15min:

ZYGMUNT J. JAKUBEK AND BENOIT SIMARD, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6.

AlND₃ complexes are produced in a Smalley-type laser ablation source and probed by resonance 2-photon ionization technique. In the range 18500-23500 cm^-1, several vibronic bands for five isotopomers, Al¹⁴NH₃, Al¹⁵NH₃, Al¹⁴ND₃, Al¹⁴NHD₂, and Al¹⁴NH₂D, are observed. Only the AlND₃ complex is studied in detail. The spectrum is assigned to the B²A₁--X²E electronic transition, with the B²A₁ and X²E states correlating to the Al(4s)+ND₃(¹A₁') and Al(3p)+ND₃(¹A₁') asymptotes, respectively. The AlND₃ complex has approximate C_3v symmetry in both states. The origin band of the B²A₁--X²E transition is located at 18532.5\pm 1.0 cm^-1. The spin-orbit splitting of the ground state is determined to be 55.7\pm 0.4 cm^-1. Frequencies of the ₃ (Al-ND₃ stretch), ₄ (AlN-D₃ symmetric stretch), and ₆ (Al-ND₃ bend) vibrations in the B²A₁ state are measured to be 315.7\pm 0.6 cm^-1, 2657\pm 1 cm^-1, and 411\pm 1 cm^-1, respectively. Partially resolved rotational structure of some of the bands is observed and analyzed. The adiabatic ionization potential of the AlND₃ complex is measured by photoionization efficiency technique as equal 39710\pm 10 cm^-1. Rydberg series converging to various levels of the Al⁺-ND₃ stretching mode of the AlND₃⁺ cation are observed. The ₃⁺ frequency is determined to be 322 cm^-1. The structure determination of the neutral and monopositive complex and assignment of vibrational modes are aided by ab initio calculation.