Raman and absorption spectrum of mass-selected lutetium dimers in argon matrices

We report on the absorption, resonance Raman, and Raman excitation profile spectra of mass selected lutetium dimers in argon matrices. Two broad absor ption regions were found between 415 and 545 nm with peaks at 418, 433, 452 , 472, 505, 540 nm, and between 635 and 660 nm with peaks at 640 and 652 nm . Resonance Raman spectra were obtained by excitation into one of these reg ions with the visible light of an Ar ion laser between 458 and 514 nm. Two progressions were assigned to lutetium dimers. We interpret them to represe nt two distinct electronic states: A ground-state X and an excited state A. For the ground (X) state, we obtain omega (e)=121.6 +/-0.8 cm(-1) with ome ga (e)x(e)=0.16 +/-0.10 cm(-1), leading to a spectroscopic dissociation ene rgy of 2.9 +/-1.8 eV, and force constant k(e)=0.76 +/-0.01 mdyne/Angstrom. The lowest excited electronic state (A) has an origin at 210.7 cm(-1) and a lmost identical vibrational parameters. Comparison of spectroscopic propert ies of lanthanide dimers is discussed, and evidence is presented that lutet ium should occupy the position normally given to lanthanum in the periodic table. (C) 2000 American Institute of Physics. [S0021-9606(00)01546-4].