Figure 1: (Non) TIR SFG-VS mechanisms and applications in cellulose non-uniformity characterization.
From: Discovery of Cellulose Surface Layer Conformation by Nonlinear Vibrational Spectroscopy
(a) TIR SFG-VS design on cellulose surface observation and (b) non- TIR SFG-VS on cellulose bulk characterization. IR and VIS refers to infrared and visible 532 nm beams, respectively. (c) TIR geometry can only measure the outer layer of the material limited by the penetration depth up to about λ/2; (d) Simulation of surface SFG intensity under different visible and IR incident angles from the non-TIR to TIR conditions (details in supplementary information). It is clear that if the signal is from the same source, then the TIR signal can be two orders of magnitude stronger than the non-TIR condition.
