Can ortho-para transitions for water be observed?

  title={Can ortho-para transitions for water be observed?},
  author={Andrea Miani and Jonathan Tennyson},
  journal={The Journal of chemical physics},
  volume={120 6},
The spectrum of water can be considered as the juxtaposition of the spectra of two molecules, with different total nuclear spin: ortho-H2O, and para-H2O. No transitions have ever been observed between the two different nuclear-spin isotopomers. The interconversion time is unknown and it is widely assumed that interconversion is forbidden without some other intervention. However, weak nuclear spin-rotation interaction occurs and can drive ortho to para transitions. Ab initio calculations show… CONTINUE READING