Parahydrogen

Some articles on parahydrogen:

Spin Isomers Of Hydrogen - Thermal Properties
... Conversely, parahydrogen with an antisymmetric nuclear spin function, can only have rotational wavefunctions that are symmetric with respect to permutation of the two protons ... here are molar rotational energies and heat capacities for ortho- and parahydrogen, and the "normal" ortho/para (31) and equilibrium mixtures Molar Rotational Energies ... Notably, the boiling points of parahydrogen and normal (31) hydrogen are nearly equal for parahydrogen ∆Hvap = 898 J/mol at Tb = 20.277 K ...
Theory of Heat Capacity - Energy Storage Mode "freeze-out" Temperatures
... in the degree of freedom available when parahydrogen (in which spins are anti-aligned) absorbs energy, and is converted to the higher energy ortho form ... large enough to "freeze out" at this low temperature), and thus the parahydrogen form predominates ... transition is sufficient to release enough heat, as orthohydrogen converts to the lower-energy parahydrogen, to boil the hydrogen liquid to gas again, if this evolved heat is not removed with a catalyst after ...
Spin Isomers Of Hydrogen - Use in NMR
... When an excess of parahydrogen is used during hydrogenation reactions (instead of the normal mixture of orthohydrogen to parahydrogen of 31), the resultant product ... This effect is called PHIP ("Parahydrogen Induced Polarisation") or PASADENA ("Parahydrogen and Synthesis allow dramatically enhanced nuclear alignment" – named this way as the ...