Search results for "Halogens"
showing 4 items of 24 documents
Plume chemistry and potential impacts of the plume from the recent activity at Halema’uma’u, Kilauea, USA.
2009
Since the 19 March 2008 explosion within Halema‘uma‘u that formed the new vent at Kilauea’s summit, degassing rates have been greatly elevated above the levels typical of previous years. The location and subsequent dispersion of this new degassing presents its own specific problems compared to that in the east rift zone. For example, throughout 2008 the Halema’uma’u plume was generally blown through the Kau desert, directly affecting downwind communities. In this study we present measurements made in July and halogens (HF, HCl, HBr and HI) in the new 2008. We characterize the gas chemistry in terms of SO 2 plume from Halema’uma’u in order to compare them with other plumes worldwide, includi…
Reactivity of 4-Aminopyridine with Halogens and Interhalogens : Weak Interactions Supported Networks of 4-Aminopyridine and 4-Aminopyridinium
2019
The reaction of 4-aminopyridine (4-AP) with ICl in a 1:1 molar ratio in CH2Cl2 produced the expected charge-transfer complex [4-NH2-1λ4-C5H4N-1-ICl] (1·ICl) and the ionic species [(4-NH2-1λ4-C5H4N)2-1μ-I+][Cl–] (2·Cl–) in a 2:1 relation, as indicated by 1H NMR spectroscopy in solution. In contrast, only the ionic compound [(4-NH2-1λ4-C5H4N)2-1μ-I+][IBr2–] (2·IBr2–) was observed in the analogous reaction with IBr. The reaction between 4-AP and I2 in a 1:1 molar ratio also afforded two components, one of which was identified as the congeneric cation in [(4-NH2-1λ4-C5H4N)2-1μ-I+][I7–] (2·I7–) that contains a polyiodide anion as a result of transformation in a 1:2 molar ratio between the starti…
Four-Component Relativistic DFT Calculations of C-13 Chemical Shifts of Halogenated Natural Substances
2015
We have calculated the (13) C NMR chemical shifts of a large ensemble of halogenated organic molecules (81 molecules for a total of 250 experimental (13) C NMR data at four different levels of theory), ranging from small rigid organic compounds, used to benchmark the performance of various levels of theory, to natural substances of marine origin with conformational degrees of freedom. Carbon atoms bonded to heavy halogen atoms, particularly bromine and iodine, are known to be rather challenging when it comes to the prediction of their chemical shifts by quantum methods, due to relativistic effects. In this paper, we have applied the state-of-the-art four-component relativistic density funct…
High-spectral-resolution Fabry-Pérot interferometers overcome fundamental limitations of present volcanic gas remote sensing techniques
2023
Remote sensing (RS) of volcanic gases has become a central tool for studying volcanic activity. For instance, ultraviolet (UV) skylight spectroscopy with grating spectrographs (GS) enables SO2 (and, under favourable conditions, BrO) quantification in volcanic plumes from autonomous platforms at safe distances. These measurements can serve volcanic monitoring and they cover all stages of volcanic activity in long measurement time series, which substantially contributes to the refinement of theories on volcanic degassing. Infrared (IR) remote sensing techniques are able to measure further volcanic gases (e.g., HF, HCl, CO2, CO). However, the employed Fourier transform spectrometers (FTSs) are…