Benzenethiol adsorption on Au(111) studied by synchrotron ARUPS, HREELS and XPS

Whelan, Caroline M.; Barnes, Colin; Walker, Christopher; Brown, N. M. D.

doi:10.1016/s0039-6028(99)00181-8

Cited by 116 publications

(90 citation statements)

References 44 publications

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“…UPS/IPES measurements of alkyl thiols on Au 55 yield a HOSO-LUSO gap of 7.85 eV and significantly smaller |E F − LUSO| (∼ 3.35 eV) than |E F − HOSO| (∼ 4.5 eV) (the latter is in good agreement with previously reported |E F − HOSO| for alkyl thiols on Au (∼ 5 eV). 22,56,57 The HOSO-LUSO gap is similar to the gap measured for alkyl chain monolayers on both Si 58,59 and GaAs 60 with different binding groups (Si-C, Si-O-C and GaAs-PO 3 -C), i.e., it is not influenced significantly by binding group and substrate type. The range of the edge-to-edge gap in all examined samples is ∼ (7.1 − 7.8) eV, if the IDIS onset is ignored.…”

Section: Resultssupporting

confidence: 66%

Charge transport across metal/molecular (alkyl) monolayer-Si junctions is dominated by the LUMO level

Yaffe

Scheres

et al. 2012

Phys. Rev. B

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We compare the charge transport characteristics of heavy doped p ++ -and n ++ -Si-alkyl chain/Hg junctions. Photoelectron spectroscopy (UPS, IPES and XPS) results for the molecule-Si band alignment at equilibrium show the Fermi level to LUMO energy difference to be much smaller than the corresponding Fermi level to HOMO one. This result supports the conclusion we reach, based on negative differential resistance in an analogous semiconductor-inorganic insulator/metal junction, that for both p ++ -and n ++ -type junctions the energy difference between the Fermi level and LUMO, i.e., electron tunneling, controls charge transport. The Fermi level-LUMO energy difference, experimentally determined by IPES, agrees with the non-resonant tunneling barrier height deduced from the exponential length-attenuation of the current.

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Section: Resultssupporting

confidence: 66%

Charge transport across metal/molecular (alkyl) monolayer-Si junctions is dominated by the LUMO level

Yaffe

Scheres

et al. 2012

Phys. Rev. B

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“…On Mo(110), C K-edge NEXAFS (near-edge X-ray absorption fine structure) indicates the molecular plane is tilted from the surface normal by 23º [19], while on Ni(100) S K-edge NEXAFS indicates that the S-C bond (which lies in the phenyl plane in the free molecule) is 'nearly normal to the surface' [18]. On the Au surfaces, on the other hand, a lying-down geometry appears to be favored even at the highest coverage achievable by UHV dosing: on Au(110) this conclusion is inferred only from the maximum achievable coverage, and estimates of the van der Waals radius of the molecule [16], but on Au(111) this conclusion comes from electronic and vibrational spectroscopy [15]. On Cu(110), it appears that the benzenethiolate may lie flat at low coverage but stands up at high coverages [12].…”

Section: Introductionmentioning

confidence: 99%

“…Ultra-high vacuum surface-science studies of the interaction of benzenethiol with metal surfaces seem to be limited mainly to Cu ((111) [9,10], (110) [11,12], (410) [13], (100) [14]) and Au ((111) [15], (110) [16 ]) noble metal surfaces, although a number of investigations on the more reactive transition metal surfaces, including Ni(111) [17], 3 Ni(100) [18], Mo(110) [19,20], Rh(111) [21], are available in the literature, for which the motivation is more related to desulfurization catalysis. On all of these surfaces there is clear evidence for deprotonation of the thiol to produce the thiolate; on the transition metal surfaces this typically occurs even by adsorption at ~100 K, with further decomposition or reaction occurring below room temperature, but on the noble metal surfaces the thiolate appears to be stable at room temperature.…”

Section: Introductionmentioning

confidence: 99%

The local adsorption geometry of benzenethiolate on Cu(100)

et al. 2008

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The local adsorption geometry of benzenethiolate in the ordered c(2x6) phase on Cu (100) has been investigated by a combination of S K-edge near-edge X-ray absorption fine structure (NEXAFS), normal incidence X-ray standing waves (NIXSW) and S 1s scanned-energy mode photoelectron diffraction (PhD). NEXAFS and PhD show that the molecular plane is tilted from the surface normal by 2015°, while NIXSW clearly identifies the S headgroup as occupying the four-fold coordinated hollow sites. PhD shows the S atoms lies 1.340.04 Å above the outermost Cu atomic layer, leading to a Cu-S bondlength of 2.250.02 Å. The combination of the PhD and NIXSW results shows the Cu surface layer has an outward relaxation of 0.150.06 Å. Possible origins for this large adsorbate-induced relaxation are discussed.

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“…Within the context of the STM, this technique is denoted as inelastic electron tunneling spectroscopy (STM-IETS) and is extensively employed to characterize the molecule's vibrational spectra. [9][10][11][12][13][14][15] From the theoretical side, a wealth of formalisms dealing with the inelastic transport have been developed in parallel to these delicate experiments. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] The earliest models for IETS employed a multiple scattering formalism (multichannels) with simplified semiempirical Hamiltonians 16 or a Tersoff-Hamman-(TH-) type approach.…”

Section: Introductionmentioning

confidence: 99%

Lowest order in inelastic tunneling approximation: Efficient scheme for simulation of inelastic electron tunneling data

2013

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We have developed an efficient and accurate formalism which allows the simulation at the ab initio level of inelastic electron tunneling spectroscopy data under a scanning tunneling microscope setup. It exploits fully the tunneling regime by carrying out the structural optimization and vibrational mode calculations for surface and tip independently. The most relevant interactions in the inelastic current are identified as the inelastic tunneling terms, which are taken into account up to lowest order, while all other inelastic contributions are neglected. As long as the system is under tunneling regime conditions and there is no physisorbed molecule on the surface or tip apex, this lowest order in inelastic tunneling (LOIT) approach reduces drastically the computational cost compared to related approaches while maintaining a good accuracy. Adopting the wide-band limit for both tip and surface further reduces calculation times significantly, and is shown to give similar results to when the full energy dependence of the Green's functions is taken into account. The LOIT is applied to the Cu(111) + CO system probed by a clean and a CO contaminated tip to find good agreement with previous works. Different parameters involved in the calculations such as basis sets, k sampling, tip-sample distance, or temperature, among others, are discussed in detail.

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Benzenethiol adsorption on Au(111) studied by synchrotron ARUPS, HREELS and XPS

Cited by 116 publications

References 44 publications

Charge transport across metal/molecular (alkyl) monolayer-Si junctions is dominated by the LUMO level

Charge transport across metal/molecular (alkyl) monolayer-Si junctions is dominated by the LUMO level

The local adsorption geometry of benzenethiolate on Cu(100)

Lowest order in inelastic tunneling approximation: Efficient scheme for simulation of inelastic electron tunneling data

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