title: Time-resolved study of crystallization in deeply cooled liquid parahydrogen.
abstract: We present real-time measurements of the crystallization process occurring in liquid para-hydrogen (para-H(2)) quenched to ≈0.65T(m) (T(m)=13.8   K is the melting point of bulk liquid para-H(2)). The combination of high spatial resolution Raman spectroscopy and liquid microjet generation allows, in situ, capturing structural changes with ∼10(-8)  s time resolution. Our results provide a crystal growth rate that rules out a thermally activated freezing process and reveal that the quenched melt freezes into a metastable polymorph, which undergoes a structural transition. The achieved temporal control offers new opportunities for exploring the elementary processes of nonequilibrium phase transformations in supercooled liquids.
authors.affiliation: Institut für Kernphysik, J W Goethe-Universität, Frankfurt am Main, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Kühnel
authors.forename: José M
authors.initials: JM
authors.lastname: Fernández
authors.forename: Guzmán
authors.initials: G
authors.lastname: Tejeda
authors.forename: Anton
authors.initials: A
authors.lastname: Kalinin
authors.forename: Salvador
authors.initials: S
authors.lastname: Montero
authors.forename: Robert E
authors.initials: RE
authors.lastname: Grisenti