TY - JOUR
T1 - Length dependence of charge transport in nanoscopic molecular junctions incorporating a series of rigid thiol-terminated norbornylogs
AU - Beebe, Jeremy M.
AU - Engelkes, Vincent B.
AU - Liu, Jingquan
AU - Gooding, J. Justin
AU - Eggers, Paul K.
AU - Jun, Yongseok
AU - Zhu, Xiaoyang
AU - Paddon-Row, Michael N.
AU - Frisbie, C. Daniel
PY - 2005/3/24
Y1 - 2005/3/24
N2 - Four tetrathiol-terminated norbornane homologues were synthesized and self-assembled monolayers (SAMs) of these molecules were formed on Au via adsorption from CH 2Cl 2. SAMs were characterized structurally via spectroscopic ellipsometry (SE), reflection-absorption infrared spectroscopy (RAIRS), Rutherford backscattering spectrometry (RBS), and X-ray photoelectron spectroscopy (XPS). Results of these analyses show that the rigid norbornylogs form monolayers that have a surface coverage slightly lower than that of alkanethiols, and that they exhibit a nonmonotonic dependence of film thickness on molecular length. Nanoscale molecular junctions incorporating these SAMs were formed and characterized electrically using conducting probe atomic force microscopy (CP-AFM). The resistances of these junctions scale exponentially with the contour length of the molecules, with β = 0.9 Å -1, consistent with a nonresonant tunneling mechanism. Further, the resistance of norbornyl SAMs correlates well with the resistance of alkanedithiol SAMs of similar length, suggesting that the norbornyl molecules form sulfur-metal bonds on both ends of the junction.
AB - Four tetrathiol-terminated norbornane homologues were synthesized and self-assembled monolayers (SAMs) of these molecules were formed on Au via adsorption from CH 2Cl 2. SAMs were characterized structurally via spectroscopic ellipsometry (SE), reflection-absorption infrared spectroscopy (RAIRS), Rutherford backscattering spectrometry (RBS), and X-ray photoelectron spectroscopy (XPS). Results of these analyses show that the rigid norbornylogs form monolayers that have a surface coverage slightly lower than that of alkanethiols, and that they exhibit a nonmonotonic dependence of film thickness on molecular length. Nanoscale molecular junctions incorporating these SAMs were formed and characterized electrically using conducting probe atomic force microscopy (CP-AFM). The resistances of these junctions scale exponentially with the contour length of the molecules, with β = 0.9 Å -1, consistent with a nonresonant tunneling mechanism. Further, the resistance of norbornyl SAMs correlates well with the resistance of alkanedithiol SAMs of similar length, suggesting that the norbornyl molecules form sulfur-metal bonds on both ends of the junction.
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U2 - 10.1021/jp044630p
DO - 10.1021/jp044630p
M3 - Article
C2 - 16863186
AN - SCOPUS:15744368800
SN - 1520-6106
VL - 109
SP - 5207
EP - 5215
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 11
ER -