AVS 51st International Symposium
    Surface Science Monday Sessions
       Session SS-MoP

Paper SS-MoP17
Spontaneous Molecular Row Formation of 9,10-Thiolated Anthracene on Cu(111)

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: K.-Y. Kwon, University of California, Riverside
Authors: K.-Y. Kwon, University of California, Riverside
X. Lin, University of California, Riverside
G. Pawin, University of California, Riverside
K. Wong, University of California, Riverside
B.V. Rao, University of California, Riverside
L. Bartels, University of California, Riverside
Correspondent: Click to Email
Self-assembled monolayers (SAMs) have been the subject of intense research for the recent two decades due to the fact that they can be used to dramatically modify the chemical, physical and electronic properties of surfaces. Thiolate-SAMs offers powerful opportunities for fundamental studies of electron transport, single molecule devices, control of surface wettability, etc. It is known that both alkane- and arene-thiols stand close to upright on the surface at high coverage. Here, we report on the adsorption structure of 9,10-(diacetylthio)anthracene on Cu(111) at low temperatures in ultrahigh vacuum using scanning tunneling microscopy (STM). Before deprotection of the acetyl group, the molecules are mobile even at 80K. Upon heating of the sample in excess of 180K, the acetyl protection group is removed from the thiol and desorbs, as ascertained by thermally programmed desorption experiments. After renewed cooling of the sample to 80K, we find spontaneous assembly of extended molecular rows of dithioantracene molecules. Studies of the attachment and disattachment of diffusing molecules to the end of the rows at various cryogenic temperatures indicate a barrier of 14.8KJ/mol for this process. At increased coverages the antracenes form extended island with a rectangular unit cell.