Saturation spectroscopy of BO2 at 5145 Å

The hyperfine structure of one of the transitions of BO₂ coincident with the 5145 Å argon-ion laser line has been resolved by the technique of intermodulated fluorescence. The splitting has been interpreted in terms of the hyperfine constants of the excited A ²Π_u electronic state.     

Controlling surface roughness in vapor-deposited poly(amic acid) films by solvent-vapor exposure

A series of vapor-deposited poly(amic acid) (PAA) films were exposed to dimethyl sulfoxide (DMSO) vapors to investigate sorption kinetics and surface smoothing phenomena. Gravimetric sorption and secondary-ion mass spectrometry (SIMS) results are both consistent with frontal (case II) diffusion. These experiments suggest that the solvent front is defined by a sharp interface that delineates the swollen material from the unswollen material. Solvent-vapor smoothing was studied by first depositing PAA onto rough aluminum surfaces, and then, during solvent-vapor exposure, the surface topology was continuously monitored using a light interference microscope. The resulting time-dependent power spectra indicate that high-frequency defects smooth faster than low-frequency defects. This frequency dependence was further investigated by depositing PAA onto a series of sinusoidal surfaces and exposing them to solvent vapor inside a flow channel. The sinusoidal amplitudes decay exponentially with time, with decay constants that are proportional to the surface frequency. To explain the physics of surface smoothing, a two-parameter model is presented and agrees qualitatively with experimental data.     

Quadrupole deformation of the self-conjugate nucleus 72Kr

We report on the first determination of the absolute B(E2;0+(1)-->2+(1)) excitation strength in the N=Z nucleus 72Kr. 72Kr is the heaviest N=Z nucleus for which this quantity has been measured and provides a benchmark in a region of the nuclear chart dominated by rapidly changing deformations and shapes mediated by the interplay of strongly oblate and prolate-driving orbitals. The deduced quadrupole deformation strength is in agreement with a variety of self-consistent models that predict an oblate shape for the ground state of 72Kr. Large-scale shell-model Monte Carlo calculations reproduce the experimental B(E2) value and link the result to the occupation of the deformation-driving g9/2 orbit.     

Observation of the 1S0-3P0 transition in atomic ytterbium for optical clocks and qubit arrays

We report an observation of the weak 6 1S0-6 3P0 transition in (171,173)Yb as an important step to establishing Yb as a primary candidate for future optical frequency standards, and to open up a new approach for qubits using the 1S0 and 3P0 states of Yb atoms in an optical lattice.     

Investigation of the proton migration mechanism in the perovskite proton conductor Ba3Ca1.18Nb1.82H0.2O8.83 by means of quasielastic neutron scattering

We investigated the recently discovered high temperature proton conductor BaCa_1.18Nb_1.82H_0.2O_8.83 by means of quasielastic neutron scattering (QENS) using cold and thermal neutrons. From the former experiment we were able to propose models for the diffusion of the hydrogen whereas the latter measurement reveals the geometry of a localized motion of the protons. Paper presented at the 2nd Euroconference on Solid State Ionics, Funchal, Madeira, Portugal, Sept. 10–16, 1995     

Structural characterisation of a red phthalocyanine

Metal 1,4,8,11,15,18,22,25-octakis(hexylsulfanyl)phthalocyanines exhibit a weak absorption band in the 450-600 nm region, leading to novel dyes that include the red lead metallated derivative that has been characterised by X-ray crystallography.     

1,4-dibutoxy-2,3-di(4-pyridyl)-8,11,15,18,22,25-hexakis(hexyl)- phthalocyaninato zinc,a self-assembled coordination polymer in the solid state

The title compound forms intermolecular zinc-nitrogen coordinated species in solution and self-assembles to form a coordination polymer in the solid state, the X-ray structure for which shows that the unit cell contains eight macrocycle units in two chains comprising both enantiomeric forms as ABBA/BAAB sequences.     

Improved direct measurement of leptonic coupling asymmetries with polarized Z bosons

We present final measurements of the Z boson-lepton coupling asymmetry parameters A(e), A(mu), and A(tau) with the complete sample of polarized Z bosons collected by the SLD detector at the SLAC Linear Collider. From the left-right production and decay polar angle asymmetries in leptonic Z decays we measure A(e) = 0.1544+/-0.0060, A(mu) = 0.142+/-0.015, and A(tau) = 0.136+/-0.015. Combined with our left-right asymmetry measured from hadronic decays, we find A(e) = 0.1516+/-0.0021. Assuming lepton universality, we obtain a combined effective weak mixing angle of sin (2)theta(eff)(W) = 0.230 98+/-0.000 26.     

Effect of a 17alpha-(3-hydroxypropyl)-17beta-acetyl substituent pattern on the glucocorticoid and progestin receptor binding of 11beta-arylestra-4,9-dien-3-ones

[structure: see text]. Replacing the 17alpha-acetoxy substituent in an antiprogestational 17beta-acetyl-11beta-arylestra-4,9-dien-3-one by 3-hydroxypropyl significantly diminished glucocorticoid receptor binding with little effect on progestin receptor binding.