Abstract
Lithographic and nonlithographic two-dimensional (2D) substrates for surface-enhanced Raman spectroscopy (SERS) have gained enormous popularity as analytical platforms for detection and identification of various analytes. However, their near- and far-field properties in most cases remain poorly understood. We have previously developed a metal nanopillar film over nanospheres (FON) platform exhibiting Raman enhancement factors of ∼107. These substrates have a reproducible and predictable localized surface plasmon resonance throughout the entire visible region and much of the near-IR region of the electromagnetic spectrum. Extending upon these results, we have utilized wavelength-scan surface-enhanced Raman excitation spectroscopy to unravel the relationship between near- and far-field properties of FON surface-enhanced Raman spectroscopy substrates. We examined by scanning electron microscopy FONs fabricated by either stationary (ST-FONs) or spun (SP-FONs) metal deposition to examine the interrelationships of nanoscale structure and near- and far-fied properties. We demonstrate that the line width and spectral position of the far-field and near-field resonances of ST- and SP-FONs directly depend on the nanofeature distribution at the metallic surface. In particular, we show that the actual nanofeature morphology and distribution directly impact the spectral alignment of the far-field and near-field resonances.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 14737-14744 |
| Number of pages | 8 |
| Journal | Journal of Physical Chemistry C |
| Volume | 121 |
| Issue number | 27 |
| DOIs | |
| State | Published - Jul 13 2017 |
Funding
This work made use of the EPIC facility of Northwestern University's NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (National Science Foundation (NSF) Grant ECCS-1542205), the MRSEC program (NSF Grant DMR-1121262) at the Materials Research Center, the International Institute for Nanotechnology (IIN), the Keck Foundation, and the State of Illinois, through the IIN. This work was also supported by the NSF CaSTL Center (NSF Grant CHE-1414466) and by AFOSR MURI Grant FA9550- 14-1-0003. N.L. acknowledges financial support from the Department of Physics and Astronomy and from the College of Science of The University of Texas at San Antonio. Computing resources were provided by the Quest highperformance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology (NUIT). This material is also based on research sponsored by the Air Force Research Laboratory under Agreement FA8650-15-2-5518. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Air Force Research Laboratory or the U.S. Government. Finally, this work was supported by the Assistant Secretary of Defense for Health Affairs, through the Peer Reviewed Medical Research Program under Award No. W81XWH-16-1-0375. The opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the Department of Defense.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- General Energy
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films