EXPERIMENTAL AND THEORETICAL STUDY OF THE BOUND-FREE $G^{2}\Sigma (4p) \leftarrow X^{2}\Pi (3p)$ TRANSITION OF AlAr

Author Institution: A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology; Air Force Research Laboratory, OLAC PLIRKSThe $G^{2}\Sigma (4p)$ state of AlAr has been observed by both 1+1 and 2+1 resonant multiphoton ionization from the $X^{2}\Pi (3p)$ state. The G state is a dissociative state resulting in a broad but asymmetric band peaked at $33920 cm^{-1}$, detectable by action spectroscopy upon one- and two-photon absorption. The atomic Al 3p-4p transition is forbidden, and molecular AlAr transitions between states arising from these states are primarily two-photon in character due to the weak mixing of Al-atom configurations. Simulations of both the one- and two-photon bands using ab initio potential curves and dipole moment functions calculated by MR-Cl methods are in good agreement with observations