A spectroscopic study of thiol layers prepared by contact printing

Films of hexadecane thiol on gold prepared by contact printing with a stamp of polydimethylsiloxane were investigated by IR–VIS sum frequency generation SFG., IR spectroscopy, X-ray photoelectron spectroscopy XPS., and contact angle measurements. The contact time was up to 60 s and the pressure ranged from 1 to 6 bar. SFG, as a method directly sensitive to molecular conformation, reveals a significantly higher degree of disorder in stamped films compared to monolayers prepared by immersion. Correspondingly, contact angle measurements yield a lower advancing contact angle and a higher hysteresis. XPS analysis shows that residues of the stamping material are left on the surface. q1999 Elsevier Science B.V. All rights reserved.