Direct and quantitative broadband absorptance spectroscopy on small objects using Fourier transform infrared spectrometer and bilayer cantilever probes

A measurement platform is introduced that combines a bilayer cantilever probe with a Fourier transform infrared spectrometer to measure absolute spectral absorptance between wavelengths of 3 μm and 18 μm directly and quantitatively. The enhanced sensitivity provided by the cantilever probe enables the quantitative characterization of micro- and nanometer-sized samples. Validation of the technique is carried out by measuring the absorptance spectrum of a doped silicon thin film with a backside aluminum layer and found to agree well with the theoretical predictions. The presented technique is especially attractive for samples such as individual nanowires or nanoparticles, isolated molecules, powders, and photonic structures.United States. Dept. of Energy (Office of Basic Energy Sciences, Grant No. DE-FG02- 02ER45977)United States. Dept. of Defense (MURI via UIUC FA9550-08-1-0407)National Research Fund Luxembourg (Grant No. 893874