Volume 126, Issue 10, 14 March 2007
Index of content:
126(2007); http://dx.doi.org/10.1063/1.2715544View Description Hide Description
Recently Afshari et al. reported on the detection of a new infrared band which was assigned to the “long-anticipated polar isomer of the OCS dimer” [J. Chem. Phys.126, 071102 (2007)]. The authors report here the microwave confirmation of their results. The lowest energy, nonpolar isomer of has long been known from IR spectroscopy, while the polar form has only been deduced from qualitative beam refocusing experiments. The higher energy, polar isomer of has been produced by high pressure expansion of dilute OCS in helium. A surprisingly strong microwave spectrum of has been observed and assigned.
Picosecond water dynamics adjacent to charged paramagnetic ions measured by magnetic relaxation dispersion126(2007); http://dx.doi.org/10.1063/1.2714942View Description Hide Description
Measurements of water-proton spin-lattice relaxation rate constants as a function of magnetic field strength [magnetic relaxationdispersion (MRD)] in aqueous solutions of paramagneticsolutes reveal a peak in the MRD profile. These previously unobserved peaks require that the time correlation functions describing the water-proton-electron dipolar coupling have a periodic contribution. In aqueous solutions of iron(III) ion the peak corresponds to a frequency of , which the authors ascribe to the motion of water participating in the second coordination sphere of the triply charged solute ion. Similar peaks of weaker intensity in the same time range are observed for aqueous solutions of chromium(III) chloride as well as for ion pairs formed by ammonium ion with trioxalatochromate(III) ion. The widths of the dispersion peaks are consistent with a lifetime for the periodic motion in the range of or longer.