The E1 and E2 strength in the electrofission of some heavy elements

Measurements of the electrofission cross section for ²³²Th, ²³⁸U and ²³⁷Np have been made for an electron energy range from 20 to 120 MeV. A comparison is made between the electrofission and photofission cross sections using the concept of virtual photons. It is deduced that the electrofission reaction for these elements proceeds through a significant E2 contribution as well as an E1 transition mode.     

Minimum path decompositions of oriented cubic graphs

Pullman [3] conjectured that if k is an odd positive integer, then every orientation of a regular graph of degree k has a minimum decomposition which contains no vertex which is both the initial vertex of some path in the decomposition and the terminal vertex of some other path in the decomposition. In this paper, the conjecture is established for cubic graphs, and its connection with Kelly's conjecture for tournaments is described.     

The hyperfine coupling tensors of muonated radicals in single‐crystal benzophenone

The hyperfine coupling tensors of muonated radicals in a large single crystal of benzophenone have been determined by measuring the hyperfine couplings of the radicals as the crystal was rotated about three orthogonal axes. Signals from four radicals were observed, corresponding to the four molecules per unit cell in the crystal. Due to an ambiguity in the data we are unable to discriminate between two similar hyperfine coupling tensors. Both lead to an isotropic hyperfine coupling of \sim32 MHz, contrasting with the solution value of 42 MHz obtained earlier in diethyl ether. The anisotropic components of the tensor are relatively large, at approximately -15 MHz, -6 MHz and 21 MHz, respectively. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ermakov systems,Noether's theorem and the Sarlet-Bahar method

We derive invariants for a nonlinear equation of motion containing arbitrary functions. The method employed is the recently discussed direct method of Sarlet and Bahar. The resulting invariants are a special case of Ermakov invariants. We compare these results to the results obtained by applying Noether's theorem to the same equation of motion.     

Photoelectron spectroscopy of S1 toluene: II. Intramolecular dynamics of selected vibrational levels in S1 toluene studied by nanosecond and picosecond time-resolved photoelectron spectroscopies

We present results which suggest that the photophysics of S(1) toluene is significantly more complicated than that of the related molecules p-fluorotoluene or p-difluorobenzene. We have measured a range of photoelectron spectra for a number of S(1) internal energies, on different time scales and at different temperatures, in an attempt to unravel the competing processes, but the final conclusion remains outstanding.     

Harmonic detection with tunable diode lasers —two-tone modulation

The minimum absorption detectable by a tunable diode laser spectrometer utilising harmonic techniques is often limited by interference fringes generated by scattered light. The sensitivity of the spectrometer to absorption can be increased by applying a jitter modulation. In this paper, the theory of harmonic response for single- and two-tone modulation over optical fringes and Lorentzian absorption lines is developed and compared to experimental measurements. A simple analytic expression for the two-tone harmonic line shape is derived. This expression provides a physical understanding of the effects of the second modulation, and a means to unravel the effects of the second modulation on the linewidth and line shape. For a specific choice of the jitter frequency and phase, it is possible to simultaneously minimise the fringe signal and increase the harmonic absorption signal. The results of this investigation are applicable to trace gas detection using tunable diode lasers, and to other areas of spectroscopy and magnetic resonance where harmonic techniques are used.This work was supported by the Natural Sciences and Engineering Research Council of Canada, and the Ontario Ministry of the Environment     

Uniform Asymptotic Approximations to the Solutions of the Orr-Sommerfeld Equation Part 2. The General Theory

This paper deals with the derivation of “first approximations” to the solutions of the Orr-Sommerfeld equation which are uniformly valid in a full neighborhood of the critical point. To this order the theory is remarkably simple. The essential elements in the theory are all well known from the older heuristic theories but its general structure is substantially different. The uniform approximations are also vastly simpler than the composite approximations obtained recently by the method of matched asymptotic expansions.     

A moiré fringe alignment aid

The task of accurately superimposing two photographic transparencies is frequently encountered in some areas of optical metrology. By recording a suitable line structure, along with the image, on each photograph, moiré fringes formed when two of the structures are superimposed can be used to give an accurate indication of the alignment of the transparencies.     

Bypasses in asymmetric digraphs

A digraph G is said to be asymmetric if uv ∈ G implies vu ? G. If uv ∈ G and P is a path of length k from u to v, then P is called a k-bypass from u to v. In this paper we investigate asymmetric digraphs in which each line has a 2-bypass. Results are obtained on the existence of such digraphs, the relationship between 2-bypasses and longer bypasses, and the question of how prevalent such digraphs are.