Oct 19, 2010
Nanoscale SERS becomes uniform at the macroscale
Surface enhanced Raman scattering (SERS) on nanoscale metallic structures allows for ultrasensitive label-free molecular spectroscopy. However, for more than 40 years, it has always been a lingering problem that this nanoscale physical phenomenon is neither repeatable nor uniform at the macroscale due to limitations in nanofabrication and optical characterization.
Now, a very large scale SERS substrate has been made on the entire surface of a 6 inch diameter silica wafer surface based on ultraviolet laser interference lithography. In addition, the team, which includes researchers from the University of Illinois at Urbana-Champaign and Lawrence Livermore National Laboratory, has demonstrated a very rigorous optical characterization of the nanoscale SERS spectra of a self-assembled monolayer at many spots over the macroscale surface.
Extremely high spectral uniformity, repeatability and statistical significance in Raman signal enhancement factors over the macroscale surface are shown in the group's characterization study. The report also provides the most detailed descriptions to date concerning the optical characterization procedure of a SERS substrate device.
Scanning electron microscopy images of the silver-coated tapered silica nanopillar arrays reveal high uniformity over a very large area across the entire 6 inch wafer surface. The SERS spectral measurements from multiple randomly distributed spots indicate a uniform SERS enhancement factor all over the wafer surface as the Raman peak intensities in all shown spectra are consistent and of the same order of magnitude.
The work shows promising engineering solutions to remove the barrier and pave the road for the high-performance industrial application of SERS molecular detection.
Full details can be found in the journal Nanotechnology.
About the author
The research was conducted by a collaborative team led by Prof. Logan Liu from the department of electrical and computer engineering at the University of Illinois at Urbana-Champaign (UIUC) and Dr Tiziana Bond at Lawrence Livermore National Laboratory (LLNL). Dr Tiziana Bond and her colleagues at LLNL have used the unique large-scale laser interference lithography to make many highly uniform nanostructured arrays even at metre scales. Prof. Logan Liu is director of the Nanobionics research group and also a faculty member in the Micro and Nanotechnology Laboratory at UIUC. His graduate students Manas Gartia and Zhida Xu performed the thorough optical characterization and analysed the data.