Fig. 4: BSTP imaging of polyurethane beads.
From: Bond-selective transient phase imaging via sensing of the infrared photothermal effect
a Quantitative phase image of PU beads. b,c BSTP imaging of PU beads at an absorption peak of 2980 cm−1 and an off-resonance peak at 2700 cm−1, respectively. d BSTP spectral profile of PU beads (top) and the measured standard FTIR spectrum (bottom). e BSTP (blue squares) and raw phase (black line) profiles of the smaller PU bead across the dashed line marked in b.
