Knowledge Bank

Using millimeter wave absorption spectroscopy we have recorded pure rotation spectra of MgOH for the ground vibrational state and for six excited vibrational states. We have also determined a large number of bending vibrational energies, and the MgO stretching frequency, using dispersed fluorescence studies of both MgOH and MgOD. By a weighted least squares optimized fitting to this data using the variational approach $MORBID1$ Morse Oscillator Rigid Bender Internal Dynamics), with a basis set of Morse oscillator stretching functions and rigid bender functions, we have derived the full ground state potential surface in an analytical form. Although the equilibrium structure is determined to be linear, the bending part of the potential is rather flat and symptoms of quasilinearity are present; for example in the $\nu 2=2$ state the l = 2 component is below the l = 0 component.