSERVATION OF THE VACUUM-DEPOSITION PROCESS OF 1,3-DI-N-CARBAZOLYLPROPANE AND MORPHOLOGICAL-CHARACTERISTICS OF THE DEPOSITED FILM

The deposition processes of 1,3-di-N-carbazolylpropane (DCzP) have bee n investigated by measuring in situ fluorescence spectra during deposi tion on hydrophilic and hydrophobic quartz substrates. Excimer fluores cence was observed even at the initial stage of deposition, and its in tensity ratio to monomer fluorescence changed with the progress of dep osition, depending upon the nature of the substrate and the temperatur e. The deposition process of DCzP on hydrophilic substrates consisted of four stages, whereas three stages were observed for deposition on h ydrophobic substrates. The fluorescence spectrum of the deposited DCzP film consisted of monomer, partial overlap excimer, and sandwich exci mer fluorescence and was different from that of an amorphous DCzP film prepared by fast evaporation of the solvent. Fluorescence and optical microscopies of deposited films were performed after taking the films out of the vacuum chamber. The deposited molecules formed aggregates on the substrates which were initially spherical but which changed to a fractal-like shape after having been stored in a desiccator. The ini tial aggregates were amorphous, but the fractal-like aggregates were c rystalline. These behaviors were compared with the results of meso-2,4 -di-N-carbazolylpentane presented in our previous work and discussed i n terms of interactions between the substrate and the compound and dif ference in a conformational distribution between these bichromophoric compounds.