▎ 摘　　要

Noble metal dimers with sub-nanometer separation support strong electromagnetic field enhancement which has practical applications in surface enhanced Raman scattering (SERS), photodetection, and photocatalysis. Monolayer graphene is an excellent spacer material to practically realize uniform separation between the dimers. Here, directed microwave-assisted self-assembly of Au nanoparticle dimers is reported, separated by graphene monolayer over 1 cm(2) substrates. Detailed analytical models of Au particle formation kinetics explain the experimentally observed control of the density and selectivity of the dimer formation. SERS substrates with 7 x 10(6) cm(-2) of Au-Graphene-Au dimers are obtained which yield a 35-fold increase in the Raman spectral signal of graphene from a single dimer, and an enhancement factor in intensity per molecule of 10(7) allows ppb level detection of Rhodamine 6G. A system of such dimers can provide an efficient, reliable, and inexpensive solution for many nanophotonic applications that require ultrahigh field confinement, such as SERS and photodetection.