Discrete charging effects in gold nanoclusters grown on self-assembled monolayers

Abstract

Single electron charging effects were observed for gold nanoclusters grown on octanedithiol self-assembled monolayers by scanning tunneling microscopy and X-ray photoelectron spectroscopy (XPS). Strong interaction of gold with the terminal sulfur atoms of dithiol molecules on Au(111) suppresses effectively the penetration of deposited gold atoms through the dithiol layer and results in the formation of uniform metal nanoclusters. Decoupling of the clusters from Au(111) by the octanedithiol layer and the small self-capacitance of the nanoclusters realize the observation of the Coulomb blockade in scanning tunneling spectroscopy and the Au 4f core level shifts in XPS at room temperature. Both phenomena originate from a common physics, the Coulomb energy of charged particles.

Self-Assembly of Alkanedithiols on Au(111) from Solution: Effect of Chain Length and Self-Assembly Conditions

“…This leads to formation of dithiol bridges and allows attachment of some extra dithiol molecules, although measurements as a function of immersion time described here did not yield results that would be compatible with formation of progressively thicker multilayers as reported elsewhere by some authors . The extra charge in the reductive desorption measurements, the marked shift in the electrodesorption potential, and the presence of an excess of strongly bonded molecules with S 2p signal at 163.5 eV support disulfide formation at the SAM as already reported. , It should be noted that similar S 2p XPS spectra with large 163 eV contribution have been reported for octanedithiol SAMs on Au (111) prepared from ethanolic solutions, although the possible presence of disulfide was not discussed …”

“…31,42 It should be noted that similar S 2p XPS spectra with large 163 eV contribution have been reported for octanedithiol SAMs on Au (111) prepared from ethanolic solutions, although the possible presence of disulfide was not discussed. 52 Now, we discuss the formation of disulfide bridges at the free SH groups of the molecules in the standing-up phase when they are prepared by procedure I. It has been reported that the formation of disulfide bonds between adjacent adsorbed dithiolate molecules at a compact monolayer requires a rotation of 180°o f one of the alkyl chains with respect to the other, a process that becomes more difficult as the number of C atoms in the hydrocarbon chain increases.…”

Unique Electron-Transfer-Mediated Electrochemiluminescence of AuPt Bimetallic Nanoclusters and the Application in Cancer Immunoassay

“…The high-resolution XPS spectra of Au 4f and Pt 4f bands were shown in Figure 2B,C. The two characteristic peaks around 84.0 and 87.7 eV demonstrated the existence of Au (0) within GSH-Au 2.5 Pt NCs [46][47][48][49]. Two characteristic peaks around 72.3 and 75.6 eV appearing in the XPS spectrum of Pt 4f indicated Pt (II) valence dominated within GSH-Au 2.5 Pt NCs [50][51][52].…”

Probing the 2D-to-3D structural transition in gold clusters with a single sulfur atom: AuxS0,±1 (x = 1–10)

“…24,25 The interactions between thiolateligands and gold are very important in self-assembled monolayers (SAMs) and ligand-protected gold nanoparticles. [26][27][28][29][30][31][32][33][34] Apart from the importance of Au-S interactions in the eld of nanoelectronics, another interesting aspect of Au-S interactions is the small difference between their electronegativity, the values of Au and S are 2.54 and 2.58, respectively, despite the fact that Au is a metal, while S is a nonmetal.…”