Increase in the Relative Content of ortho-Н2О Molecules in Vapor above Boiling Water

The spin selectivity of the processes occurring in vapor above the surface of boiling water has been experimentally demonstrated. This selectivity leads to a significant increase in the fraction of ortho-H₂O molecules in vapor. An increase in the relative content of ortho/para-isomers of water from the equilibrium value of 3 : 1 (determined by quantum statistics) to 5 : 1 was observed. The content of H₂O spin isomers in vapor above the water surface was analyzed using a tunable diode laser. Spectral analysis of the ortho- and para-H₂O content was performed using the absorption lines of these molecules belonging to the vibrational–rotational band 101-000 and having transition frequencies of 7355.557 and 7354.599 cm^–1, respectively. When water is heated from room temperature (20°C) to the second boiling phase (~80°C), a ratio of ortho- and para-spin isomers of ~3 : 1 was observed, which is typical of normal conditions. During the second and third boiling phases (80–90°C), the ortho/para ratio increases to 5:1. A possible mechanism for increasing the fraction of ortho-H₂O in the vapor formed during boiling may be associated with the depletion of the equilibrium mixture in the para-H₂O isomer, due to its higher activity in condensation and formation of water microdrops, dimers, and trimers.