The infrared vibration—rotation spectrum of trans and cis nitrous acid

Infrared spectra of the trans and the cis isomers of nitrous acid, both HONO and DONO, have been observed in the gas phase using a Fourier transform interferometer with a resolution of about 0.05 cm^?1 from 4000 to 500 cm^?1. Rotational analyses are reported on eleven of the fundamentals and some overtones.     

[UIII{N(SiMe2tBu)2}3]: A Structurally Authenticated Trigonal Planar Actinide Complex

We report the synthesis and characterization of the uranium(III) triamide complex [U^III(N**)₃] [ 1 , N**=N(SiMe₂tBu)₂^?]. Surprisingly, complex 1 exhibits a trigonal planar geometry in the solid state, which is unprecedented for three‐coordinate actinide complexes that have exclusively adopted trigonal pyramidal geometries to date. The characterization data for [U^III(N**)₃] were compared with the prototypical trigonal pyramidal uranium(III) triamide complex [U^III(N“)₃] (N”=N(SiMe₃)₂^?), and taken together with theoretical calculations it was concluded that pyramidalization results in net stabilization for [U^III(N“)₃], but this can be overcome with very sterically demanding ligands, such as N**. The planarity of 1 leads to favorable magnetic dynamics, which may be considered in the future design of U^III single‐molecule magnets.     

Psychometric functions for gap detection in noise measured from young and aged subjects.

Psychometric functions for gap detection of temporal gaps in wideband noise were measured in a "yes/no" paradigm from normal-hearing young and aged subjects with closely matched audiograms. The effects of noise-burst duration, gap location, and uncertainty of gap location were tested. A typical psychometric function obtained in this study featured a steep slope, which was independent of most experimental conditions as well as age. However, gap thresholds were generally improved with increasing duration of the noise burst for both young and aged subjects. Gap location and uncertainty had no significant effects on the thresholds for the young subjects. For the aged subjects, whenever the gap was sufficiently away from the onset or offset of the noise burst, detectability was robust despite uncertainty about the gap location. Significant differences between young and aged subjects could be observed only when the gap was very close to the signal onset and offset.     

Low frequency surface resonance modes in electron energy loss spectroscopy

Electron energy loss spectroscopy has proved a powerful probe of vibrational modes of a wide variety of adsorbed species. Here the primary focus has been on modes with frequency well above the maximum phonon frequency of the substrate. Examples are internal vibration modes of adsorbed molecules, possibly shifted significantly in frequency from their gas phase analogues, and high frequency vibrations of an adsorbed molecule or atom against the substrate. Recent experiments explore features in the energy loss spectrum with frequency below the maximum phonon frequency of the substrate, for ordered overlayers of atoms adsorbed on low index metal surfaces. We shall summarize our theoretical studies of such spectra for several adsorbate/substrate combinations, with emphasis oh the physical origin of the features which appear in the calculations. We obtain a good account of the existing data, within the framework of a rather simple lattice dynamical model, and the calculations show that the features which appear are quite sensitive to the symmetry of the adsorption sits, and other details of the surface geometry. We shall illustrate this with several specific examples.     

Surface reconstruction and the Debye-Waller factor

A recently developed soft-mode theory of surface reconstruction¹ is used to calculate the surface Debye-Waller factor (SDWF) as a function of temperature near a supposed transition temperature (T₀) between two reconstruction patterns. The soft surface mode gives rise to a sharp decrease in the SDWF as T₀ is approached, suggesting that an examination the LEED Bragg intensities may help verify the soft mode theory.     

The two-dimensional anharmonic oscillator: The CCC bending mode of C3O2

Newly observed data on the rotational constants of carbon su?ide in excited vibrational states of the low-wavenumber bending vibration ν₇ have been successfully interpreted in terms of the two-dimensional anharmonic oscillator wavefunctions associated with this vibration. By combining these results with published infrared and Raman spectra the vibrational assignment has been extended and a refined bending potential for ν₇ has been derived: this has a minimum at a bending angle of about 24° at the central C atom, with an energy maximum at the linear configuration some 23 cm^?1 above the minimum. From similar data on the combination and hot bands of ν₇ with ν₄ (1587 cm^?1) and ν₂ (786 cm^?1) the effective ν₇ bending potential has also been determined in the one-quantum excited states of ν₄ and ν₂. The effective ν₇ potential shows significant changes from the ground vibrational state; the central hump in the ν₇ potential surface is increased to about 50 cm^?1 in the v₄ = 1 state, and decreased to about 1 cm^?1 in the v₂ = 1 state. In the light of these results vibrational assignments are suggested for most of the observed bands in the infrared and Raman spectra of C₃O₂.     

The Determination of Local Government Electoral Boundaries

For British local government elections, it is necessary to divide the total voting population into sub-groups (wards) such that each sub-group elects one or more representatives. At present there are remarkably few legal requirements governing the way in which this division is done. This study emphasizes the difficulties of formulating the problem of division, puts forward criteria which (hopefully) would look respectable and acceptable if embodied in legislation, and develops a linear programming-plus-heuristics approach which is applied to Bristol County Borough data to enable comparisons with current ward boundaries.