Effects of quantum tunneling in metal nanogap on surface-enhanced Raman scattering

The quantum tunneling effects between two silver plates are studied using the time dependent density functional theory. Our results show that the tunneling depends mainly on the separation and the initial local field of the interstice between plates. The smaller separation and larger local field, the easier the electrons tunnels through the interstice. Our numerical calculation shows that when the separation is smaller than 0.6 nm the quantum tunneling dramatically reduces the enhancing ability of interstice between nanoparticles.

[1]  Louis E. Brus,et al.  Ag Nanocrystal Junctions as the Site for Surface-Enhanced Raman Scattering of Single Rhodamine 6G Molecules , 2000 .

[2]  Baohua Gu,et al.  One-dimensional arrays of nanoshell dimers for single molecule spectroscopy via surface-enhanced Raman scattering. , 2006, The Journal of chemical physics.

[3]  George C. Schatz,et al.  A nanoscale optical biosensor: The long range distance dependence of the localized surface plasmon resonance of noble metal nanoparticles , 2004 .

[4]  M. Ishikawa,et al.  Local electric field and scattering cross section of Ag nanoparticles under surface plasmon resonance by finite difference time domain method , 2003 .

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

[6]  J. Simmons.  Electric Tunnel Effect between Dissimilar Electrodes Separated by a Thin Insulating Film , 1963 .

[7]  D. Mackowski,et al.  Scattering by two spheres in contact: comparisons between discrete-dipole approximation and modal analysis. , 1993, Applied optics.

[8]  In-Yong Park,et al.  High-harmonic generation by resonant plasmon field enhancement , 2008, Nature.

[9]  O. Martin,et al.  Resonant Optical Antennas , 2005, Science.

[10]  P. Johansson.  LIGHT EMISSION FROM A SCANNING TUNNELING MICROSCOPE : FULLY RETARDED CALCULATION , 1998, cond-mat/9809234.

[11]  Lukas Novotny,et al.  Optical frequency mixing at coupled gold nanoparticles. , 2007, Physical review letters.

[12]  J. Gillis,et al.  Matrix Iterative Analysis , 1961 .

[13]  Andrew G. Glen,et al.  APPL , 2001 .

[14]  F. K. Schulte.  A theory of thin metal films: electron density, potentials and work function , 1976 .

[15]  Thomas R Huser,et al.  Surface-enhanced Raman scattering from individual au nanoparticles and nanoparticle dimer substrates. , 2005, Nano letters.

[16]  Hongxing Xu,et al.  Electromagnetic energy flow near metal nanoparticles—II: Algorithms for the calculation of the light scattering of multi-spheres and photon energy transport via linear chains of Ag nanoparticles , 2007 .

[17]  Emil Prodan,et al.  Quantum description of the plasmon resonances of a nanoparticle dimer. , 2009, Nano letters.

[18]  Hongxing Xu,et al.  Spectroscopy of Single Hemoglobin Molecules by Surface Enhanced Raman Scattering , 1999 .

[19]  Xu,et al.  Electromagnetic contributions to single-molecule sensitivity in surface-enhanced raman scattering , 2000, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[20]  Yingzhou Huang,et al.  Polarization dependence of surface-enhanced Raman scattering in gold nanoparticle-nanowire systems. , 2008, Nano letters.

[21]  E. Gross,et al.  Density-Functional Theory for Time-Dependent Systems , 1984 .

[22]  Andreas Otto,et al.  What is observed in single molecule SERS, and why? , 2002 .