Pure rotational spectra of the CO-trans-HOCO complex

摘要

Pure rotational spectra of the CO-trans-HOCO complex have been observed by Fourier transform microwave (FTMW) and millimeter-wave FTMW double resonance spectroscopy. The complex was produced in a supersonic jet by discharging a mixture gas of CO and H _2O diluted in Ar. The molecular constants including the fine and hyperfine coupling constants have been precisely determined. The inter-molecular distance between the CO and trans-HOCO monomers has been determined by fixing the structures of the trans-HOCO and CO monomers, where this complex has the OCHO configuration with the CHO angle almost linear. The CH distance, 2.166 ?, is much shorter than those of the closed shell complexes, CO-CH _3OH and CO-H _2O. The Fermi contact constant of the proton for the complex was compared with that of the trans-HOCO monomer, leading to a conclusion that there is almost no induced effect for the spin density on the proton of HOCO by the complex formation.