Organic electrosynthesis ambident substitution reactivity of cyano-alkanes: electrochemically-directed αC-alkylation by bromo-alkanes

The formation of $\text{N}$-monoalkylacetamides through the electrolysis of bromoalkanes in cyanoalkanes at 2.35V is largely suppressed at higher electrode potentials in favour of a synthetically more useful α$\text{C}$-alkylation process.     

Vibrational relaxation studies in electron-beam excited Krf1

The recovery of the gain in electron-beam pumped krypton fluoride has been investigated following saturation with a pulse from a discharge pumped KrF laser. Vibrational relaxation in KrF¹ is found to occur on a subnanosecond timescale under typical laser conditions and the gain recovers in a time which is approximately equal to the fluorescence decay time.     

Design of optical polarization splitters in a single-section deeply etched MMI waveguide

The design of a single-section polarization splitter in a deeply etched semiconductor MMI waveguide is presented. Numerically simulated results indicate that the semiconductor MMI exhibits considerable polarization dependence and, utilizing this effect, a compact 1.6-mm-long polarization splitter may be fabricated to yield more than 8-dB polarization separation and only 0.11-dB optical loss, using a very simple design-approach. Received: 16 May 2001 / Revised version: 14 August 2001 / Published online: 2 November 2001     

Measurement of decay time based on FFT

Decay time is an important parameter in fluorescence temperature and pH value measurement. Many approaches are developed based on different principles. The decay acquisition and estimation method is one of them. A novel estimation method is given in this paper, based on the fast Fourier transform (FFT). The decay time can be calculated from the frequent items of the FFT. The advantages of this method include high accuracy, quick processing, independence on base offset etc. A set of experiment results is obtained based on this method.     

Photophysical parameters for potential vapour-phase dye-laser media

The fundamental photophysical parameters of the organic scintillators, anthracene, 9, 10 dimethyl antracene (DMA), 9, 10 diphenyl anthracene (DPA), 2-(1-napthyl)-5-phenyloxazole (α-NPO) and 2, 2′-p-phenyl bis (5-phenyloxazole) (POPOP), were investigated in the liquid and vapour phases. Their ground state, triplet-triplet and fluorescence spectra were determined and accurate extinction coefficients obtained. Photodecomposition of POPOP vapour under 337 nm excitation was investigated in detail and a photodecomposition quantum yield of 1.1×10⁻² obtained at 568 K. The POPOP triplet state in the vapour phase is quenched by the addition of 1, 3, 5, 7 cyclo-octatetraene and a quenching rate constant of 2.9×10¹⁰ M⁻¹ s⁻¹ was determined.