Influence of Magnetic Field on Evaporation of Water and Ionic Solutions

The evaporation of water in half-filled beakers and sessile droplets is studied in the presence and absence of a static magnetic field produced by permanent magnets. The main difference between the two is that water in beakers in the steady state evaporates into a reservoir of air loaded with its own its own fresh vapour. The ratio of otho to para nuclear isomers, which behave effectively as independent gasses is 39:61, whereas water in droplets evaporates into open ambient air where the ratio of the triplet to singlet is 3:1. The isomeric ratio of fresh vapour is deduced from the change of evaporation rate in a magnetic field, whose principal effect is to equalize the isomer populations due to dephasing of nuclear Larmor precession in a magnetic field gradient. The field increases the evaporation rate of 2M or 4M LiCl, NaCl and KCl are comparable to that in water. 1M NaCl is anomaloua. The field decreases the evaporation rate and the isomeric ratio is 60:40. A similar field effect found for a 1 M NaCl sessile droplet confined in a 1mL cuvette.