High-resolution determination of the electron affinity of fluorine and bromine using crossed ion and laser beams

Blondel, Christophe; Cacciani, P.; Delsart, C.; Trainham, R.

doi:10.1103/physreva.40.3698

Cited by 269 publications

(154 citation statements)

References 18 publications

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“…The two experiments were performed under identical single collision conditions (collision cell argon gas pressure: 0.1 Ϫ 0.2 mTorr) with low collision energies adjusted to nearly identical values (2 eV) in the center-of-mass frame of reference (E com ). From the decomposition patterns it can be concluded that: (1) The gas phase basicity of F Ϫ (1530 kJ/mol) [35,36] Particularities of the three-dimensional structure of the anionic adduct could also contribute to the stability of an adduct in the gas phase. Computer modeling is a good approach to visualize and evaluate the interaction between a neutral analyte and the attaching anion.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of the role of multiple hydrogen bonding in offering stability to negative ion adducts in electrospray mass spectrometry

Cai

Concha

Murray

et al. 2002

J. Am. Soc. Mass Spectrom.

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An experimental approach, electrospray mass spectrometry (ES-MS), and a theoretical approach employing computer modeling, have been used to characterize the interaction between small inorganic anions and neutral analyte molecules that form anionic adduct species in negative mode ES mass spectrometry. Certain anionic adducts of small saccharides (e.g., ␣-D-glucose, sucrose) have shown exceptional stability in ES mass spectra even when internal energies are raised at high "cone" voltages. Computer modeling studies reveal that multiple hydrogen bonding strengthens the interaction between these neutral molecules and the attaching anion. The equilibrium structures and stabilization energies of these anionic adducts have been evaluated by semi-empirical, ab initio, and density functional theory (DFT) methods. Chloride anion is found to be capable of forming "bridging" hydrogen bonds between monosaccharide rings of polysaccharides resulting in the stabilization of chloride adducts, thus reducing the tendency for the glycosidic bond to decompose. Moreover, the tendency for various hydroxyl hydrogens on saccharide molecules to dissociate in the form of HA ( [5][6][7][8], have been used to generate anionic adducts for ES-MS studies. The formation and decomposition of chloride adducts have been further investigated from a thermodynamic standpoint [9 -12]. However, the conditions that favor the formation and survival of anionic adducts have not been extensively defined and are not fully understood. Moreover, the interactions between neutral analyte molecules and the attaching small inorganic anions have not been fully characterized.Various mass spectrometry methods have been applied to probe the interactions between ions and neutral analyte molecules [13][14][15]. These methods typically evaluate enthalpies of ion-molecule reactions or unimolecular dissociations of ionic adducts to derive gasphase thermodynamic properties such as bond energies and ion affinities. In some cases, the nature of the ion-molecule interaction could be further elucidated by determining the difference in the entropy changes for competing decomposition pathways [16,17]. To date, the vast majority of ion-molecule interaction studies performed by mass spectrometry focus on positive ion studies of cationic adduct species, especially protonated molecules [14] and alkali metal adducts [18 -21]. Dication adduct species, such as alkaline earth metal [22] and transition metal [23] adducts of oligosaccharides have also been explored. Small inorganic anions attaching to neutral analyte molecules, on the other hand, have received far less research attention. However, a few studies employing anion attachment in negative ion ES-MS have appeared, such as reports on iodide attachment to acetone [24], chloride attachment to saccharides [1, 10 -12], and cyanide attachment (including covalent) to fullerenes [6,8]. In order to gain insight into the exact nature of the interactions between neutral analyte molecules and attaching small inorganic anions that are responsi...

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Section: Resultsmentioning

confidence: 99%

Evaluation of the role of multiple hydrogen bonding in offering stability to negative ion adducts in electrospray mass spectrometry

Cai

Concha

Murray

et al. 2002

J. Am. Soc. Mass Spectrom.

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“…However, the threshold for this process is approximately 1.8 eV lower in CF, reflecting the difference between the electron affinities of F (∼3.40 eV [27]) and O (∼1.46 eV [28]). It is interesting to note that the binding energies of CF and NO are very similar, while those of the corresponding 3 Σ − anions reflect the difference between the respective electron affinities.…”

Section: A Neutral and Anion Potential Curvesmentioning

confidence: 98%

Resonant electron-CFcollision processes

2005

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Electronic structure methods are combined with variational fixed-nuclei electron scattering calculations and nuclear dynamics studies to characterize resonant vibrational excitation and electron attachment processes in collisions between low-energy electrons and CF radicals. Several low-lying negative ion states are found which give rise to strong vibrational excitation and which are expected to dominate the low-energy electron scattering cross sections. We have also studied several processes which could lead to production of negative ions (F − and C − ), however, in contrast to other recent predictions, we do not find CF in its ground state to be a significant source of negative ion production when interacting with thermal electrons.

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“…The C-C bond between C 7 F 15 and COOH is the weakest bond in the PFOA chemical structure because the fluorine atom has the strongest inductive electron withdrawal ability (Blondel et al, 1989). The light irradiation initially cleaves this weakest bond, which initiates the PFOA degradation.…”

Section: Mechanism Of Pfoa Degradationmentioning

confidence: 99%

Temperature effect on photolysis decomposing of perfluorooctanoic acid

Zhang

Pan

Zhou

2016

Journal of Environmental Sciences

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Perfluorooctanoic acid (PFOA) is recalcitrant to degrade and mineralize. Here, the effect of temperature on the photolytic decomposition of PFOA was investigated. The decomposition of PFOA was enhanced from 34% to 99% in 60 min of exposure when the temperature was increased from 25 to 85°C under UV light (201-600 nm). The limited degree of decomposition at 25°C was due to low quantum yield, which was increased by a factor of 12 at 85°C.Under the imposed conditions, the defluorination ratio increased from 8% at 25°C to 50% at 85°C in 60 min. Production of perfluorinated carboxylic acids (PFCAs, C7-C5), PFCAs (C4-C3) and TFA (trifluoroacetic acid, C2) accelerated and attained a maximum within 30 to 90 min at 85°C. However, these reactions did not occur at 25°C despite extended irradiation to 180 min. PFOA was decomposed in a step-wise process by surrendering one CF 2 unit. In each cyclical process, increased temperature enhanced the quantum yields of irradiation and reactions between water molecules and intermediates radicals. The energy consumption for removing each μmol of PFOA was reduced from 82.5 kJ at 25°C to 10.9 kJ at 85°C using photolysis. Photolysis coupled with heat achieved high rates of PFOA degradation and defluorination.

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High-resolution determination of the electron affinity of fluorine and bromine using crossed ion and laser beams

Cited by 269 publications

References 18 publications

Evaluation of the role of multiple hydrogen bonding in offering stability to negative ion adducts in electrospray mass spectrometry

Evaluation of the role of multiple hydrogen bonding in offering stability to negative ion adducts in electrospray mass spectrometry

Resonant electron-CFcollision processes

Temperature effect on photolysis decomposing of perfluorooctanoic acid

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