Scanning Tunneling Spectroscopy (Sts)

Hipps, K. W.

doi:10.1007/0-387-37590-2_7

Cited by 45 publications

(76 citation statements)

References 104 publications

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“…On the basis of UPS, the electrochemical measurements, and assuming that the work function of the surface is 5 eV, one would expect the orbitalmediated tunneling spectrum (OMTS) to contain a band near -3.0 V (HOMO resonance) and + 1.5 V (LUMO resonance). 37 Since the data range shown in Figure 6 extends from -2 to +2 V, it is not surprising that the only band seen (in Figure 6) is due to the LUMO based electron affinity band and is located at +1.4 V bias (about 3.6 eV below the vacuum level). Correspondingly, the diimide-HOPG surface shows very strong rectification as shown in Figure 7.…”

Section: Electronic Structures I-v and Omtsmentioning

confidence: 93%

Scanning Tunneling Microscopy and Orbital-Mediated Tunneling Spectroscopy of N,N′-Dioctyl-1,8:4,5-naphthalenediimide Adsorbed on Highly Ordered Pyrolytic Graphite from Various Solvents and in Different Environments

et al. 2008

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Scanning tunneling microscopy (STM) and orbital-mediated tunneling spectroscopy (OMTS) are reported for N, N′-dioctyl-1,8:4,5-naphthalenediimide (diimide) adsorbed on highly ordered pyrolytic graphite (HOPG). The diimide forms well ordered monolayers either at the interface between HOPG and several phenylalkanes, or at the HOPG-air or HOPG-vacuum interface when adsorbed from toluene. Planar adsorption of the diimide ring on HOPG is observed. Hydrogen bonding, O and N interaction with HOPG, and π-π interactions appear to be the primary drivers for determining the monolayer structure which is stable and independent of the adsorption method. This is an unusual example since most alkane-substituted systems studied to date rely on alkane chain interactions (with HOPG and interdigitation) to drive the adsorbate structure on graphite. The observed unit cell has a ) 2.0 ( 0.2 nm, b ) 1.95 ( 0.2 nm, R ) 67 ( 2°. The STM imaging is highly bias dependent and appears to be controlled (in the (2 V bias region) by an unoccupied orbital. Orbitalmediated tunneling spectra reveal a single strong electron affinity band near 3.5 eV below the vacuum level.

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Section: Electronic Structures I-v and Omtsmentioning

confidence: 93%

Scanning Tunneling Microscopy and Orbital-Mediated Tunneling Spectroscopy of N,N′-Dioctyl-1,8:4,5-naphthalenediimide Adsorbed on Highly Ordered Pyrolytic Graphite from Various Solvents and in Different Environments

et al. 2008

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“…This approach has been extended to a number of molecular systems,2 including DNA 3, 4. Potential distributions in UHV are reproducible enough for precise molecular identification in many cases.…”

Section: Introductionmentioning

confidence: 99%

Recognition tunneling

Lindsay

Sankey

et al. 2010

Nanotechnology

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Single molecules in a tunnel junction can now be interrogated reliably using chemically-functionalized electrodes. Monitoring stochastic bonding fluctuations between a ligand bound to one electrode and its target bound to a second electrode (“tethered molecule-pair” configuration) gives insight into the nature of the intermolecular bonding at a single molecule-pair level, and defines the requirements for reproducible tunneling data. Simulations show that there is an instability in the tunnel gap at large currents, and this results in a multiplicity of contacts with a corresponding spread in the measured currents. At small currents (i.e. large gaps) the gap is stable, and functionalizing a pair of electrodes with recognition reagents (the “free analyte” configuration) can generate a distinct tunneling signal when an analyte molecule is trapped in the gap. This opens up a new interface between chemistry and electronics with immediate implications for rapid sequencing of single DNA molecules.

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“…The electrochemical oxidation potentials corresponded to the ionization energy of the metal complex of the metal-centered HOMO. 7,[45][46][47] Also, the electrochemical reduction potentials corresponded to the electron affinity energy of the metal complex, which belonged to the ligand-centered LUMO. 7,[45][46][47] The energies of the groundstate HOMO were calculated using the redox potentials of the Fe 2+ /Fe 3+ redox couples (E 1/2 ¼ 1.15 (AE0.02) V SCE versus saturated calomel electrode (SCE)), Ru 2+ /Ru 3+ redox couples (E 1/2 ¼ 1.32 (AE0.02) V SCE ), and Co 2+ /Co 3+ redox couples (E 1/2 ¼ 0.35 (AE0.02) V SCE ).…”

Section: Central Metal-dependent Multiple Electroreduction Of Metal C...mentioning

confidence: 99%

“…7,[45][46][47] Also, the electrochemical reduction potentials corresponded to the electron affinity energy of the metal complex, which belonged to the ligand-centered LUMO. 7,[45][46][47] The energies of the groundstate HOMO were calculated using the redox potentials of the Fe 2+ /Fe 3+ redox couples (E 1/2 ¼ 1.15 (AE0.02) V SCE versus saturated calomel electrode (SCE)), Ru 2+ /Ru 3+ redox couples (E 1/2 ¼ 1.32 (AE0.02) V SCE ), and Co 2+ /Co 3+ redox couples (E 1/2 ¼ 0.35 (AE0.02) V SCE ). The energies of the ground-state LUMOs were estimated using the potentials of tpy/tpy À /tpy 2À /tpy 3À redox couples, which were varied according to the central metal atoms.…”

Section: Central Metal-dependent Multiple Electroreduction Of Metal C...mentioning

confidence: 99%

Multilevel conductance switching for a monolayer of redox-active metal complexes through various metallic contacts

et al. 2012

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Redox-active metal complexes (e.g., Fe II , Ru II , and Co II biphenylterpyridine) exhibiting multiple electroreduction behaviors show multilevel conductance switching through various metallic contacts, including Au, Pt/Ir, and reduced graphene oxide (rGO), in solid-state molecular junctions (e.g., a metal-molecule-metal junction). At Pt/Ir and Au contacts in the scanning tunneling microscopy (STM)-based junctions or Au/rGO film contacts in monolayer-based devices, current-voltage (I/V) characteristics have different energy distributions depending on the level of injection into the three electron affinity levels of the redox-active metal complexes. These metal complexes can be negatively charged when the energy levels between the Fermi levels of the metal contacts and the molecular reduction states are aligned, which strongly depends upon the molecular conductance states of conjugated ligands coordinated to central metal atoms. Multiple reduction states of redox-active metal complexes measured with solution-phase electrochemistry correspond to the multiple electron affinity levels of the solid-state molecular junctions, which suggests the possibility of multilevel molecular memory components.

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Scanning Tunneling Spectroscopy (Sts)

Cited by 45 publications

References 104 publications

Scanning Tunneling Microscopy and Orbital-Mediated Tunneling Spectroscopy of N,N′-Dioctyl-1,8:4,5-naphthalenediimide Adsorbed on Highly Ordered Pyrolytic Graphite from Various Solvents and in Different Environments

Scanning Tunneling Microscopy and Orbital-Mediated Tunneling Spectroscopy of N,N′-Dioctyl-1,8:4,5-naphthalenediimide Adsorbed on Highly Ordered Pyrolytic Graphite from Various Solvents and in Different Environments

Recognition tunneling

Multilevel conductance switching for a monolayer of redox-active metal complexes through various metallic contacts

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