Revisiting the electron stimulated desorption of anions from thin films of CF2Cl2

Bass, A. D.; Arumainayagam, Christopher R.; Sanche, Léon

doi:10.1016/j.ijms.2008.05.030

Cited by 13 publications

(9 citation statements)

References 24 publications

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“…Previous condensed-phase methanol studies had only detected the electron-stimulated desorption of H − . 28 We attribute our observation of additional anion signals to the previously demonstrated superior sensitivity of the ToF mass analyzer 36,39 which probably derives from the use of a −2 kV pulse to inject desorbed anions into the time-of-flight tube. Figure 1 shows mass spectrometer signals as a function of incident electron energy.…”

Section: ■ Results and Discussionmentioning

confidence: 69%

Dynamics of Dissociative Electron–Molecule Interactions in Condensed Methanol

et al. 2014

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We have investigated the dynamics of low-energy (1−20 eV) electron-induced reactions in condensed thin films of methanol (CH 3 OH) through both electron-stimulated desorption (ESD) and postirradiation temperature-programmed desorption (TPD) experiments conducted under ultrahigh vacuum conditions. Results of ESD experiments, involving a high-sensitivity time-of-flight mass spectrometer, indicate that anion (H − , CH − , CH 2 − , CH 3 − , O − , OH − , and CH 3 O − ) desorption from the methanol thin film at incident electron energies below about 15 eV is dominated by processes initiated by the dissociation of temporary negative ions of methanol formed via electron capture, a resonant process known as dissociative electron attachment (DEA). However, postirradiation TPD investigation of radicals, especially •CH 2 OH and CH 3 O• remaining in the methanol thin film, demonstrates that electron impact excitation, not DEA, is the primary mechanism by which the radical−radical reaction products methoxymethanol (CH 3 OCH 2 OH) and ethylene glycol (HOCH 2 CH 2 OH) are formed. This apparent dichotomy between the results of ESD and postirradiation experiments is attributed to the low DEA cross section for methanol compared to that of species such as halomethanes. Our results suggest that for molecules such as methanol, low-energy electron-induced electronic excitation, rather than DEA, plays a dominant role in ionizing radiation-induced chemical synthesis in environments such as the interstellar medium. ■ INTRODUCTIONBecause of its simple chemical structure, methanol is a prototypical candidate for radiolysis studies of oxygencontaining biomolecules such as DNA. The radiation chemistry of methanol is of particular interest because methanol is exposed to different types of ionizing radiation in varying environments and phases. For example, liquid methanol is used as a solvent in radiation-induced grafting of copolymer composites. 1 The radiation chemistry of condensed methanol is also of astrochemical interest because methanol is found in relatively high abundance in protostar environments. Methanol is thought to be an important precursor in cosmic ices not only to species such as methyl formate (HCOOCH 3 ), ethylene glycol (HOCH 2 CH 2 OH), and dimethyl ether (CH 3 OCH 3 ) but also to many prebiotic species such as simple sugars and amino acids. 2−4 Because of such applications, the high-energy radiolysis of methanol has been extensively studied over a period spanning seven decades. 5−9 More recent advances, however, have demonstrated that studying the interactions of low-energy electrons with condensed matter is essential to obtaining a fundamental understanding of radiation chemistry because the interactions of high-energy radiation, such as cosmic rays (E max ∼ 10 20 eV), with matter produce large numbers of low-energy (<15 eV) secondary electrons, which are thought to initiate radiolysis reactions in the condensed phase. 10,11 In this publication, we investigate the chemistry induced in condensed methanol by such low-energ...

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Section: ■ Results and Discussionmentioning

confidence: 69%

Dynamics of Dissociative Electron–Molecule Interactions in Condensed Methanol

et al. 2014

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“…For a more detailed understanding of the mechanism of latent track formation in PADC, it may be possible to use the DD related O – desorption signal from DGMEA at 30 eV, and so probe such processes at electron energies below the threshold for anion desorption at ∼5 eV, for example via low lying shape resonances. A similar approach has been used to monitor damage in CF 2 Cl 2 and CH 3 COH. , Alternatively, changes in high-resolution-electron-energy-loss vibrational or electronic spectra may provide useful information . Finally, we note that the radical and ions created by the LEEs may undergo subsequent chemical reactions (e.g., in the case of water radiolysis see Marignier et al).…”

Section: Discussionmentioning

confidence: 91%

Elucidation of the Two-Step Damage Formation Process of Latent Tracks in Poly(allyl diglycol carbonate), PADC: Role of Secondary Low-Energy Electrons

et al. 2018

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“…Similar behaviours have been reported for anion yields from other electron-irradiated films and are related to the fact that the ESD signal derives essentially from the film-vacuum interface. 15,17 Fig. 1 Diagram showing the analysis chamber region of the electron stimulated desorption apparatus.…”

Section: Resultsmentioning

confidence: 99%

“…Measurements were performed at the University of Sherbrooke. Details of the techniques were given in previous papers, 1,14,15 a schematic diagram of the principal apparatus is shown in Fig. 1.…”

Section: Methodsmentioning

confidence: 99%

“…The yields and mass to charge (m/z) ratios of desorbed charged particles (alternately anions and cations) were measured by time of flight (ToF) analysis as described earlier. 14,15 The ToF technique requires that the electron beam be operated in a pulsed mode and typically the gun was pulsed 'on' for 800 ns at a rate of 5000 Hz. The time-averaged incident current for most of the present measurements was 4 nA, as measured on the clean Pt foil at an incident electron energy 'E i ' of 10 eV.…”

Section: Methodsmentioning

confidence: 99%

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Electron stimulated desorption of anions and cations from condensed allyl glycidyl ether

Yıldırım¹,

Balcan²,

Bass³

et al. 2010

Phys. Chem. Chem. Phys.

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We report measurements of the electron stimulated desorption (ESD) of anions and cations from thin films of allyl glycidyl ether (AGE), formed by condensation onto multilayer Kr and Pt substrates using a high sensitivity time of flight mass analyser. Measurements were performed as a function of film thickness, incident electron energy (E(i)) and effective incident current. Below incident electron energies of 20 eV the desorption of anions is dominated by the process of dissociative electron attachment (DEA) via several transient negative ions at E(i) between 5.5 and 16.5 eV. Comparisons between measurements for AGE and ethyl oxirane show that the ESD of anions is essentially that of the glycidyl (epoxide) ring, though DEA occurring at the ether, within the linear part of the AGE molecule is also observed. Cation yields are dominated by the desorption of small fragments formed via scission of the same ether bond.

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Revisiting the electron stimulated desorption of anions from thin films of CF2Cl2

Cited by 13 publications

References 24 publications

Dynamics of Dissociative Electron–Molecule Interactions in Condensed Methanol

Dynamics of Dissociative Electron–Molecule Interactions in Condensed Methanol

Elucidation of the Two-Step Damage Formation Process of Latent Tracks in Poly(allyl diglycol carbonate), PADC: Role of Secondary Low-Energy Electrons

Electron stimulated desorption of anions and cations from condensed allyl glycidyl ether

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