infrared absorption spectroscopy two-dimensional infrared spectroscopy 2D-IR two dimensional infrared spectroscopy 2010-07-24T11:15:46Z 2D IR CHMO:0002710 2DIR Hils two-dimensional infrared (2D-IR) spectroscopy Spectroscopy where the sample absorbs radiation from the infrared region (0.78–1000 \μm) over two frequency axes. Cross peaks in the spectrum encode the couplings and orientation between vibrations. two-dimensional IR spectroscopy