Electronic spectroscopy of jet-cooled YbNH3.

We report the first spectroscopic study of a complex consisting of a rare earth atom in combination with ammonia. Using two-color resonance-enhanced multiphoton ionization (REMPI) spectroscopy, the lowest energy electronic transition of YbNH(3) has been found in the near-infrared. The spectrum arises from a spin-forbidden transition between the (1)A(1) ground electronic state and the lowest (3)E excited electronic state. The transition is metal centered and approximately correlates with the Yb 6s6p (3)P ← 6s(2) (1)S transition. The observation of clear spin-orbit structure in the spectrum confirms the C(3v) symmetry of YbNH(3). Vibrational structure is also observed in the REMPI spectrum, which is dominated by excitation of the Yb-N stretching vibration.