The Grassian group is involved in several research areas including surface chemistry of environmental interfaces, heterogeneous atmospheric chemistry, climate impact of atmospheric aerosols, and environmental and health aspects of nanoscience and nanotechnology.
Atomic Force Microscopy-Infrared Spectroscopy (AFM-IR)
AFM-IR combines infrared (IR) spectroscopy and atomic force microscopy (AFM) to enable measurements of materials on the nanoscale level. Traditional IR spectroscopy, a powerful technique used to identify function groups and to measure the frequency of vibrational modes within molecular species has its limitations because of optical diffraction limits. The typical spatial resolution of IR spectra using conventional absorption instruments has been several microns to tens of microns. AFM on the other hand, can analyze samples down to the nanoscale level however, cannot provide chemical information of the material of interest.
AFM-IR uses the resonant response of the AFM tip to IR light pulses incident on the sample in order to measure the IR spectrum. The AFM not only makes possible spectral analysis of submicrometer samples but also measures the thermal and mechanical properties of a sample.
The Grassian group makes use of AFM-IR in looking at the morphology, size, as well as chemical information of substrate-deposited aerosol particles down to less than 100 nm. The technique is also be used to study other environmental samples including indoor surfaces.