YbH and YbD molecules: ESR and optical spectroscopy in argon matrices at 4 °K

YbH and YbD molecules have been prepared by the reaction of Yb and H(D) atoms during the formation of an argon matrix at 4 °K. Yb atom and YbH absorption and emission spectra were observed. The magnetic parameters of YbH were determined from the ESR spectrum of the 2Σ molecules (with Yb nuclear spin I=0 and I=1/2) to be g∥=1.9953(4), g⊥=1.9402(2), A∥(H) =226 MHz, A⊥(H) =224 MHz, A⊥[171Yb (I=1/2)]=5266 MHz, A∥[171Yb (I=1/2)]=5724 MHz. The hyperfine parameters indicate that the spin density is less than 20% on the hydrogen and that the bonding is largely Yb+H−. By comparison of experimental parameters with calculated Yb and Yb+ data it is deduced that the unpaired electron occupies predominately the 6sσ orbital on Yb+ with smaller contributions of 6pσ (Yb+) and 1sσ (H−).