Characterization of the Reaction Products of Laser-Ablated Lanthanide Metal Atoms with Molecular Hydrogen. Infrared Spectra of LnH, LnH<INF>2</INF>, LnH<INF>3</INF>, and LnH<INF>4</INF> Molecules in Solid Argon

Infrared spectra of representative LnH 1 - 4 lanthanide hydride molecules are observed in solid argon following reactions of the laser-ablated metal atoms with H 2 . The LnH 2 dihydride is the major product and a stable (H 2 )LnH 2 complex is observed for Ce and Pr. In addition, bands are also assigned to bridging hydrogen motions of several (LnH) 2 dimers. Supplementary density functional calculations of the lanthanide hydride reaction products reproduce general features of the spectra. Spectra of isolated molecular EuH 2 and solid stoichiometric EuH 2 reveal close correspondence, lending support to the molecular assignment and, by extrapolation, providing benchmark infrared frequencies for other lanthanide hydride solids based on their respective molecular vibrational modes.