Welcome to DU! The truly grassroots left-of-center political community where regular people, not algorithms, drive the discussions and set the standards. Join the community: Create a free account Support DU (and get rid of ads!): Become a Star Member All Forums Issue Forums Culture Forums Alliance Forums Region Forums Support Forums Help & Search

OKIsItJustMe

(19,933 posts)
Fri Jan 13, 2012, 10:50 AM Jan 2012

Researchers discover particle which could ‘cool the planet’

http://www.manchester.ac.uk/aboutus/news/display/?id=7848
[font face=Times,Times New Roman,Serif][font size=5]Researchers discover particle which could ‘cool the planet’[/font]

13 Jan 2012

[font size=4]Scientists have shown that a new molecule in the earth’s atmosphere has the potential to play a significant role in off-setting global warming by cooling the planet.[/font]

[font size=3]In a breakthrough paper published in Science, researchers from The University of Manchester, The University of Bristol and Sandia National Laboratories report the potentially revolutionary effects of Criegee biradicals.

These invisible chemical intermediates are powerful oxidisers of pollutants such as nitrogen dioxide and sulfur dioxide, produced by combustion, and can naturally clean up the atmosphere.

Although these chemical intermediates were hypothesised in the 1950s, it is only now that they have been detected. Scientists now believe that, with further research, these species could play a major role in off-setting climate change.

…[/font][/font]
http://dx.doi.org/10.1126/science.1213229

https://share.sandia.gov/news/resources/news_releases/criegee_intermediates/
[font face=Times,Times New Roman,Serif]January 13, 2012
[font size=5]Sandia researchers, UK partners publish groundbreaking work on Criegee intermediates in Science magazine[/font]

[font size=3]LIVERMORE, Calif. — In a breakthrough paper published in this week’s issue of Science magazine, researchers from Sandia’s Combustion Research Facility, the University of Manchester and Bristol University report direct measurements of reactions of a gas-phase Criegee intermediate using photoionization mass spectrometry.


Criegee intermediates — carbonyl oxides — are implicated in autoignition chemistry and are pivotal atmospheric reactants, but only indirect knowledge of their reaction kinetics had previously been available. The article, titled Direct Kinetic Measurements of Criegee Intermediate (CH[font size=1]2[/font]OO) Formed by Reaction of CH[font size=1]2[/font]I with O[font size=1]2[/font], reports the first direct kinetics measurements made of reactions of any Criegee species, in this case formaldehyde oxide (CH[font size=1]2[/font]OO). These measurements determine rate coefficients with key species, such as sulfur dioxide (SO[font size=1]2[/font]) and nitrogen dioxide (NO[font size=1]2[/font]), and provide new insight into the reactivity of these transient molecules.

The detection and measurement of the Criegee intermediate reactions was made possible by a unique apparatus, designed by Sandia researchers, that uses light from a third-generation synchrotron user facility, Lawrence Berkeley National Laboratory’s Advanced Light Source, to investigate chemical reactions that are critical in hydrocarbon oxidation. The intense tunable light from the synchrotron allows researchers to discern the formation and removal of different isomeric species — molecules that contain the same atoms but are arranged in different combinations.

In the present case, CH[font size=1]2[/font]OO can be distinguished from its more stable isomer, formic acid (HCOOH), because of their differing thresholds for photoionization. The Manchester and Bristol researchers recognized that this apparatus could elucidate not only combustion reactions but also important tropospheric oxidation processes, such as ozonolysis.

…[/font][/font]
5 replies = new reply since forum marked as read
Highlight: NoneDon't highlight anything 5 newestHighlight 5 most recent replies
Researchers discover particle which could ‘cool the planet’ (Original Post) OKIsItJustMe Jan 2012 OP
Hmmm ... no mention of dioxirane ? eppur_se_muova Jan 2012 #1
Dioxirane is in the full article OKIsItJustMe Jan 2012 #2
Gee, I'm sure this won't have any unintended consequences NickB79 Jan 2012 #3
Let’s see… what are the consequences of doing nothing? OKIsItJustMe Jan 2012 #4
Unknown? joshcryer Jan 2012 #5

OKIsItJustMe

(19,933 posts)
2. Dioxirane is in the full article
Fri Jan 13, 2012, 02:40 PM
Jan 2012
[font face=Times, Serif][font size=3]…

In the present experiments, CH[font size=1]2[/font]I was produced by 248-nm photolysis of diiodomethane, CH[font size=1]2[/font]I[font size=1]2[/font], at 298 K and 4 torr, in a large excess of O[font size=1]2[/font]. The reacting mixture was interrogated by tunable synchrotron photoionization mass spectrometry. A time-resolved mass spectrum from the CH[font size=1]2[/font]I[font size=1]2[/font]/O[font size=1]2[/font] system is shown in Fig. 1. The resolution of the mass spectrometer is sufficient to establish that the nominal mass/charge (m/z) = 46 peak arises from CH[font size=1]2[/font]O[font size=1]2[/font] and not, for example, C[font size=1]2[/font]H[font size=1]6[/font]O (fig. S1). The formation rate of the m/z = 46 species is correlated with the disappearance rate of CH[font size=1]2[/font]I (m/z = 141) (figs. S2 to S4), establishing that CH[font size=1]2[/font]OO is a direct product from the reaction of CH[font size=1]2[/font]I with O[font size=1]2[/font]. Tuning the synchrotron photon energy allows a photoionization spectrum of the m/z = 46 species to be measured (Fig. 2). The photoionization spectrum agrees with that measured for CH[font size=1]2[/font]OO in chlorine-initiated DMSO oxidation (13) and with CCSD(T)/CBS (coupled-cluster with single and double excitations and perturbative treatment of triple excitations/complete basis set extrapolation) calculations for the CH[font size=1]2[/font]OO ionization energy (expected to be accurate to 0.05 eV) (16). Dioxirane and formic acid have much higher ionization energies, 10.82 eV and 11.33 eV (16, 17). The mass and the photoionization spectrum support unambiguous assignment of the product as formaldehyde oxide, CH[font size=1]2[/font]OO. A small formic acid signal is observed at longer times (fig. S5), which could be produced by reaction of the Criegee intermediate.



Addition of NO up to |NO| = 5 × 10[font size=1]15[/font] cm[font size=1]-3[/font] or H[font size=1]2[/font]O up to |H[font size=1]2[/font]O| = 3 × 10[font size=1]16[/font] cm[font size=1]-3[/font] produced no measurable increase in the decay rate of CH[font size=1]2[/font]OO (figs. S11 to S13). Reaction of NO with CH[font size=1]2[/font]OO is postulated to form CH[font size=1]2[/font]O and NO[font size=1]2[/font] (8); however, no product formation could be observed in these experiments. The reaction of CH[font size=1]2[/font]OO with water is thought to produce hydroxymethylhydroperoxide (HOCH[font size=1]2[/font]OOH, HMHP) by association (24) or to catalyze isomerization (25). The photon energy of the measurements, 10.5 eV, is well below the ionization energy of formic acid (17) and dioxirane (16) (Fig. 2), so the isomerization channel would still lead to a loss of photoionization signal at m/z = 46. The photoionization behavior of HMHP is unknown, but at the highest water concentrations a very faint product signal, much too small for kinetic analysis, can be observed at m/z = 64.

…[/font][/font]
Latest Discussions»Issue Forums»Environment & Energy»Researchers discover part...