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Better pulp quality control, especially relating to product sheet strength, can offer an important means to improve the market superiority of a pulp. However, aside from lignin content, few pulp properties can be easily measured in a timely manner for process control. The present report proves a principle on a novel Raman system and a systematic chemometric approach, allowing for rapid spectral data acquisition and definitive spectrochemical analysis of wet pulp under harsh manufacturing conditions. By incorporating sophisticated chemometrics strategies that combine wavelet transform with a tem-plate-oriented genetic algorithm feature selection and partial least squares multivariate classification, this instrument system extracts maximum analytical information from raw Raman spectra to accurately predict the physicomechanical properties of sheet products. Our work has tested and refined these routines by drawing upon the systematic analysis of 26 bleached soft-wood kraft pulps formulated to yield challenges representative of those encountered in common pulp fibre and sheet analyses. Satisfactory calibration results suggest that a Raman gauge can be developed that has the capacity to continuously assay pulp to predict the physicomechanical properties of sheet paper in real time. Un meilleur controle de la qualite de la pate, particulierement en lien avec la solidite du papier en feuille, peut of-frir un moyen important pour augmenter la superiorite de la pate sur le marche. Cependant, mis a part la teneur en lignine, peu de proprietes de la pate peuvent etre facilement mesurees assez rapidement pour la commande de processus. Cet article demontre le principe d'un nouveau systeme Raman et d'une approche chimiometrique systematique qui permet l'acquisition rapide de donnees spectrales et l'analyse spectrochimique definitive de la pate humide dans des conditions de fabrication difficiles. En incorporant des strategies sophistiquees de chimiometrique qui combinent la transformation en ondelettes avec la selection de caracteristiques au moyen d'algorithmes genetiques bases sur un gabarit et la classification multivariee par les moindres carres partiels, ce systeme instrumental extrait un maximum d'information analytique a partir des spectres bruts de Raman pour predire avec precision les proprietes physicomecaniques du papier en feuille. Nous avons teste et raffine ces routines en se basant sur l'analyse de 26 pates kraft blanchies de resineux formulees de maniere a offrir des defis representa-tifs de ceux que l'on rencontre dans l'analyse courante des pates de fibre et du papier en feuille. Des resultats de calibration satisfaisants indiquent qu'il est possible de mettre au point une jauge Raman capable de tester en continue la pate pour predire les proprietes physicochimiques du papier en feuille en temps reel. [Traduit par la Redaction], Introduction Raman spectroscopy offers a unique means to rapidly measure pulp fibre properties and processing-related changes in these properties, nondestructively, with little or no sample preparation and little sensitivity to [...]

The output of a frequency-tripled, pulsed dye laser was used to extend the ionization-detected one-photon absorption spectrum of HCO to include higher excited vibronic levels of the 3pPi (super 2)Pi Rydberg state in the interval from 47 900 to 50 500 cm. Transition energies determined by calculations using the spectroscopic constants were compared with experimental observations.

Two-color, two-photon resonant, three-photon ionization, and high-resolution photoelectron spectroscopy were combined to characterize the photoionization dynamics of the 3p sigma (super 2)sigma(sub u)(super +) electronic state of the NO(sub 2). Direct photoionization of selected vibrational levels of the NO(sub 2) 3p sigma (super 2)sigma(sub u)(super +) showed a strong propensity to preserve the vibrational quantum numbers of the intermediate state.

Molecules with electronically degenerate ground states confound conventional notions of molecular shape and the ball-and-stick separability of electronic and internuclear degrees of freedom. Nuclear motions coupled with electronic degeneracy link [...], The benzene molecule serves as a benchmark among the aromatic hydrocarbons and has been the subject of numerous experimental and theoretical studies. Despite such intensive investigations, the precise structure of the benzene cation ([C.sub.6][H.sub.6][sup.+]) is not known. Now, experiments measuring high-resolution state-to-state threshold photoionization spectra of benzene concretely establish the terms of vibronic levels in the distorted cation that are split by higher order Jahn-Teller coupling between its ²[E.sub.1g] electronic ground state and [v.sub.6] [e.sub.eg] in-plane ring-bending vibrational mode. This assignment, in turn, sets the absolute energy phase of the vibronic pseudorotation in this coordinate and thereby offers a definitive experimental determination of the shape of the benzene cation.

Mass spectrometry is undergoing rapid development, especially with the extension of its range into the hundreds of kilodaltons, the emergence of the quadrupole ion trap as a high-performance instrument, and [...]

Triple-resonance excitation and high-resolution photoelectron spectroscopy are combined to characterize the mode selectivity of vibrational autoionization of the high Rydberg states of NO[sub 2]. Photoelectron spectra and vibrational branching fractions are reported for autoionizing Rydberg states converging to the NO[sub 2][sup +] X [sup 1]Σ[sub g][sup +](110) state, that is, with one quantum in the symmetric stretch, ν[sub 1], and one quantum in the bending vibration, ν[sub 2]. These results indicate that autoionization proceeds most efficiently through the loss of one quantum from the symmetric stretch rather than from the bending vibration. The implications of this result are discussed in terms of the autoionization mechanism. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Important challenges remain for sustainable design, manufacture, use, and recycling of electronics including materials selection and disassembly time. This paper examines the value relationship between the quantity of plastics separated and the time required for disassembly and segregation. Labor costs for disassembly can constitute a large portion of the total acquisition cost for a recycled material. We report work measurement studies conducted on the disassembly of 21 computers, 22 printers, and 32 monitors manufactured by 27 producers in the years from 1984 to 2001. Results include the weight per total separation time for each plastic part. Each recovered part is identified according to polymer resin using laser Raman spectroscopy by chemometric reference to a library of standards. We extrapolate time as well as the product input required to accumulate various specific types of plastic. We develop disassembly policies and show that they are effective for a variety of computer, printer, or monitor models, which is typical of the random product streams that arrive at electronics recycling facilities. The results demonstrate how new laser identification technology and work measurement can be used for plastics separation planning. [ABSTRACT FROM PUBLISHER]

Millions of end-of-life (EOL) electronic products represent more than one million tons of engineering thermoplastics. The economically and environmentally sound recovery of engineering thermoplastics from EOL electronics is a challenge to the sustainability of electronics manufacturing. In this paper, we review the technologies to separate and identify pure post-consumer plastics from EOL electronics, which are followed by the comparison of electronic plastics recycling processes and the network models for plastics recycling processes. We also review successful plastics recycling practices for electronics. In addition, further research directions for recycling plastics from EOL electronics are discussed. [ABSTRACT FROM PUBLISHER]