(1+1) REMPI spectroscopy and high-level ab initio study of the complex formed between NO and CO

A molecular complex between NO and CO has been observed for the first time. The results of two studies are reported: the (1 + 1) REMPI spectrum of the (A) over bar <--(X) over tilde transition and the results of high-level ab initio calculations [RCCSD(T)/aug-cc-pVQZ//UQCISD/6-311+G(3df)] on the (X) over tilde (II)-I-2 state. The indications are that the complex is compose d of two close-to-freely rotating diatoms. Comparison of the spectrum and t he results of the ab initio calculations suggests that the lowest energy is omer of the complex is not observed, or that possibly more than one isomer is present in the experiment. (C) 2001 Elsevier Science B.V. All rights res erved.