QDB: A new database of plasma chemistries and reactions

One of the most challenging and recurring problems when modeling plasmas is the lack of data on the key atomic and molecular reactions that drive plasma processes. Even when there are data for some reactions, complete and validated datasets of chemistries are rarely available. This hinders research on plasma processes and curbs development of industrial applications. The QDB project aims to address this problem by providing a platform for provision, exchange, and validation of chemistry datasets. A new data model developed for QDB is presented. QDB collates published data on both electron scattering and heavy-particle reactions. These data are formed into reaction sets, which are then validated against experimental data where possible. This process produces both complete chemistry sets and identifies key reactions that are currently unreported in the literature. Gaps in the datasets can be filled using established theoretical methods. Initial validated chemistry sets for SF 6 /CF 4 /O 2 and SF 6 /CF 4 /N 2 /H 2 are presented as examples

MULTIPLE REFLECTION TIME DOMAIN METHOD IN DIELECTRIC-SPECTROSCOPY - APPLICATION TO STUDY OF SOME NORMAL PRIMARY ALCOHOLS

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STUDY OF DIELECTRIC-RELAXATION SPECTRA OF EPSILON AMINOCAPROIC ACID IN AQUEOUS-SOLUTION

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STUDY OF DIELECTRIC-RELAXATION SPECTRA OF EPSILON AMINOCAPROIC ACID IN AQUEOUS-SOLUTION

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State-selected dissociation of dehydrovincamine alkaloid stereo-isomers

International audienceWe have obtained results on alkaloid stereoisomers that show strongly stereoselective fragmentation processes. An original technique for such molecules, i.e. photoionisation by synchrotron radiation in the VUV range coupled to the photoelectron–photoion coincidence technique, is used to prepare state-selected parent ions with a very wide internal energy range. Mass spectra obtained after photoionisation, and metastable spectra obtained after electron impact ionisation, exhibit stereospecific fragmentations leading either to water loss and subsequent fragmentations in dehydrovincamine, or to carbomethoxy and ethyl loss in epi-dehydrovincamine. The results are in agreement with previous measurements obtained on the protonated samples, or on the similar vincamine molecule. Appearance energies for major fragmentations were recorded as well as a state-selected breakdown diagram for the epi-dehydrovincamine sample. They show that thresholds for the fragmentation processes are almost identical in the two isomers, indicating very similar thermodynamics. Very slow fragmentation decay for the first dissociation channels leads to the coexistence of parent and fragment ions in a very wide internal energy range of the breakdown diagram. The results show that the fragmentation of the system is most probably driven by strong steric factors. Further modelling with statistical theories should give the precise transition states and lead to a better understanding of this stereospecificity

Structural Analysis of Titan's Tholins by Ultra-High Resolution Mass Spectrometry

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Structural Analysis of Titan's Tholins by Ultra-High Resolution Mass Spectrometry

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Photoionisation and ion-molecule reaction studies involving radical species of planetary interest

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