High-resolution infrared spectrum and energy levels of the weakly bound complex, CO-orthoD(2)

The infrared spectrum of the weakly bound complex CO-orthoD(2), which accom panies the fundamental band of CO in the 4.7 mu m region, has been recorded at high resolution using a long-path (approximate to 200 m), low-temperatu re (approximate to 47 K), absorption cell coupled either with a Fourier tra nsform spectrometer or with a tunable infrared diode laser. A total of 275 transitions, constituting most (> 85%) of the observed lines, have been rot ationally assigned in terms of 83 discrete quantum states of the complex. T he positions of most of these energy levels have been accurately determined (< 0.001 cm(-1)) for both the v(CO)=0 and 1 vibrational states. The bindin g energy of the complex, relative to the zero-point level, was determined t o be about 30 cm(-1). Predicted microwave and millimeter wave frequencies a re given for the pure rotational spectrum. The energy level pattern derived here, together with that determined previously for the analogous CO-paraH( 2) complex, provides direct and precise information for testing and refinin g the intermolecular potential energy surface of the carbon monoxide-hydrog en system. (C) 2000 American Institute of Physics. [S0021-9606(00)02021-3].