Localized IR spectroscopy of hemoglobin.

IR absorption spectroscopy of hemoglobin was performed using an infrared (IR) optical parametric oscillator laser and a commercial atomic force microscope (AFM) in a novel experimental arrangement based on the use of a bottom-up excitation alignment. This experimental approach enables detection of protein samples with resolution much higher than that of standard IR spectroscopy. Presented here are AFM-based IR absorption spectra of micron-sized hemoglobin features.