Glow discharge in rare-gas and metal vapour mixture

Conclusion The results are summarized in the form of graphs which illustrate the dependence of the rate coefficients on three parameters: E/N (electric field over total neutral concentration) x_e (ionization degree) and n₁ (relative concentration of cadmium). In such a way, we have tried to point out the main feature of the collisional rates under the conditions of steady-state, weakly ionized plasma. The use of the maxwellian distribution function for an evaluation of the rate coefficients would yield the results which differ substantially from ours. This concerns, particularly, the excitations from the ground state of atom efficacy of which depends on the high energy distribution tail. Since the true distribution function from Ref. [1] was employed in our calculations, it can be inferred that the main source of the inaccuracy in the rate coefficients is essentially given by the cross-sections used. It is believed that the present results can serve for a more quantitative understanding or for obtaining insight into the microscopic phenomena occurring in the positive column of the discharge.     

Calculation of the He-Cd dc discharge

Numerical evaluations of the excited atom densities and the volt-ampere characteristics in He-Cd dc mixture discharge in a cylindrical tube are reported. For this purpose, under non-equilibrium conditions in low current and low pressure discharge, a set of coupled rate equations for the number densities of atoms in most important quantum states is solved. A model of Cd-and He-atom possessing six and four levels, respectively, is assumed. The results of the computation are given as a function of the external positive column parameters at relative cadmium concentration 10^–3.     

Glow discharge in rare-gas and metal vapour mixture

Applying the Boltzmann equation to a He-Cd mixture discharge the electron energy distribution functions, kinetic coefficients and collision frequencies are numerically calculated. Calculations are made for a homogeneous and stationary discharge plasma subjected to an externally applied electric field. The collision processes which have been taken into account are elastic and inelastic collisions of electrons with He and Cd atoms as well as mutual encounters of electrons. In this case the electron energy distribution and all the quantities calculated from it are dependent on the reduced electric field, the ionization degree and the relative cadmium concentration.     

Solution of the Boltzmann equation for electrons in the discharges in metal vapour-helium mixtures

The Boltzmann equation was applied to the electron gas in the positive column in a helium-metal vapour mixture discharge. The problem was solved both numerically and approximately taking into account elastic and inelastic collisions of electrons with helium and metal atoms as well as mutual impacts of electrons. Separately the influence of Zn, Cd and Hg atoms on the mean kinetic energy, the mobility (drift velocity) and the diffusion of the electrons was investigated. Approximative relations for those quantities were found and a physical interpretation of their behaviour is given.     

Synthesis of biodegradable conjugated polymers with controlled backbone flexibility

A series of flexible, highly bright fluorescent poly(p‐phenyleneethynylene)s (PPEs) was prepared by employing a disulfide containing nonconjugated monomer at various ratios under Sonogashira reaction conditions. PPEs with flexible linkers exhibited fluorescence properties comparable to those of a fully conjugated PPE when less than 50% of flexible monomers were incorporated into the backbone. To evaluate the self‐assembly properties of PPEs, a series of conjugated polymer nanoparticles (CPNs) was fabricated by treating PPEs with organic acids followed by dialysis. CPNs containing linkers exhibited different complexation behavior with polysaccharides, warranting further investigation into how flexibility and biodegradability of CPNs influence their cellular interaction and entry. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1403–1412     

Distribution function of electrons and kinetic coefficients in cesium-argon mixture discharge

The distribution function of electrons in a cesium-argon mixture discharge is found in the present paper by solving Boltzmann's equation. The elastic and inelastic electron-atom collisions and electron-electron collisions are taken into consideration.The influence of the addition of cesium vapours to argon on the quantities characterizing the discharge plasma is explained. From the electron distribution function are calculated: the drift velocity, the mean energy, the ratio of the diffusion and mobility coefficients and the electron energy losses for individual elementary processes as functions of the electric field and the concentration of the neutral gas components.