Quantitative rotational to librational transition in dense H2 and D2

Miriam Pena Alvarez, Veronika Afonina, Philip Dalladay-Simpson, Xiao-Di Liu, Ross T. Howie, Peter Cooke, Ioan B. Magdau, Graeme J. Ackland, Eugene Gregoryanz

Research output: Contribution to journalArticlepeer-review


Raman spectroscopy demonstrates that the rotational spectrum of solid hydrogen, and its isotope deuterium, undergo profound transformations upon compression while still remaining in phase I. We show that these changes are associated with a loss of quantum character in the rotational modes, ie. with increasing pressure, the angular momentum J gradually ceases to be a good quantum rotational number. Through isotopic comparisons of the rotational Raman contributions, we reveal that hydrogen and deuterium evolves from a quantum rotor to a harmonic oscillator. We find that the mechanics behind this transformation can be well described by a quantum mechanical single inhibited rotor, accurately reproducing the striking spectroscopic changes observed in phase I.
Original languageEnglish
Pages (from-to)6626-6631
Number of pages6
JournalThe Journal of Physical Chemistry Letters
Issue number16
Early online date16 Jul 2020
Publication statusPublished - 20 Aug 2020


Dive into the research topics of 'Quantitative rotational to librational transition in dense H2 and D2'. Together they form a unique fingerprint.

Cite this