Pressure-enhanced ortho-para conversion in solid hydrogen up to 58 GPa

We measured the ortho-para conversion rate in solid hydrogen by using Raman scattering in a diamond-anvil cell, extending previous measurements by a factor of 60 in pressure. We confirm previous experiments that suggested a decrease in the conversion rate above about 0.5 GPa. We observe a distinct minimum at 3 GPa followed by a drastic increase in the conversion rate to our maximum pressure of 58 GPa. This pressure enhancement of conversion is not predicted by previous theoretical treatments and must be due to a new conversion pathway.

Da Constituinte à Emenda Constitucional nº 58, de 2009 : o Poder Judiciário, o Congresso Nacional e a composição das Câmaras de Vereadores / Gilberto Guerzoni Filho.

Edição Especial : Senado Federal : 50 anos de Brasília.