A method is described of determining three-body conversion coefficients for the production of homonuclear diatomic ions. The technique involves ion sampling from the positive column of a dc discharge. For neon, values of the rate coefficient vary from 5.7-8.9 x IO"" 32 cm 6 /sec depending on the values of a number of experimental parameters. In argon values range from 3.0-4.7 x 10" 3 cm 6 /sec. The present results are compared with values obtained using other techniques.
the apparatus for the variable temperature measurements. J. R. Brews provided many answers to questions regarding radiative recombination. R. A. Logan and Mrs. H. V. Carlson made many suggestions useful in preparing the manuscript. We would especially like to thank T. N. Morgan for discussions and correspondence on the interpretation of his tunn'eIing analysis. One of us (D.J.S.) would like to thank M. DiDomenico for the opportunity to work on this problem during a summer at BTL.For studies of cataphoresis in He-Ne mixtures, an analytic expression is derived for the functional dependence of the neon atoms in the axial direction. The analysis, which involves the continuity equation, considers the production and loss mechanisms of the Ne+ ions. The present theory can be used to predict the degree of ionization of neon at a given pressure and current, when the appropriate rate coefficients are known. In addition, techniques for ion sampling from gaseous plasmas have been used in the present investigation. Measurements have been made in commercial helium-gas samples having a quoted neon concentration ::;0,001 % and in samples containing 0.05% neon. Studies were conducted over a pressure and current range of 7-30 Torr and 8-80 rnA, respectively. Depending on the experimental conditions, the following ions were observed: He2+, Ne+, Ne2+, and HeNe+. For the case of HeNe+, the present studies permit an estimate of the rate coefficient for the reaction Ne++2He->HeNe++He which is comparable to values obtained from afterglow studies. Measured values of the degree of ionization are in good agreement with values calculated using the present theory.
aGraphene is a wonder material possessing unique properties; however, graphene prepared by exfoliation of graphite has property to restack because of van der Waals interactions to form graphite. This restacking can be prevented by insertion of large molecules like fullerene, which not only exfoliates graphite layer but also prevents restacking of prepared graphene sheets. The present article also describes a mild method of graphite oxide synthesis (GO) for lower degree of oxidation resulting in less defected (ruptured carbon framework) graphene sheets. Exfoliation is performed by intercalation of large fullerene molecules by aqueous reaction of fullerene hydroxide (fullerenol) with the epoxy functionalities on graphite oxide to prepare fullerene intercalated graphite (G-Fol). Fullerene functionalization of GO to form G-Fol has been established by FTIR spectroscopy, UV-Vis spectroscopy, TGA and number of layers has been ascertained by Raman spectroscopy, XRD and HRTEM. Stable exfoliation of G-Fol has been confirmed by change in absorbance with time. Photoluminescence property of the material is also evaluated by fluorescence emission and excitation measurement at different excitation and emission wavelengths, respectively. The present article explains a new method of exfoliation of graphite to form stable functionalized graphene layers with fewer defects for future applications as buffer layer in electronic devices.
Ion-sampling measurements have been made from the positive column of dc discharges in mixtures of 0.05%, 0.10%, and 0.28% nitrogen in helium. The major ions observed were He+, He2+, N+, and N2+. Traces of Ne+, Ar+, N3+, N4+, O+, O2+, NO+, and N2O+ were also detected. The variation of N+ and N2+ with distance from the cathode was measured as a function of gas pressure and discharge current. Using the axial variations, estimates have been made of the average degree of ionization of nitrogen. Measurements using certain types of cathodes for various discharge conditions show the volume removal of nitrogen from the mixture due to processes occurring at the cathode. Conditions which produce the removal of nitrogen are discussed. Considerations for the purification of noble gases contaminated by small concentrations of nitrogen are also mentioned. The result emphasize the difficulty of conducting dc gas-discharge studies, on known small concentrations of a molecular gas such as nitrogen.
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