Reactive ion etching of Ta-Si-N diffusion barriers in CHF3+O2

Reactive ion etching of Ta₃₆Si₁₄N₅₀ diffusion barrier layers was performed in CHF₃+O₂ plasmas. Etch depths and rates were determined as a function of etch gas composition, cathode power, and etching time. Etching proceeds only after an initial delay which depends on gas composition and cathode power. This delay is attributed to the presence of a native surface oxide which must first be removed before etching can commence. Maximum etch rate was attained at 62.5% O₂ concentration, which also corresponds to minimum delay     

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.     

Single-frequency travelling-wave erbium-doped fibre loop laser

A novel erbium-doped fibre laser cavity configuration with produces single-longitudinal-mode operation with less than 10 kHz linewidth is reported. The fibre laser operates in a travelling-wave mode which prevents spatial holeburning from occurring. A principal advantage of the configuration is that it allows the precise and stable setting of the lasing wavelength.<>     

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.     

Very broad reflection bandwidth (44 nm) chirped fibre gratings andnarrow bandpass filters produced by the use of an amplitude mask

Chirped gratings with very broad reflection bandwidths up to 44 nm and high reflectivity have been produced holographically in boron-codoped and standard telecommunications fibres which have been hydrogen-soaked. A 2 nm wide transmission band has been produced within the broad reflection band by use of an amplitude mask during grating exposure     

New infrared laser transitions in Ag II

We have observed seven infrared laser transitions when exciting a He discharge in a silver hollow cathode. To our knowledge, five of the seven laser transitions have not been reported previously in the literature.