Physical and electronic structure of p-sexiphenyl on Au(111)

The electronic structure, adsorption energies, and molecular ordering of p-sexiphenyl (p-6P) films on Au(111) have been investigated with ultraviolet photoemission spectroscopy, temperature programmed desorption (TPD), and scanning tunneling microscopy (STM). Films up to 50 Å of p-6P were studied and a substantial interface dipole was measured (0.73 eV). Two distinct p-6P binding environments with heats of adsorption of 126 and 143 kJ/mol were observed using TPD. An unusual surface structure that contains alternating face and edge-on p-6P molecules was observed using STM. A model similar to the bulk p-6P structure with alternating face and edge-on interactions is proposed.