In-situ x-ray observation of molecular structure in organic thin films during evaporation process by total reflection in־plane x-ray diffractometer

The in-plane X-ray diffractometer equipped with a vacuum evaporation apparatus was newly developed utilizing the total reflection phenomenon. The measuring system was applied to conduct an in-situ observation of the crystal growth and structural changes in the n-C₃₃H₆₈ molecules during an evaporation process. The results revealed that a certain amount of molecules in the as-evaporated films orient their (010) planes parallel to the surface of the SiO₂ substrate. Moreover, the integrated intensity of the 110 reflection showed variation in the thickness dependence, suggesting that the molecular orientation altered as the interaction between the substrate and the adsored molecules became weaker.