2DCOS and PCMW2D analyses of FT-IR/ATR and FT-NIR spectra monitoring the deuterium/hydrogen exchange in liquid D2O

• Detailed study of the isotope exchange reaction of liquid D2O with ambient H2O vapor.
• Derivation of a reaction sequence scenario of the involved isotopic species.
• Differentiation of strongly and weakly deuterium/hydrogen-bonded HDO.
• Proof of concept of the 2DCOS and PCMW2D techniques.

The derivation of sequence-related information is one of the most disputed and criticized issues of 2DCOS analysis. In order to prove the potential of its application as well as the rationality of the conclusions derived thereof a very simple isotope exchange reaction has been chosen as the experimental basis. Thus, a droplet of D2O was exposed to the atmosphere and the D/H-exchange reaction with the surrounding water vapor was monitored by FT-IR/ATR and FT-NIR transmission spectroscopy as a function of time. In the latter case the experiments were additionally performed at variable temperature. Two-dimensional correlation spectroscopic (2DCOS) and perturbation–correlation moving-window two-dimensional (PCMW2D) analyses were applied to the time-resolved spectra in order to extract detailed information regarding the time-dependent concentration changes of the involved liquid isotopic D2O, HDO and H2O species.