Figure 1. Assignments of five-Gaussian components of OH stretching Raman bands and Raman spectra of OH stretching of various pure water and saline solutions.

(a), In deconvolution the five-Gaussian components with the center wavenumbers at 3018, 3223, 3393, 3506 and 3624 cm⁻¹ were adopted for all samples. The three components on the low frequency side are assigned to hydrogen-bonded water, while the remaining two high frequency side components are assigned to non-hydrogen-bonded water. The full width at half maximum (FWHM) of the individual component in the five-Gaussian fit was equal for all samples. These values are 234, 201, 176, 154 and 112 cm⁻¹ for bands at 3018, 3223, 3393, 3506 and 3624 cm⁻¹, respectively. Red capital letter D and blue capital letter A are noted as donor and acceptor of proton, respectively. (b), DI water for reference. (c), AuNT water under illumination with fluorescent lamps in preparation. (d), sAuNT water under illumination with green LED in preparation. (e), DI water with 0.9 wt% NaCl. (f), AuNT water with 0.9 wt% NaCl. (g), sAuNT water with 0.9 wt% NaCl.