Simultaneous analysis of total reflection x-ray diffraction and fluorescence from copper-phthalocyanine thin films during evaporation process

A newly developed X-ray measuring system, capable of simultaneously conducting total-reflection X-ray diffraction (TXRD) and total-reflection X-ray fluorescence (TXRF) analyses, was utilized to follow the adsorption and structural changes in copper phthalocyanine (CuPc) thin films during an evaporation process. The intensities of Cu Kα fluorescent X-rays provided precise data on the amount of CuPc molecules adsorbed on the substrate of SiO₂, and thus the difference in adsorption coefficient of CuPc molecules on the SiO₂substrate and the oscillator surfaces of Ag could be evaluated in the first place. Moreover, by combining these fluorescent data with the diffraction data we could follow the exact changes of molecular orientation with the increase of film thickness. The data on the film thickness variations of the X-ray profiles revealed that the structural change in the CuPc molecular crystal occurred at about 9 nm thickness of the evaporated film.