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. 2020 Mar 9;7(10):1903644. doi: 10.1002/advs.201903644

Figure 2.

Figure 2

SRS imaging and quantification of polymer wave propagation. a) Hyperspectral SRS imaging of acrylamide/air interface after 3 min of uniform UV exposure. Scale bar, 50 µm. b) SRS spectra on the indicated locations in panel (a). The blue and orange dotted lines represent the SRS spectra of pure monomer (1) and polymer (3) for reference. c) Spectral SRS imaging of polymer formed by tightly focused UV laser. Scale bar, 30 µm. d) Two‐species 3D SRS imaging of both monomer and formed polymer structure. e) SRS recording of fast polymerization dynamics at every 4 s (Video S2, Supporting Information). Arrow indicates the polymer wave. Scale bar, 25 µm. f) Intensity profiles of monomer distribution across the initiation center (indicated by the dashed line in panel (e)). Purple curve indicates the boundary of UV laser on and off. g) Radius of propagating polymer waves with time at UV laser power of 1, 3, 5, and 9 mW. h) Linear dependence of propagation speeds of polymer waves with the UV laser power.