Radical trapping in a mass spectrometer ion source. 1

McEwen, Charles N.; Rudat, M. A.

doi:10.1021/ja00405a009

Cited by 57 publications

(29 citation statements)

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“…We propose instead that the process responsible for the observed fragmentation is indeed the n-propyl to isopropyl isomerization whose rate in the ion cluster has been determined from the slope of the fitted line shown in Fig. 2 to be approximately (15 ^s)~' in accordance with a number of isomerization studies of gas phase hydrocarbon ions [14][15][16].…”

Section: Ii) An Analogous Process Of Metastable Decomposition With Thsupporting

confidence: 81%

“…Conflicting postulations have been made with respect to the isomerization rates of the various propyl isomers. According to Mc Ewen and Rudat [14], a large number of available gas phase data suggest that conversion of the c-propyl to the ^cc-propyl isomer is fast (~10~^ s [15]) but isomerization of w-propyl to sec'propyl is relatively much slower [16]. It should be mentioned, however, that recent gas phase radiolytic results on alkylation of benzene by propyl ions are consistent with the requirement of a fast rate for the rearrangement of ^-propyl ions and a much slower (10~^-10~^ s) rate for the rearrangement of c-propyl to isopropyl ions [17].…”

Section: Ii) An Analogous Process Of Metastable Decomposition With Thmentioning

confidence: 99%

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Slow metastable decay process of (C3H7+
Foltin
¹
,
Grill
²
,
Rauth
³

et al. 1992
Phys. Rev. Lett.
12
0
1
0
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Besides the usual single-monomer evaporation, the {CiW^)niC^^i^) cluster ions produced by electron-impact ionization of neutral propane clusters have been observed to decay by an additional channel leading to evaporation of up to four C3H8 monomers. It is shown that this additional fragmentation channel is initiated by a new decay mechanism, i.e., the isomerization of an /i-propyl ion to a more stable 5^^r-propyl ion within the cluster.PACS numbers: 36.40.+d Studies of the fragmentation processes following electron-impact ionization of van der Waals (vdW) clusters of small molecules (e.g., nitrogen [1]) have provided valuable information on the dynamics of energized cluster ions (energy flow, mechanisms of dissociation, rearrangement processes within ionized clusters, etc.). In particular, slow fragmentation processes, usually referred to as the metastable decompositions of cluster ions, provide an important source of information [2]. Although there exist many studies of neat or mixed clusters of atoms and/or small molecules [2,3], much less is known about the metastable fragmentation of ionized clusters of polyatomic molecules (e.g., see [4]). Because prompt and metastable fragmentations of the ionized single molecules have been thoroughly studied and are well understood [5], simple hydrocarbons such as ethane and propane are especially suitable systems for dissociation studies.In this communication we report the results of our studies of metastable fragmentation of ionized clusters of propane and ethane. The dominant metastable dissociation process observed for stoichiometric and nonstoichiometric cluster ions is single-monomer evaporation, a well known and characterized (by the quasiequilibrium theory) process in the case of ionized vdW cluster ions [2]. None of the metastable decay reactions which occur for monomer ions (e.g., C3H8^-^ C3H7"'", etc.[5]) occurs in the cluster environment, apparently due to the fast energy transfer from intramolecular modes to intermolecular vibrations of cluster constituents. Moreover, besides the usual monomer evaporation, however, an additional metastable decay reaction involving the loss of up to four monomers from the (C3H7"*")(C3H8)« ion has been observed. Taking into account the various features (temporal evolution, energetics, fragmentation pattern) of this novel metastable decay process we have concluded that this decay reaction is driven by the isomerization reaction within the cluster of /i-propyl ions to isopropyl ions in the /is time regime. This reaction sequence constitutes a new mechanism for metastable dissociation of cluster ions (i.e., isolated-state-driven reactions), thereby adding a new variety to the two previously known metastable decay mechanisms of this kind, i.e., excimer-induced dissociation of rare-gas cluster ions [6] and the release of in-tramolecular vibrational quanta from N2 molecules within an ionized nitrogen cluster [1].The supersonic-beam-electron-impact ionization source and double-focusing mass spectrometer system has been described in det...

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Section: Ii) An Analogous Process Of Metastable Decomposition With Thsupporting

confidence: 81%

Section: Ii) An Analogous Process Of Metastable Decomposition With Thmentioning

confidence: 99%

Slow metastable decay process of (C3H7+
Foltin
¹
,
Grill
²
,
Rauth
³

et al. 1992
Phys. Rev. Lett.
12
0
1
0
View full text Add to dashboard Cite

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“…Primarily, it relates to homolytic reactions since radicals are often formed under the energetic influence upon molecules in an IC, e.g., in the course of fragmentation of molecular ions obtained in the electron impact (EI) ion source, or in the plasma generated in the chemical ionization (CI) source of mass spectrometers. They can further react with molecules [2][3][4][5][6][7]. On the other hand, fullerenes are well known as good acceptors of radicals due to a plenty of double C=C bonds in their molecules [8].…”

mentioning

confidence: 99%

Homolytic Reactive Mass Spectrometry of Fullerenes: Interaction of C₆₀ and C₇₀ with Ketones in the Electron Impact Ion Source of a Mass Spectrometer and the Comparison of Results with Those of Photochemical Reactions of C₆₀ with Several Ketones in Solution

Shilova

Lyakhovetsky

Belokon

et al. 2011

J. Am. Soc. Mass Spectrom.

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Our previous investigations showed that homolytic reactions of C 60 with a number of perfluoroorganic and organomercury(II) compounds occurring under electron impact (EI) in the ionization chamber (IC) of a mass spectrometer could predict the reactivity of C 60 towards these compounds in solution or solid state. To expand the scope of this statement, C 60 and C 70 have been reacted with ketones RCOR 1 , where R and R 1 are alkyl, aryl, benzyl, and CF 3 , in an IC under EI to yield products of the addition of R · and R 1 · radicals to the fullerenes, paramagnetic ones being stabilized by hydrogen addition and loss. Experimental evidence in support of a mechanism involving homolytic dissociation of ketone molecules via superexcited states to afford these radicals that react with the fullerenes at the IC surface has been obtained. As anticipated, the reactions between C 60 and several ketones conducted in solution under UV irradiation have afforded Me-, Ph-, and CF 3 -derivatives of C 60 . However, some other products have been identified by mass spectrometry and their formation is reasonably explained. When decalin has been employed as a solvent, decalinyl derivatives of the fullerene have been found among the products and the (9-decalinyl)fullerenyl radical has been registered by EPR. Thus, incomplete but reasonable conformity of the results of the reactions of fullerenes with ketones in an IC under EI with those of the reactions of the same reagents in solution under UV irradiation has been demonstrated, and the former results can predict the latter ones to a reasonable extent.

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“…Moreover, this type of the ionization chamber (IC) reactions is of a particular interest since such reactions are less dependent on solvent than the ionic processes and can be transferred to solution more easily. Certainly, homolytic bimolecular reactions occurring in ICs including those with fullerenes as reagents have been reported [10][11][12][13][14][15][16][17][18]. However, the amount of such examples is considerably less than of the examples of ion/molecule reactions.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Fullerenes with Organosilanes in the Ionization Chamber of a Mass Spectrometer under Electron Impact and the Reaction of C₆₀with Tetraphenylsilane in Solution under UV Irradiation

Lyakhovetsky

Shilova

Плешкова

et al. 2016

Journal of Spectroscopy

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C60was shown to react with organosilanes Me4Si, Ph2SiH2, Ph2MeSiH, Ph4Si, andα-naphthylphenylmethylsilane in the electron ionization ion source of a mass spectrometer with the transfer of the corresponding organic radicals (Me, Ph, andα-naphthyl) from the silanes to the fullerene. The reactions were accompanied by hydrogen addition to some products and hydrogen loss from them. C70reacted with Me4Si analogously. A reaction mechanism involving homolytic dissociation of the silanes under electron impact to the corresponding organic radicals, which react further with C60at the surface of the ionization chamber of the mass spectrometer to give the respective adducts, was offered. A mechanistic study of the reaction of C60with Me4Si supported it. No silicon containing derivatives of the fullerenes were found. C60reacted with Ph4Si in solution under UV irradiation in a similar fashion furnishing phenyl derivatives of the fullerene. These results provide an additional support to the hypothesis formulated earlier thatthe homolytic reactive mass spectrometry of fullerenes (the reactions of fullerenes with other species in the ionization chambers of mass spectrometers and their mass spectral monitoring)can predict the reactivity of them toward the same reagents in solution to a significant extent.

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Radical trapping in a mass spectrometer ion source. 1

Cited by 57 publications

References 3 publications

Slow metastable decay process of (C3H7+
Foltin
¹
,
Grill
²
,
Rauth
³

et al. 1992
Phys. Rev. Lett.
12
0
1
0
View full text Add to dashboard Cite

Slow metastable decay process of (C3H7+
Foltin
¹
,
Grill
²
,
Rauth
³

et al. 1992
Phys. Rev. Lett.
12
0
1
0
View full text Add to dashboard Cite

Homolytic Reactive Mass Spectrometry of Fullerenes: Interaction of C₆₀ and C₇₀ with Ketones in the Electron Impact Ion Source of a Mass Spectrometer and the Comparison of Results with Those of Photochemical Reactions of C₆₀ with Several Ketones in Solution

Interaction of Fullerenes with Organosilanes in the Ionization Chamber of a Mass Spectrometer under Electron Impact and the Reaction of C₆₀with Tetraphenylsilane in Solution under UV Irradiation

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Radical trapping in a mass spectrometer ion source. 1

Cited by 57 publications

References 3 publications

Slow metastable decay process of (C3H7+Foltin1, Grill2, Rauth3 et al. 1992Phys. Rev. Lett.12010View full textAdd to dashboardCite

Slow metastable decay process of (C3H7+Foltin1, Grill2, Rauth3 et al. 1992Phys. Rev. Lett.12010View full textAdd to dashboardCite

Homolytic Reactive Mass Spectrometry of Fullerenes: Interaction of C60 and C70 with Ketones in the Electron Impact Ion Source of a Mass Spectrometer and the Comparison of Results with Those of Photochemical Reactions of C60 with Several Ketones in Solution

Interaction of Fullerenes with Organosilanes in the Ionization Chamber of a Mass Spectrometer under Electron Impact and the Reaction of C60with Tetraphenylsilane in Solution under UV Irradiation

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About

Slow metastable decay process of (C3H7+
Foltin
¹
,
Grill
²
,
Rauth
³

et al. 1992
Phys. Rev. Lett.
12
0
1
0
View full text Add to dashboard Cite

Slow metastable decay process of (C3H7+
Foltin
¹
,
Grill
²
,
Rauth
³

et al. 1992
Phys. Rev. Lett.
12
0
1
0
View full text Add to dashboard Cite

Homolytic Reactive Mass Spectrometry of Fullerenes: Interaction of C₆₀ and C₇₀ with Ketones in the Electron Impact Ion Source of a Mass Spectrometer and the Comparison of Results with Those of Photochemical Reactions of C₆₀ with Several Ketones in Solution

Interaction of Fullerenes with Organosilanes in the Ionization Chamber of a Mass Spectrometer under Electron Impact and the Reaction of C₆₀with Tetraphenylsilane in Solution under UV Irradiation