Extended homogeneous nanoripple formation during interaction of high-intensity few-cycle pulses with a moving silicon wafer

We report the study of extended nanoripple structures formed during the interaction of high-intensity 3.5 fs pulses with a moving silicon wafer. The optimization of laser intensity (8×10¹³ W?cm^?2) and sample moving velocity (1 mm?s^?1) allowed the formation of long strips (～5 mm) of homogeneous nanoripples along the whole area of laser ablation. The comparison of nanoripples produced on the silicon surfaces by few- and multi-cycle pulses is presented. We find that few-cycle pulses produce sharp and more homogenous structures than multi-cycle pulses.     

Application of an ephedrine chiral linker in a solid-phase, 'asymmetric catch-release' approach to gamma-butyrolactones

A Sm(II)-mediated, asymmetric, intermolecular ketyl-olefin addition employing alpha,beta-unsaturated esters linked to resin through an ephedrine 'chiral link' has been applied in a direct 'asymmetric catch-release' approach to gamma-butyrolactones.     

Nuclear Orientation Studies of Magnetism in Single Crystal Pr0.5Nd0.5Ni

The angular distributions of -rays from ¹⁴²Pr, ¹⁴⁷Nd and ¹⁴⁴Pm in Pr_0.5Nd_0.5Ni were investigated by means of low-temperature nuclear orientation. The results show that the Pr and Nd electronic moments order along the c- and a-axis, respectively. Pm ions introduced as a very dilute magnetic impurity, preferentially align with the Nd ions.     

Homogeneity of Lanthanide Doped Ceria Nanocrystal Dispersions Using High-resolution Transmission Electron Microscopy

Aqueous sols of crystalline solid solutions of the general formula Ce_1-xLn_xO_2-x/2x/2 [Ln = entire lanthanide range, x = 0–0.50 and square = anion vacancy] were synthesised using inorganic materials. The nanocrystals were dispersed on an amorphous silica support and individual crystals examined for composition and structure by high-resolution transmission electron microscopy (HREM) and energy dispersive analysis of X-rays (EDX). High-resolution pictures showed the nanocrystals to be mainly between 5 and 10 nm in size, rarely elongated and with atomically clean faceted surfaces.Diffractograms were used to measure the lattice parameters of the face-centre-cubic (fcc) fluorite structures giving values, depending on dopant species and concentration of dopant, in the range 5.5–5.8 Å. EDX analysis of individual crystals with the same nominal composition compared closely to each other and to that of an average over a large area indicating good homogeneity from the preparation method.     

Orthogonal Polynomials and Second-order Differential Equations

We show that a sequence of polynomials can be eigenfunctionsof a second-order differential operator only under severe restrictions.     

Structural, photonic band-gap, and luminescence properties of the opal-erbium composite

Erbium oxide and silicates were embedded in the pores of synthetic opal by using the chemical bath deposition technique. Electron-microscopic images showed the synthesized compounds to be deposited predominantly in a thin uniform layer on the inner surface of the pores. An analysis of the transmittance spectra suggested that the opal-erbium composite thus obtained retained the photonic band-gap properties of the original ordered opal matrix. The Er³⁺ ions in the composite emitted light at several wavelengths in the visible and near-IR regions (550, 860, 980, 1240, 1530 nm) at 80 K.     

The study of structure by electron magnetic resonance methods. A brief history

An overview of the use of EPR in the determination of structure is given.     

Sign of excited state nuclearg-factors using gamma detected NMR/ON

Integral nuclear orientation and conventional CW NMR/ON studies using parity conserving gamma radiation can yield the nuclear moment μ, g and hence the nuclear spin, I, of the radioactive parent nuclei, but not the sign of g. In principle, the sign of g is accessible using parity non conserving beta radiation but is technically difficult; also, some nuclei decay without particle emission. We describe a novel spin echo NMR/ON technique that overcomes these previous difficulties and allows determination of the sign of the g-factor using gamma radiation.     

Nuclear magnetic resonance pulse sequence and discrimination of high- and low-fat tissues

Signal size compared to independently measured T1 is described for various pulse sequences on the Aberdeen Mk II nuclear magnetic resonance imager. The ability of these sequences to discriminate between certain tissue types, and in particular between adipose tissue and muscle, is discussed. Inversion recovery, with a t interval of 200 ms, gives the best discrimination for this purpose, with a contrast ratio of 6 between fat and muscle. Other image types, and especially T1, give better contrast for low-lipid soft tissue such as liver and spleen.