Nuclear spin conversion in ${\mathrm{H}}_2\mathrm{O}$ revisited

Conversion of water nuclear-spin isomers by the quantum relaxation phenomenon is revisited and the high stability of water isomers is predicted. As an example, the isomer lifetime is found equal to 18 hours at room temperature and the water vapor pressure equal to $\simeq 5$ torr. Our calculations correct the prediction of rather short lifetime of water spin isomers, $\approx 1$ s, made by Cacciani et al. [Phys. Rev. A 85, 012521 (2012)].

Figure 1

Structure of ${\mathrm{H}}_2$O molecule and the “b-frame” system of molecular coordinates. The quantization $z$ axis is directed along the principle b axis of inertia moment towards the oxygen nucleus. The $x$ axis is directed towards the ${\mathrm{H}}_1$ nucleus. Directions of the principle axes of inertia moments are indicated in ascending order of corresponding moments of inertia: $I_a<I_b<I_c$.

Figure 2

Energies of collapsing para states calculated in this work and measured energies of these states as presented in Ref. [22].

Figure 3

Energy difference between ortho-para level gaps of collapsing states $|J^{\prime },{\mathcal{K}}^{\prime }=0,p^{\prime }=0.5(1-{(-1)}^{J^{\prime }})\rangle -|J=J^{\prime },\mathcal{K}=1,p=p^{\prime }\rangle$ calculated in the present work and experimental data from Ref. [22].