Rotational spectrum of 13C17O and 13C18O:: completely resolved nuclear hyperfine structures due to 13C and 17O

The pure rotational spectrum of (CO)-C-13-O-17 has been observed in the millimeter- and submillimeter-wave region using the Lamb-dip technique in order to increase the instrumental resolving power and so to resolve both the hyperfine structure due to O-17 and that due to C-13. In this way very accurate values of the rotational and centrifugal distortion constants, the O-17 nuclear electric quadrupole coupling constant and the O-17 and C-13 spin-rotation constants have been obtained. In addition, the J = 1 <-- 0 and J = 2 <-- 1 transitions of (CO)-C-13-O-18 have been recorded using the Lamb-dip technique. The resolved hyperfine structure of these transitions allowed us to determine the rotational and C-13 spin-rotation constants. The experimental determination of all these parameters has been supported by ab initio computations. (C) 2002 Elsevier Science (USA). All rights reserved.