Vacuum-deposited films of meso-2,4-di(N-carbazolyl)pentane. In situ fluorescence observation of the deposition process and fluorescence and morphological characteristics of the films

Abstract

The deposition processes of meso-2,4-di(N-carbazolyl)pentane have been investigated by measuring in situ fluorescence spectra during deposition on hydrophilic and hydrophobic quartz substrates. Excimer fluorescence was observed at the initial stage of deposition, and its intensity ratio to monomer fluorescence changed with the progress of deposition, depending upon the nature of the substrate and the temperature. Polarizing, optical and fluorescence microscopies of deposited films were carried out after taking the samples out of the deposition 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 for 1 month. The initial aggregates were amorphous, but the fractal aggregates were crystalline. This behaviour is discussed in terms of interactions between the substrate and the compound.