Real-time observation on surface diffusion and molecular orientations for phthalocyanine thin films at nanometer spacial resolution

Baba, Yuji  ; Sekiguchi, Tetsuhiro  ; Shimoyama, Iwao   ; Honda, Mitsunori   ; Hirao, Norie; Narita, Ayumi; Deng, J.

The morphology, electronic structure and ordering for micropatterns of silicon phthalocyanine thin films on gold have been investigated at nanometer scale by photoelectron emission microscopy (PEEM) excited by polarized soft X-rays from synchrotron light source. The incident angle dependences of the X-ray absorption fine structure (XANES) spectra at the silicon K-edge revealed that the molecules of 5-layered films are lying nearly flat on the surface. Clear image of the micropattern was observed by PEEM at room temperature, while the surface diffusion was observed upon heating. On the basis of the photon-energy dependences of the brightnesses in the PEEM images, it was found that the molecules diffusing to the fresh gold surface rather stand-up at 240C. The observed changes in the molecular orientations at nanometer domains are discussed on the basis of the strengths of the molecular-molecular and molecular-surface interactions.