Study on the molecular distribution of organic composite films by combining photoemission spectroscopy with argon gas cluster ion beam sputtering

X-ray/ultraviolet photoelectron spectroscopy (XPS/UPS) and argon gas cluster ion beam (GCIB) sputtering were combined to directly study the molecular configurations of organic composite films consisting of more than two different materials. In contrast to Ar ion sputtering, Ar GCIB sputtering does not critically distort the chemical states and atomic compositions of organic materials, thereby enabling the chemical structures of uncontaminated bulk regions and air-exposed surface regions of organic materials to be precisely examined. Using this combination, the molecular configurations of single-wall and multiwall carbon nanotube (SWNT and MWCNT) films, composed of corresponding CNTs and surfactants, could be specifically characterized based on the chemical state transitions in the C 1s core level depth profiles. Further, the XPS/UPS spectra showed variations in the chemical states with increasing sputtering time, which were fully consistent with the surface morphologies observed in the high-resolution atomic force microscopy and high-resolution secondary electron microscopy images. Hence, we believe that combining XPS/UPS with Ar GCIB sputtering can be an excellent method for investigating the molecular distributions of organic composite films.