Rotational spectrum and hydrogen bonding of the H2O-HO radical complex

The first spectroscopic identification of the H2O-HO radical complex in the gas phase has been conducted by utilizing pulsed-discharge nozzle Fourier transform microwave spectroscopy. R-branch transitions in the Ka = 0 manifold appeared as in Hund's case (b), but extraordinarily large spin doubling implies a strong spin-orbit coupling between the electronic ground and low-lying excited states that correlate to the degenerate 2Pi state in free OH. The geometry of the complex is of C2v symmetry as a zero-point vibrational average, in which the OH radical acts as a proton donor to water. Precisely determined hyperfine coupling constants associated with hydrogen nuclei indicate a substantial rearrangement in unpaired electron distribution: there exists small but nonzero spin density on the H atoms in water.     

Microwave spectra of deuterated ethanes: Internal rotation potential function and rz structure

The microwave spectra of CH₃CHD₂ in the first excited torsional state and of CH₃CH₂D and CD₃CH₂D in the ground states have been observed by a source-modulation spectrometer and analyzed to determine the two potential constants, V₃ and V₆, simultaneously and also to assess the isotopic effects on the potential function. The results obtained for C₂H₆ are V₃ = 2.882 ± 0.010 and V₆ = 0.020 ± 0.010 kcal/mole. The staggered conformation in ethane was established by observing microwave spectra of gauche CH₂DCH₂D. The r_z structure of ethane was recalculated by adding precise rotational constants obtained in this work to previous microwave and infrared data.     

Dual-plane stereoscopic particle image velocimetry: system set-up and its application on a lobed jet mixing flow

 The technical basis and system set-up of a dual-plane stereoscopic particle image velocimetry (PIV) system, which can obtain the flow velocity (all three components) fields at two spatially separated planes simultaneously, is summarized. The simultaneous measurements were achieved by using two sets of double-pulsed Nd:Yag lasers with additional optics to illuminate the objective fluid flow with two orthogonally linearly polarized laser sheets at two spatially separated planes, as proposed by Kaehler and Kompenhans in 1999. The light scattered by the tracer particles illuminated by laser sheets with orthogonal linear polarization were separated by using polarizing beam-splitter cubes, then recorded by high-resolution CCD cameras. A three-dimensional in-situ calibration procedure was used to determine the relationships between the 2-D image planes and three-dimensional object fields for both position mapping and velocity three-component reconstruction. Unlike conventional two-component PIV systems or single-plane stereoscopic PIV systems, which can only get one-component of vorticity vectors, the present dual-plane stereoscopic PIV system can provide all the three components of the vorticity vectors and various auto-correlation and cross-correlation coefficients of flow variables instantaneously and simultaneously. The present dual-plane stereoscopic PIV system was applied to measure an air jet mixing flow exhausted from a lobed nozzle. Various vortex structures in the lobed jet mixing flow were revealed quantitatively and instantaneously. In order to evaluate the measurement accuracy of the present dual-plane stereoscopic PIV system, the measurement results were compared with the simultaneous measurement results of a laser Doppler velocimetry (LDV) system. It was found that both the instantaneous data and ensemble-averaged values of the stereoscopic PIV measurement results and the LDV measurement results agree well. For the ensemble-averaged values of the out-of-plane velocity component at comparison points, the differences between the stereoscopic PIV and LDV measurement results were found to be less than 2%. Received: 18 April 2000/Accepted: 2 February 2001     

Spectral Properties of Schrödinger Operators on Perturbed Lattices

We study the spectral properties of Schrödinger operators on perturbed lattices. We shall prove the non-existence or the discreteness of embedded eigenvalues, the limiting absorption principle for the resolvent, construct a spectral representation, and define the S-matrix. Our theory covers the square, triangular, diamond, Kagome lattices, as well as the ladder, the graphite and the subdivision of square lattice.     

Observation of the pure rotational spectra of trans- and cis-HOCO

Pure rotational spectra of trans- and cis-HOCO have been observed by Fourier transform microwave spectroscopy and the millimeter-wave double resonance technique, where gas phase spectra of the cis-conformer were observed for the first time. These radicals were produced in a supersonic jet by discharging a mixture gas of CO and H(2)O diluted in Ar. The molecular constants including the fine and hyperfine constants have been precisely determined for both conformers. Deuterated analogs have also been observed. The determined r(0) structures agree with these of ab initio calculations. The Fermi contact constants show a difference of the unpaired electron densities on the protons between the two conformers. Intensity of the spectrum for cis-HOCO was compared with that of trans-HOCO, leading to a conclusion that both conformers were produced nearly equally in abundance under the present experimental conditions.     

Correlation effects among thermal displacements of atoms in KBr

Neutron diffraction measurements have been performed on powder KBr at 7 and 298 K. An oscillatory diffuse scattering intensity is observed at 298 K. The oscillatory scheme of the diffuse scattering intensity is explained by the values of correlation effects which are almost the same as those in other ionic crystals. The value of the correlation effects as suggested by earlier studies using EXAFS measurement cannot explain the observed diffuse scattering intensity. Force constants among first, second and third nearest neighboring atoms are obtained from the correlation effects and used to estimate the phonon dispersion curves by computer simulation.     

Direct simultaneous determination for ultratrace As, Se and Sb in river water with graphite-furnace atomic absorpion spectrometry by TiO2-slurry sampling.

A simple analytical method was established for the simultaneous multielement determination of As, Se and Sb in river water with GF-AAS using TiO2-slurry sampling. Titanium dioxide (TiO2, <0.5 microm) was applied as a sorbent to separate and concentrate these elements in a sample solution (100-300 ml); after filtration, a slurry was prepared with the solid phase and 5.0 ml of ultrapure water. In order to apply to river-water samples, the effect of TiO2 in atomization, the effect of organic species of their metal and the interference of foreign ions were investigated. The proposed method was applied to JSAC 0302 and river water.     

On N -body Schr?dinger operators

In these notes, we study the estimates of the resolvent or the unitary group of theN-body Schr?dinger operator. The main strategy is to introduce an algebra of operators having nice commutation relations with the many-body Schr?dinger operator. These estimates are applied to derive the detailed properties of the S-matrices associated with the many-body collision process.