Search results for "Argon"

Study of Inductive Coupled Hydrogen and Argon Plasma Interaction with SiO2 Glass

2009

This work is devoted to the diagnostics of interaction between hydrogen and argon with the surface of SiO2 glass walls. For diagnostics of the interaction, special high-frequency electrodeless light sources were prepared, filled with pure argon of 1 Torr or argon-hydrogen of total pressure of 1 Torr (Ar/H2 mixing ratio is 9:1). Besides the mostly used spherical and cylindrical lamps, dumbbell type lamps have also been investigated. The spectroscopic and AFM measurements showed that in comparison with pure argon plasma, the argon-hydrogen plasma causes non-uniform changes of the SiO2 surface. For these modifications active OH are primarily responsible molecules, created in the reactions of h…

Rotation of methyl radicals in a solid krypton matrix

2009

Electron spin resonance (ESR) measurements were carried out to study the rotation of methyl radicals (CH(3)) in a solid krypton matrix at 17-31 K temperature range. The radicals were produced by dissociating methane by plasma bursts generated by a focused 193 nm excimer laser radiation during the krypton gas condensation on the substrate. The ESR spectrum exhibits only isotropic features at the temperature range examined, and the intensity ratio between the symmetric (A) and antisymmetric (E) spin state lines exhibits weaker temperature dependence than in a solid argon matrix. However, the general appearance of the methyl radical spectrum depends strongly on temperature due to the pronounce…

Chemisorption of hydrogen on a V5+ cluster

1996

Abstract The binding between V 5 + and hydrogen is studied by collision induced dissociation of the cluster-adsorbate V 5 + H 2 . Vanadium clusters are produced by laser vaporization and injected into an electromagnetic ion trap. After mass separation of V 5 + , the pulsed addition of hydrogen yields V 5 + H 2 . The desorption of hydrogen is studied by acceleration of V 5 + H 2 with variable rf voltages and collisions with argon atoms. From the threshold voltage necessary for dissociation a binding energy of H 2 on V 5 + of 2.4 ± 0.3 eV is estimated. This value is consistent with a dissociative chemisorption of hydrogen.

Cure kinetics of a cobalt catalysed dicyanate ester monomer in air and argon atmospheres from DSC data

2004

A kinetic analysis of the cyclotrimerisation reaction of a dicyanate ester monomer catalysed by cobalt(II) acetylacetonate and nonylphenol in air and argon atmospheres has been carried out by differential scanning calorimetry (DSC). Dynamic and isothermal DSC scans as well as the glass transition temperature are the experimental data obtained. From isothermal scans a higher cyanate conversion in air than in argon was obtained. The cyanate conversions are satisfactorily described with a second-order kinetic equation in the kinetically controlled region, and by m-order (m<1) equation after vitrification is reached. Activation energies determined by different procedures agree among them, showi…

A new approach to the growth of ZnO by vapour transport

2005

The crystal growth of ZnO by vapour transport is classically made in presence of additional species which enhance the growth process. Usually, additional species have been considered as chemical transport agents that promote a typical CVT (Chemical Vapour Transport) process. Recently, we have proposed a new interpretation of the chemical role of some of these species. This new interpretation considers that, in some cases, the additional species promote a partial consumption of the O2 provided by the ZnO decomposition and, consequently, a Zn excess is generated. This excess of Zn pressure activates the ZnO decomposition and the growth rate is enhanced. Among those species, carbon shows an ad…

Argon broadening of the 13CO R(0) and R(7) transitions in the fundamental band at temperatures between 80 and 297K: comparison between experiment and…

2003

We present measurements of Ar-broadening parameters for the R(0) and R(7) lines in the fundamental band of13CO at eight temperatures from 80 to 297 K. The broadening parameters are determined by simultaneous least-squares fitting of spectra recorded using a frequency stabilized diode laser spectrometer. The comparison of the broadening parameter values for R(7) derived at room temperature and different pressures from different line profiles shows that an empirical line profile, which takes into account narrowing effects (Dicke narrowing and absorber speed dependence) but neglects any correlation between collisions, is able to describe the observed lines with constant values of the narrowing…

Solid-State Synthesis of “Bamboo-Like” and Straight Carbon Nanotubes by Thermolysis of Hexa-peri-hexabenzocoronene–Cobalt Complexes

2006

ChemInform Abstract: Convenient and Optimized Procedure for the Syntheses of Di- and Trialkoxycarbenium Tetrafluoroborates.

1990

Abstract A convenient and optimized procedure for the synthesis of some diand trialkoxycarbenium tetrafluoroborates under an argon atmosphere and using a specially developed apparatus is described.

Convenient and Optimized Procedure for the Syntheses of Di- and Trialkoxycarbenium Tetrafluoroborates

1989

Abstract A convenient and optimized procedure for the synthesis of some diand trialkoxycarbenium tetrafluoroborates under an argon atmosphere and using a specially developed apparatus is described.

Inelastische Lichtstreuung von Cellulosenitratlösungen

1974

Es wird ein Homodyngerat zur Messung der inelastischen Lichtstreuung beschrieben, das mit einem Argon-Ionenlaser ausgerustet ist und mit einem Autokorrelator arbeitet. Das Gerat wird benutzt, um das Verhalten der Fadenmolekule von Cellulosenitrat in verdunnter Losung zu untersuchen. Mit dieser Technik wird es moglich, sogar fur unabgebaute native Cellulose die Diffusionskoeffizienten der Translation D zu bestimmen, die ein sehr niedriges D (<10−7 cm2 s−1) aufweisen und bisher nur naherungsweise bekannt waren, da die konventionellen Mestechniken der optischen Beobachtung eines Konzentrationsausgleiches dann recht ungenau werden. A homodyne light beat spectrometer equipped with an argon ion l…