Supporting Information. Metallic Adhesion Layer Induced Plasmon Damping and Molecular Linker as a Non-Damping Alternative

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1 Supporting Information Metallic Adhesion Layer Induced Plasmon Damping and Molecular Linker as a Non-Damping Alternative Terefe G. Habteyes, Scott Dhuey, Erin Wood, Daniel Gargas, Stefano Cabrini, P. James Schuck, A. Paul Alivisatos and Stephen R. Leone E-beam resist coating and baking (polymethylmethacrylate, PMMA) E-beam lithography (1 kev, 5pA, 2 µc/cm 2 ) Development IPA:Water, 7:3 ratio, -5 o C E-beam evaporation of UV-ozone cleaning E-beam evaporation of / MPTMS vapor deposition E-beam evaporation of Figure S1 Schematics of the lithographic fabrication. See methods section for the description. IPA is isopropyl alcohol. Gold nanostructures are deposited directly on a glass surface (in some cases sonication is not applied to minimize the loss of structures), on an ~2 nm adhesion layer and on MPTMS functionalized glass surface. 1

2 ε ε ε 1 /ε Wavelength (nm) Figure S2 Dielectric function and field enhancement for titanium (black lines) and gold (blue lines). The real (dispersion) and the imaginary (dissipative) components of the dielectric function plotted as a function of wavelength of light. The field enhancement is proportional to the ratio of the real component to the imaginary component as plotted in. 2

3 Scattering intensity (arb. unit) Scattering intensity (arb. unit) Scattering cross-section (µm 2 ) Longitudinal mode (L) Transverse mode (T) Sum (L + T) Scattering cross-section (µm 2 ) (d) - Longitudinal mode (L) Transverse mode (T) Sum (L + T) Figure S3 Two Lorentzian functions are fitted to the scattering spectrum of nanorod, and - nanorod. and (d) the calculated spectra; the blue and green curves are obtained when the electric field of the excitation source is oriented along the long axis and short axis of the bar, respectively. The red curve is the sum of the two. 3

4 AFM images - on silicon wafer Height (nm) Line profile of the AFM images in - Silicon wafer Position (nm) SEM image Silicon wafer Figure S Surface morphology of film deposited on 2 nm adhesion layer. The film is formed by e-beam evaporation of and as described in the methods section. The atomic force microscope images and the corresponding line profiles clearly display the granular morphology of - film. The root mean square deviation of the - topography is 23 pm compared to 75 pm for that of the silicon wafer, where the film is deposited. The topographic feature of the silicon surface is attributed to the native oxide layer, in addition to noise. The grain structure of the - film can also be observed in the scanning electron microscope image.

5 (d) Figure S5 SEM image of lithographically fabricated gold structures. and the gold structures are supported directly on a glass substrate. and (d) the gold structures are supported on MPTMS pretreated glass substrate. It is evident that the MPTMS functionalization of the glass surface improves the adhesion of gold structures. The dashed circles in indicate the expected location of the missing structures that were washed away during the liftoff process. 5