Fig. 1.

Temperature dependence of water spectrum. Extinction coefficient of pure water spectra (${\mathrm{H}}_2\mathrm{O}$) simulated as a function of temperature (range 30°C to 40°C) over NIR: (a) 600 to 980 nm and (b) 720–880 nm.^7,8 Pronounced water absorption peaks appear in the NIR around 740, 840, and 970 nm (marked by red vertical lines). Units are given in temperature (°C) with increasing extinction indicating increasing temperature (color coded from blue to red).