HIGH-RESOLUTION EMISSION-SPECTROSCOPY OF ALCL AT 20-MU

The high resolution infrared emission spectrum of aluminum monochloride has been recorded with a Fourier transform spectrometer. A total of 1747 rovibrational transitions, upsilon = 1 --> 0 to upsilon = 8 --> 7, for the most abundant isotopomer (AlCl)-Al-27-Cl-35 and 708, upsilon = 1 --> 0 to upsilon = 4 --> 3, for the least abundant isotopomer (AlCl)-Al-27-Cl-37 have been assigned. This new set of infrared data was combined with existing microwave and millimeter-wave data to refine the Dunham Y(ij) constants for the X1SIGMA+ electronic ground state. In addition two sets of mass-reduced Dunham U(ij) constants have been determined from separate fits. In the first fit all of the U(ij) constants that could be statistically determined were treated as adjustable parameters. In the second fit only the constants satisfying the condition j < 2 were treated as adjustable parameters while the values for the remaining constants were fixed to constraints imposed by the Dunham model. Finally, in order to fully utilize the information provided by this extensive data set in an attempt to improve the prediction of energies for higher lying upsilon, J levels of the X1SIGMA+ state, the combined data set, consisting of microwave, millimeter, and infrared (IR) data were fitted directly to the eigen-values of the Schrodinger equation containing a parametrized internuclear potential energy function.