Valence electronic structure and photofragmentation of 1,1,1,2-tetrafluoroethane (CF<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>3</mml:mn></mml:msub></mml:math>-CH<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>F)

Kettunen, Johannes; Sankari, Anna; Partanen, L.; Urpelainen, Samuli; Kivimaeki, A.; Huttula, Marko

doi:10.1103/physreva.85.062703

Cited by 11 publications

(6 citation statements)

References 48 publications

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“…The coincidence logic follows the schemes utilized earlier 17,39,[41][42][43][44][45] , where the electron detection from the HDA sends a signal to the pulsed voltage source (Directed Energy Inc. model PVX-4450) which raises the voltages in the extraction region for a specified time interval, allowing the measurement of the ion flight times. Due to the inherent di↵erences between the transmissions of the HDA and the TOFMS, there exists a high likelyhood of producing false coincidences between electrons and ions that in reality have no correlation.…”

Section: Methodsmentioning

confidence: 99%

Role of ultrafast dissociation in the fragmentation of chlorinated methanes

Kokkonen

Jänkälä

Patanen

et al. 2018

The Journal of Chemical Physics

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Photon-induced fragmentation of a full set of chlorinated methanes (CH3Cl, CH2Cl2, CHCl3, CCl4) has been investigated both experimentally and computationally. Using synchrotron radiation and electron-ion coincidence measurements, the dissociation processes were studied after chlorine 2p electron excitation. Experimental evidence for CH3Cl and CH2Cl2 contains unique features suggesting that fast dissociation processes take place. By contrast, CHCl3 and CCl4 molecules do not contain the same features, hinting that they experience alternative mechanisms for dissociation and charge migration. Computational work indicates differing rates of charge movement after the core-excitation, which can be used to explain the differences observed experimentally.

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Section: Methodsmentioning

confidence: 99%

Role of ultrafast dissociation in the fragmentation of chlorinated methanes

Kokkonen

Jänkälä

Patanen

et al. 2018

The Journal of Chemical Physics

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“…However, some of the detected ions can only be generated through rearrangement reactions. A notable example is CHF 2 + , [4][5][6][7][8] which is commonly observed in these experiments and cannot be formed via direct fragmentation of ionized CF 3 CH 2 F. Interestingly, this rearrangement product ion is very often reported as the fourth most intense in mass spectra. 6 Following the investigation of Zhou et al, 4 the detection of CHF 2…”

Section: Introductionmentioning

confidence: 78%

“…Introduced to replace R-12 (dichlorodifluoromethane, CCl 2 F 2 ), it has become the most abundant hydrofluorocarbon (HFC) in the atmosphere, as reported by Harrison et al 1 Since the beginning of its commercial usage, CF 3 CH 2 F has been the subject of numerous experimental studies concerning the effects of ionizing radiation. [2][3][4][5][6][7][8][9][10][11] With a few exceptions, 10,11 most of them focused on valence ionization (more details on other CF 3 CH 2 F irradiation experiments are given elsewhere 11 ). In the realm of computational studies centered on R-134a, a substantial body of research has also emerged, [12][13][14][15][16][17] the most recent of which is by our group.…”

Section: Introductionmentioning

confidence: 99%

Deciphering the irradiation induced fragmentation–rearrangement mechanisms in valence ionized CF3CH2F

Bonfim,

Souza,

de Oliveira

et al. 2024

The Journal of Chemical Physics

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The increasing presence of 1,1,1,2-tetrafluoroethane (CF3CH2F) in the atmosphere has prompted detailed studies into its complex photodissociation behavior. Experiments focusing on CF3CH2F irradiation have unveiled an array of ions, with the persistent observation of the rearrangement product CHF2+ not yet fully understood. In this work, we combine density functional theory, coupled-cluster calculations with a complete basis set formalism, and atom-centered density matrix propagation molecular dynamics to investigate the energetics and dynamics of different potential pathways leading to CHF2+. We found that the two-body dissociation pathway involving an HF rearrangement, which was previously considered complex for CHF2+ formation, is actually straightforward but not likely due to the facile loss of HF. In contrast, our calculations reveal that the H elimination pathway, once thought of as a potential route to CHF2+, is not only comparably disadvantageous from both thermodynamic and kinetic points of view but also does not align with experimental data, particularly the lack of a rebound peak at m/z 101–102. We establish that the formation of CHF2+ is predominantly via the HF elimination channel, a conclusion experimentally corroborated by studies involving the trifluoroethylene cation CF2CHF+, a key intermediate in this process.

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“…In the case of SUVA, an inner valence structure is observed to increase after a binding energy of 30 eV with a maximum around 40 eV. 29 Although we are mainly interested in valence photoionization, our data are extended up to 320 eV, going beyond the carbon K shell. At the C 1 s edge the double-to-total ratio presents a step increase as a function of the photon energy because of Auger effects.…”

Section: Resultsmentioning

confidence: 98%

Double‐valence photoionization of SUVA134a molecule (CFH₂CF₃)

Morcelle

Medina

Ribeiro

et al. 2021

Rapid Comm Mass Spectrometry

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In this work we investigate the single-photon double ionization of the SUVA 134a (1,1,1,2-tetrafluoroethane) molecule in the energy range from 21.21 to 320 eV. Our experimental data are supported by Thomas' and Samson's models. It is shown that the double photoionization of the SUVA 134a can be expressed as a sum of the so-called shake-off (SO) and the knockout (KO) processes. Methods:The experiments were executed at the TGM beamline at Laborat orio Nacional de Luz Síncrotron in Campinas, Brazil. The source of EUV and X-ray radiation was a bending magnet that enabled us to work in the photon energy range of 21.21 to 320 eV. The spectrometer was devised to collect 100% of the ions with kinetic energies up to 30 eV. The photoelectron-photoion (PEPICO) and photoelectron-photoion-photoion (PE2PICO) coincidence techniques were used in the present work. Results:The ratio of double-to-total photoionization as a function of the photon energy for the SUVA molecule exhibits remarkably similar behavior with other atomic and molecular systems. SO depends on large excess energy above the ionization threshold, enabling the photoelectron to leave the interaction region rather speedily to yield a sudden change in the Coulomb field that the shaken electron feels. The measured asymptotic SO probability is P SO (∞) = 0.09. Conclusions:The present analysis shows that the separation of SO and KO processes relies on the experimental evidence that there is no significant interference between SO and KO. The analysis also shows that the separate formulation of KO and SO presents a factual portrayal of double photoionization.Despite having 50 electrons, SUVA has lower double-to-total photoionization fraction (9%) in comparison, for instance, to argon atoms ($20%), which has 18 electrons. This lower e-e correlation could be attributed to its larger volume, that is, lower electron density. | INTRODUCTIONAt low photon energies (EUV), photo-double ionization of atoms and molecules is a rare event, corresponding to only a small percentage when compared to single ionization. It can take place either directly or indirectly. Photo-double ionization of atoms and molecules by a single photon is a central many-body process. Direct double ionization is portrayed by a single photon absorption by the target followed by the sudden ejection of two electrons, as opposed to sequential or indirect core ionization or excitation followed by a series of Auger decays, or

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Valence electronic structure and photofragmentation of 1,1,1,2-tetrafluoroethane (CF3-CH2F)

Cited by 11 publications

References 48 publications

Role of ultrafast dissociation in the fragmentation of chlorinated methanes

Role of ultrafast dissociation in the fragmentation of chlorinated methanes

Deciphering the irradiation induced fragmentation–rearrangement mechanisms in valence ionized CF3CH2F

Double‐valence photoionization of SUVA134a molecule (CFH₂CF₃)

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Valence electronic structure and photofragmentation of 1,1,1,2-tetrafluoroethane (CF3-CH2F)

Cited by 11 publications

References 48 publications

Role of ultrafast dissociation in the fragmentation of chlorinated methanes

Role of ultrafast dissociation in the fragmentation of chlorinated methanes

Deciphering the irradiation induced fragmentation–rearrangement mechanisms in valence ionized CF3CH2F

Double‐valence photoionization of SUVA134a molecule (CFH2CF3)

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Double‐valence photoionization of SUVA134a molecule (CFH₂CF₃)