The infrared absorption spectra (40-800 cm⁻¹) of the trifluorides
of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Tb, Ho, Er, Tm, and Yb isolated
in solid argon, krypton and nitrogen matrices have been obtained. For
PrF₃ the symmetric and asymmetric stretching modes were observed;
PrF₃ is accordingly assigned a...