Fig. 1.

Absorbance (a) and calibration plot (b) for normal water dissolved in deuterated water ${\mathrm{D}}_2\mathrm{O}$. (b), empty circles: slope at 1200 nm, molar absortivity ${\epsilon }_{1200}{=0.087\mathrm{M}}^{-1}{\mathrm{cm}}^{-1}$, $R_2=0.999$; solid squares: ${\epsilon }_{1400}=1400\mathrm{nm}$, slope at 1400 nm, molar absorptivity ${\epsilon }_{1400}{=1.044\mathrm{M}}^{-1}{\mathrm{cm}}^{-1}$, $R_2=1$. (c) Molar absorptivity plot of ${\mathrm{H}}_2\mathrm{O}$ and ${\mathrm{D}}_2\mathrm{O}$. References: for ${\mathrm{D}}_2\mathrm{O}$ spectrum—air; for ${\mathrm{H}}_2\mathrm{O}$ spectrum—${\mathrm{D}}_2\mathrm{O}$. The molar absorptivity spectra of ${\mathrm{D}}_2\mathrm{O}$ were recorded using one point of concentration 55.3 M (${\mathrm{D}}_2\mathrm{O}$) using air as a reference.