Revealing the molecular structure of single-molecule junctions in different conductance states by fishing-mode tip-enhanced Raman spectroscopy

The conductance of single-molecule junctions may be governed by the structure of the molecule in the gap or by the way it bonds with the leads, and the information contained in a Raman spectrum is ideal for examining both. Here we demonstrate that molecule-to-surface bonding may be characterized during electron transport by 'fishing-mode' tip-enhanced Raman spectroscopy (FM-TERS). This technique allows mutually verifiable single-molecule conductance and Raman signals with single-molecule contributions to be acquired simultaneously at room temperature. Density functional theory calculations reveal that the most significant spectral change seen for a gold-4,4′-bipyridine-gold junction results from the deformation of the pyridine ring in contact with the drain electrode at high voltage, and these calculations suggest that a stronger bonding interaction between the molecule and the drain may account for the nonlinear dependence of conductance on bias voltage. FM-TERS will lead to a better understanding of electron-transport processes in molecular junctions.

[1]  Parr,et al.  Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. , 1988, Physical review. B, Condensed matter.

[2]  W. R. Wadt,et al.  Ab initio effective core potentials for molecular calculations. Potentials for K to Au including the outermost core orbitals , 1985 .

[3]  E. Leary,et al.  Impact of Junction Formation Method and Surface Roughness on Single Molecule Conductance , 2009 .

[4]  Ho,et al.  Single-molecule vibrational spectroscopy and microscopy , 1998, Science.

[5]  B. Mao,et al.  Single Molecule Conductance of Dipyridines with Conjugated Ethene and Nonconjugated Ethane Bridging Group , 2008 .

[6]  W. R. Wadt,et al.  Ab initio effective core potentials for molecular calculations , 1984 .

[7]  Mark A. Reed,et al.  Inelastic Electron Tunneling Spectroscopy of an Alkanedithiol Self-Assembled Monolayer , 2004 .

[8]  Amir Yacoby,et al.  Measurement of the conductance of single conjugated molecules , 2005, Nature.

[9]  Katrin F. Domke,et al.  Enhanced Raman spectroscopy: Single molecules or carbon? , 2007 .

[10]  R. McCreery.  Analytical challenges in molecular electronics. , 2006, Analytical chemistry.

[11]  De‐Yin Wu,et al.  Tip-enhanced Raman spectroscopy for investigating adsorbed nonresonant molecules on single-crystal surfaces: tip regeneration, probe molecule, and enhancement effect , 2009 .

[12]  Yun Hee Jang,et al.  Observation of molecular orbital gating , 2009, Nature.

[13]  R. Dasari,et al.  Single Molecule Detection Using Surface-Enhanced Raman Scattering (SERS) , 1997 .

[14]  S. Louie,et al.  Mechanically controlled binary conductance switching of a single-molecule junction. , 2009, Nature nanotechnology.

[15]  B. Pettinger,et al.  Tip-enhanced Raman spectroscopy and microscopy on single dye molecules with 15 nm resolution. , 2008, Physical review letters.

[16]  A. Becke.  Density-functional thermochemistry. III. The role of exact exchange , 1993 .

[17]  Yuyuan Tian,et al.  Measurement of Single-Molecule Resistance by Repeated Formation of Molecular Junctions , 2003, Science.

[18]  Mark A. Ratner,et al.  Nuclear Coupling and Polarization in Molecular Transport Junctions: Beyond Tunneling to Function , 2008, Science.

[19]  C. Lambert,et al.  Precision control of single-molecule electrical junctions , 2006, Nature materials.

[20]  J. Xia,et al.  Electron transport in single molecules measured by a distance-modulation assisted break junction method. , 2008, Nano letters.

[21]  T. Mayer,et al.  Crossed-nanowire molecular junctions: a new multispectroscopy platform for conduction--structure correlations. , 2010, Nano letters.

[22]  M. Ratner,et al.  Chemical fabrication of heterometallic nanogaps for molecular transport junctions. , 2009, Nano letters.

[23]  James M Tour,et al.  Vibrational and electronic heating in nanoscale junctions. , 2011, Nature nanotechnology.

[24]  Volker Deckert,et al.  Tip-enhanced Raman scattering. , 2008, Chemical Society reviews.

[25]  Stanislaus S. Wong,et al.  Optical nanocrystallography with tip-enhanced phonon Raman spectroscopy. , 2009, Nature nanotechnology.

[26]  H. Abruña,et al.  Electron transfer through molecules and assemblies at electrode surfaces. , 2008, Chemical reviews.

[27]  Z. Ioffe,et al.  Detection of heating in current-carrying molecular junctions by Raman scattering. , 2008, Nature nanotechnology.

[28]  Zhong-Qun Tian,et al.  Tip-enhanced Raman spectroscopy for investigating adsorbed species on a single-crystal surface using electrochemically prepared Au tips , 2007 .

[29]  Mototsugu Suzuki,et al.  Adsorption characteristics of 4,4′-bipyridine molecules on gold nanosphere films studied by surface-enhanced Raman scattering , 2006 .

[30]  Andreas Arnold,et al.  Charge transport in single Au / alkanedithiol / Au junctions: coordination geometries and conformational degrees of freedom. , 2008, Journal of the American Chemical Society.

[31]  C. H. Patterson,et al.  Vibronic contributions to charge transport across molecular junctions , 2004 .

[32]  Steven R. Emory,et al.  Probing Single Molecules and Single Nanoparticles by Surface-Enhanced Raman Scattering , 1997, Science.

[33]  N. J. Tao,et al.  Electron transport in molecular junctions , 2006, Nature nanotechnology.

[34]  S. Kawata,et al.  Pressure-assisted tip-enhanced Raman imaging at a resolution of a few nanometres , 2009 .

[35]  John K. Tomfohr,et al.  Reproducible Measurement of Single-Molecule Conductivity , 2001, Science.

[36]  James M Tour,et al.  Simultaneous measurements of electronic conduction and Raman response in molecular junctions. , 2008, Nano letters.

[37]  M. Reed,et al.  Conductance of a Molecular Junction , 1997 .

[38]  G. Schatz,et al.  Surface-enhanced raman scattering of pyrazine at the junction between two Ag20 nanoclusters. , 2006, Nano letters.

[39]  Lukas Novotny,et al.  High-resolution near-field Raman microscopy of single-walled carbon nanotubes. , 2003, Physical review letters.

[40]  W. R. Wadt,et al.  Ab initio effective core potentials for molecular calculations. Potentials for main group elements Na to Bi , 1985 .

[41]  Bo Liu,et al.  Study of molecular junctions with a combined surface-enhanced Raman and mechanically controllable break junction method. , 2006, Journal of the American Chemical Society.

[42]  Jian-Feng Li,et al.  Expanding generality of surface-enhanced Raman spectroscopy with borrowing SERS activity strategy. , 2007, Chemical communications.