Showing papers by "Rodney S. Ruoff published in 1987"

Rotational spectra and structures of the Ar2–H35Cl/37Cl trimers

Abstract: Microwave rotational spectra have been observed for both Cl isotopes of the Ar2–HCl trimer with the pulsed nozzle Fourier transform method using the Flygare Mark II spectrometer. The Cl nuclear quadrupole hyperfine structure was analyzed for each of the transitions and the coupling constants and line centers determined. Sixteen transitions were observed in the 2 to 15 GHz region for the 35Cl species and 11 for 37Cl. The line centers were fitted to obtain ground state rotational and quartic centrifugal distortion constants A‘, B‘, C‘, τ1, τ2, τaaaa, τbbbb, and τcccc. For Ar2–H35Cl, the values are 1733.857, 1667.932, 844.491, −0.1170, −0.0292, −0.1199, −0.0802, and −0.0079 MHz, respectively, and for Ar2–H37Cl: 1733.824, 1606.877, 828.497, −0.1121, −0.0279, −0.1205, −0.0737, and −0.0075 MHz. The equilibrium geometry is determined to be T shaped with C2v symmetry and the H end of the HCl closest to the Ar2. Large amplitude slightly anisotropic torsional motion of the HCl is evident from the hyperfine constant...

Rotational spectrum and structure of the Ar3–HCl symmetric top

Abstract: The Ar3–HCl tetramer has been identified via the observation of its microwave rotational spectrum using the pulsed nozzle Fourier transform technique. The rotational spectroscopic constants of the ground vibrational state have been obtained for the 35Cl/37Cl isotopes from measurements of the J=1→2 to J=4→5 transitions and their hyperfine structure. For Ar3–H35Cl, the values found for B0, DJ, DJK, and χaa are 843.8974(1) MHz, 2.333(2) and 1.818(6) kHz, and 31.006(5) MHz, respectively, and for Ar3–H37Cl, 825.9811(2) MHz, 2.211(5) and 1.940(12) kHz, and 24.481(8) MHz. The cluster is a symmetric top with the HCl along the C3 axis, its H end directed towards the Ar3 trimer. In its torsional oscillations, the HCl makes an average angle of 36.91° with the symmetry axis. The chlorine isotopic substitution leads to values of 3.8510 and 4.0024 A for the Ar–Ar and Ar–Cl distances. The results of the present study are compared with those reported earlier for the Arm–HF (m=1,2,3) and Arm–HCl (m=1,2) clusters.