Surface enhanced Raman scattering on gold nanowire arrays: Evidence of strong multipolar surface plasmon resonance enhancement

The SERS efficiency of gold nanowires arrays elaborated by electron beam lithography and lift-off technique efficiency is investigated by depositing a molecular probe (BPE) trans-1,2-bis(4-pyridyl)ethylen on the arrays and using an excitation wavelength of 632.8 nm. The observation of the dependence of the Raman enhancement versus the nanowire length is clearly demonstrated and remarkably a maximum enhancement is observed. For such arrays, we also show clearly that odd multipolar localised surface plasmon modes (up to seventh-order) exhibits a stronger efficiency than the first dipolar order in SERS process.