Relative conductances of alkaneselenolate and alkanethiolate monolayers on Au{111}.
The electronic properties of alkanethiolate [CH3(CH2)nS-, n = 9 and 11] and alkaneselenolate [CH3(CH2)nSe-, n = 9 and 11] self-assembled monolayers on Au{111} have been quantitatively compared. Simultaneously acquired apparent tunneling barrier height (ATBH) and scanning tunneling microscopy (STM) images reveal that alkanethiolate molecules have a lower barrier to tunneling, and therefore a higher conductance than alkaneselenolates of the same alkyl chain length. Molecular and contact conductance differences were elucidated by using observed STM topographic tunneling height differences between the analogous species. This apparent topographic difference combined with comparative ATBH data indicate that the observed decrease in conductance for alkaneselenolates compared to alkanethiolates originates exclusively from the Au-chalcogenide physical, chemical, and electronic contact.
Monnell
Jason D
JD
Departments of Chemistry and Physics, 104 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802-6300, USA.
Stapleton
Joshua J
JJ
Dirk
Shawn M
SM
Reinerth
William A
WA
Tour
James M
JM
Allara
David L
DL
Weiss
Paul S
PS