Emission topography of a stable spark discharge train

Time and space resolved spectroscopy are used to photograph the emission from a stable spark discharge train attacking a rotating copper beveled disk in flowing argon. The spark is generated at 60 Hz with a Bardocz type adjustable waveform source. Photographic density over background of sets of lines in the Cu I and Cu II term system is plotted as a function of lateral displacement from the vertical interelectrode axis and time at discrete horizontal distances away from the copper cathode surface to form spatially connected sets of lateral emission profiles. Data from secondary cathodes of silver and gold are presented, along with spectral evidence for radial compression of the cathode jets accompanying their charge transfer ionization and excitation. Spectrochemical applications utilizing time-space structural details are discussed.     

Determination of the magnetic dipole moment of114Sb Via on-line nuclear orientation

The magnetic dipole moment of¹¹⁴Sb has been measured using on-line nuclear orientation (OLNO) at the UNISOR Nuclear Orientation Facility (UNISOR/NOF). The value was determined to be 1.72 (8) nuclear magnetons. The observed anisotropy of the 1299 keV transition was fitted as a function of temperature making allowance for incomplete thermalization of the¹¹⁴Sb nuclei prior to decay. The relaxation constant, C_k, is discussed, as is the ground state structure of¹¹⁴Sb.     

Electron impact ionization of the noble gases in coplanar symmetric geometry over the energy range 100 to 1000 eV

Distorted-wave Born approximation calculations are reported for electron impact ionization of He, Ne, Ar, Kr and Xe in coplanar symmetric geometry at energies of 100, 500 and 1000 eV. Of special interest is double scattering effect at large angles.     

Simulation model for anomalous precession of the perihelion of mercury's orbit

The ‘anomalous perihelion precession’ of Mercury, announced by Le Verrier in 1859, was a highly controversial topic for more than half a century and invoked many alternative theories until 1916, when Einstein presented his theory of general relativity as an alternative theory of gravitation and showed perihelion precession to be one of its potential manifestations. As perihelion precession was a directly derived result of the full General Theory and not just the Equivalence Principle, Einstein viewed it as the most critical test of his theory. This paper presents the computed value of the anomalous perihelion precession of Mercury's orbit using a new relativistic simulation model that employs a simple transformation factor for mass and time, proposed in an earlier paper. This computed value compares well with the prediction of general relativity and is, also, in complete agreement with the observed value within its range of uncertainty. No general relativistic equations have been used for computing the results presented in this paper.     

Thermostated radio-frequency excited electrodeless discharge lamps as primary sources in AFS

The performance of Cd and Zn thermostated electrodeless discharge lamps (EDL's) excited at 150 MHz radio-frequency through the inductively-coupled mode in a coil, have been studied with respect to the effect of lamp temperature, amount of material and RF power upon the source radiant output, atomic absorption, atomic fluorescence signals, spectral line width and line profile height of Cd 479.99 nm, Cd 228.8 nm, Zn 481.05 nm and Zn 213.9 nm. Although the lamps show similar behaviour to their microwave excited counterparts, they nevertheless offer several advantages that could renew the interest in EDL's as primary excitation sources in analytical spectroscopy.     

The unsteady motion of a sphere in an elastico-viscous liquid

Summary Consideration is given to the unsteady motion of a sphere moving under a constant force in elastico-viscous liquid, the sphere being initially at rest. The problem is solved by the familiarLaplace-transform method. It is shown that the presence of elasticity in the liquid increases the velocity of the sphere. This increase is very pronounced for small values of the time, but is not very significant for large values of the time. It is concluded that the time taken to reach the terminal velocity is unaffected by the presence of elasticity in the liquid.Formulae are given which may be of use to experimentalists who use the falling-ball method to determine the zero shear-rate viscosity.     

Configurationally stable longitudinally twisted polycyclic aromatic compounds

Two strategies for the synthesis of configurationally stable twisted polycyclic aromatic compounds (PACs) were pursued. The first approach employed dissymmetrically positioned 1-naphthyl substituents to bias the direction of twist in highly substituted PACs. 2,3-Bis(1-naphthyl)-1,4-diphenyltriphenylene (7) was prepared, and its meso cis-dinaphthyl and enantiomeric trans-dinaphthyl isomers were resolved by preparative supercritical fluid chromatography (SFC) on chiral supports. Similarly, several naphthyl-substituted derivatives of the more highly twisted 9,10,11,12,13,14-hexaphenylbenzo[b]triphenylene (2) were prepared. Of these, 10-(1-naphthyl)-9,11,12,14-tetraphenylbenzo[b]triphenylene (13) was resolved by SFC on a chiral support. The pure enantiomers of trans-7 showed moderately large specific rotations ([alpha]D(25) = -330 and +320 degrees), but the specific rotations for the enantiomers of 13 were unexpectedly small ([alpha]D(25) = -23 and +23 degrees). Computational studies suggest that the latter result is due to presence of a minor conformation of 13 possessing a larger rotation of opposite sign than the major conformation. Both 7 and 13 showed strong circular dichroism and moderately strong circularly polarized luminescence. A byproduct of these syntheses was 9,10,19,21-tetraphenyldiphenanthro[9,10-b:9,10-h]carbazole (15), a very crowded carbazole that exhibits an 81 degree end-to-end twist but is not resolvable. In the second approach, the large, twisted, polycyclic aromatic ligand 9,10,11,12,13,14-hexaphenylbenzo[h]naphtho[2,3-f]quinoline (21, an aza-2) was used to prepare the chiral, cyclometallated iridium(III) complex 4. The ligand 21 was prepared via an unusually stable benzannulated norbornadienone, for which the free energy of activation for decarbonylation was a remarkable 33.5 kcal/mol. The iridium complex 4 proved to be configurationally stable and resolvable by analytical HPLC on chiral supports, but the low solubility of 4 prevented its resolution on a preparative scale. A much more soluble dibutyl analogue of 4 (complex 28) was then prepared, but it was not resolvable on any of the available media.