Laser spectroscopy of the A9–X8 transition of holmium monochloride

The pure rotational spectrum of 13C17O 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 17O and that due to 13C. In this way very accurate values of the rotational and centrifugal distortion constants, the 17O nuclear electric quadrupole coupling constant and the 17O and 13C spin–rotation constants have been obtained. In addition, the J=1-0 and J=21 transitions of 13C18O have been recorded using the Lamb-dip technique. The resolved hyperfine structure of these transitions allowed us to determine the rotational and 13C spin–rotation constants. The experimental determination of all these parameters has been supported by ab initio computations.