Topic
Autoionization
About: Autoionization is a research topic. Over the lifetime, 4098 publications have been published within this topic receiving 78866 citations.
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TL;DR: Experimental evidence is presented that the threshold pressure of ~120 GPa induces in molecular ammonia the process of autoionization to yet experimentally unknown ionic compound--ammonium amide, opening new possibilities for studying molecular interactions in hydrogen-bonded systems.
Abstract: Ionization of highly compressed ammonia has previously been predicted by computation. Here, the authors provide experimental evidence for this autoionization process at high pressures, showing the transformation of molecular ammonia into ammonium amide.
3,638 citations
TL;DR: In this article, the authors proposed a model in which the time dependence of the photoluminescence intensity of a single nanosize quantum dot under cw excitation conditions shows a sequence of ''on'' and ''off'' periods similar to a random telegraph signal.
Abstract: We propose a model in which the time dependence of the photoluminescence intensity of a single nanosize quantum dot under cw excitation conditions shows a sequence of ``on'' and ``off'' periods similar to a random telegraph signal. In our model the off periods are the times when the dot is ionized and the luminescence is quenched by nonradiative Auger recombination. The duration of the on periods depends on the ionization rate of the dot via thermal or Auger autoionization, and depends strongly on excitation intensity. Numerical simulations reproduce the random intermittency recently observed in the photoluminescence intensity of a single CdSe quantum dot.
743 citations
TL;DR: The autoionization mechanism is revealed by sampling and analyzing ab initio molecular dynamics trajectories and the rare fluctuations in solvation energies that destabilize an oxygen-hydrogen bond are identified.
Abstract: The dissociation of a water molecule in liquid water is the fundamental event in acid-base chemistry, determining the pH of water. Because of the short time scales and microscopic length scales involved, the dynamics of this autoionization have not been directly probed by experiment. Here, the autoionization mechanism is revealed by sampling and analyzing ab initio molecular dynamics trajectories. We identify the rare fluctuations in solvation energies that destabilize an oxygen-hydrogen bond. Through the transfer of protons along a hydrogen bond "wire," the nascent ions separate by three or more neighbors. If the hydrogen bond wire connecting the two ions is subsequently broken, a metastable charge-separated state is visited. The ions may then diffuse to large separations. If, however, the hydrogen bond wire remains unbroken, the ions recombine rapidly. Because of their concomitant large electric fields, the transient ionic species produced in this case may provide an experimentally detectable signal of the dynamics we report.
676 citations
TL;DR: In this article, the authors presented new calculations of ionization equilibrium fractions of 11 abundant elements (C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni) as functions of temperature.
Abstract: The paper presents new calculations of ionization equilibrium fractions of 11 abundant elements (C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni) as functions of temperature. Convenient coefficients for fitting the rates of collisional ionization, radiative recombination, and dielectronic recombination are also tabulated. Many of the ionization rates are based on recent experimental measurements of cross sections for collisional ionization and autoionization following inner-shell excitation. These rates are used elsewhere in computations of nonequilibrium ionization, radiative cooling, radiative shock models, and plasma emission diagnostics.
457 citations
TL;DR: In this article, the wavelengths, radiative transition probabilities, and autoionization rates for ions with atomic numbers Z = 4 to 34 have been calculated for ion types with atomic number Z = 34.
375 citations