Al nanoantennas for plasmon-enhanced infrared spectroscopy

The high cost associated with the traditional plasmonic materials and the complex nanofabrication has hindered their practical applications and therefore alternative plasmonic materials and nanofabrication techniques are needed. Here, I combined cost-effective colloidal lithography and earth-abundant element, i.e. Al, to fabricate Al optical nanoantennas including Al nanotriangles and Al metamaterial perfect absorbers. I demonstrate surface functionalization of the nanoantennas using phosphonic acid and subsequent detection of the C=O vibration mode via surface-enhanced infrared absorption spectroscopy. In addition, the detection of a physically adsorbed thin polymer layer on the Al nanoantennas is demonstrated. Surface functionalization with phosphonic acid provides various functional groups to the Al surfaces opening up great opportunities for Al-based plasmonic nanostructures for biochemical sensing applications.