Weak Acids Enhance Halogen Activation on Atmospheric Water’s Surfaces

We report that rates of I_2(g) emissions, measured via cavity ring-down spectroscopy, during the heterogeneous ozonation of interfacial iodide: I^–(surface, s) + O_3(g) + H+(s) →→ I_2(g), are enhanced several-fold, whereas those of IO·(g) are unaffected, by the presence of undissociated alkanoic acids on water. The amphiphilic weak carboxylic acids appear to promote I_2(g) emissions by supplying the requisite interfacial protons H^+(s) more efficiently than water itself, at pH values representative of submicrometer marine aerosol particles. We infer that the organic acids coating aerosol particles ejected from ocean’s topmost films should enhance I_2(g) production in marine boundary layers

Heterogeneous Reaction of Gaseous Ozone with Aqueous Iodide in the Presence of Aqueous Organic Species

The fast reaction of gaseous ozone, O_3(g), with aqueous iodide, I−(aq), was found to be affected by environmentally relevant cosolutes in experiments using cavity ring-down spectroscopy (CRDS) and electrospray ionization mass spectrometry (ESIMS) for the detection of gaseous and interfacial products, respectively. Iodine, I_2(g), and iodine monoxide radical, IO(g), product yields were suppressed in the presence of a few millimolar phenol (pK_a = 10.0), p-methoxyphenol (10.2), or p-cresol (10.3) at pH ≥ 3 but unaffected by salicylic acid (pK_(a2) = 13.6), tert-butanol, n-butanol, or malonic acid. We infer that reactive anionic phenolates inhibit I_2(g) and IO(g) emissions by competing with I−(aq) for O_3(g) at the air/water interface. ESIMS product analysis supports this mechanism. Atmospheric implications are discusse

1/fα1/f^\alpha spectra in elementary cellular automata and fractal signals

We systematically compute the power spectra of the one-dimensional elementary cellular automata introduced by Wolfram. On the one hand our analysis reveals that one automaton displays $1/f$ spectra though considered as trivial, and on the other hand that various automata classified as chaotic/complex display no $1/f$ spectra. We model the results generalizing the recently investigated Sierpinski signal to a class of fractal signals that are tailored to produce $1/f^{\alpha}$ spectra. From the widespread occurrence of (elementary) cellular automata patterns in chemistry, physics and computer sciences, there are various candidates to show spectra similar to our results.Comment: 4 pages (3 figs included

Statistical Communication Theory

Contains reports on four research projects

Statistical Communication Theory

Contains reports on four research projects

Statistical Communication Theory

Contains research objectives and reports on four research projects

Statistical Communication Theory

Contains reports on two research projects

Sierpinski signal generates 1/fα1/f^\alpha spectra

We investigate the row sum of the binary pattern generated by the Sierpinski automaton: Interpreted as a time series we calculate the power spectrum of this Sierpinski signal analytically and obtain a unique rugged fine structure with underlying power law decay with an exponent of approximately 1.15. Despite the simplicity of the model, it can serve as a model for $1/f^\alpha$ spectra in a certain class of experimental and natural systems like catalytic reactions and mollusc patterns.Comment: 4 pages (4 figs included). Accepted for publication in Physical Review

Statistical Communication Theory

Contains reports on seven research projects