Nonionic Fluorosurfactant Zonyl FSN self-assembly on Au(111) is investigated with scanning tunneling microscopy under ambient conditions. STM reveals that the FSN forms SAMs on Au(111) with very large domain size and almost no defects. A (root 3 x root 3)R30 degrees arrangement of the FSN SAM on Au(111) is observed. The SAMs show excellent chemical stability and last for at least a month in atmospheric conditions. The structure and stability of the FSN SAMs are compared with those of alkanethiols SAMs. It is expected that FSN may serve as a new kind of molecule to form SAMs for surface modification, which would benefit wider applications for various purposes.