Millimetre-wave spectrum of HC17O+. Experimental and theoretical determination of the quadrupole coupling constant of the 17O nucleus

The millimetre-wave spectrum of HC17O+ has been analyzed up to 348.2 GHz by recording the J = 2 -1 and J = 4 -3 rotational transitions. Present measurements and the previous detection of the J = 1 -0 transition carried out in this laboratory allowed us to determine accurate values of the rotational and centrifugal distortion constants, and of the nuclear quadrupole coupling (c) and spin-rotation constants. Moreover, c has been evaluated from the electric field gradient at the oxygen nucleus calculated by using the multiconfiguration self-consistent field approach plus subsequent multireference configuration interaction computation, employing basis sets of quadruple zeta quality. Excellent agreement with experiment has been obtained. In addition, the molecular dipole moment has been calculated at the same level of accuracy