Chemical ionization mass spectrometry

Field, F. H.

doi:10.1021/ar50002a002

Cited by 211 publications

(72 citation statements)

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“…Angular scattering data of CH3+ at 2-3 eV are consistent with the critical configuration of the decomposing intermediate being an almost linear species having the structure [D3C-H-CH#, with R(C-H-C) FZ 2.5 A. 3. The distributions of the relative product translational energy can be fitted by a statistical complex model at high collision energy; with decreasing collision energy increasing deviations between the experiment and the calculations were observed.…”

Section: Discussionsupporting

confidence: 62%

Dynamics of the Hydride Ion Transfer Reaction between CD3+ and CH4: A Crossed Beam Scattering Study

Žabka¹,

Fárnı́k²,

Dolejšek³

et al. 1995

J. Phys. Chem.

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The hydride ion transfer reaction leading to CH3+ in collisions of CD3+ and C& was investigated in beam scattering experiments in the collision energy range 1-3 eV (center-of-mass). The reaction proceeds through the formation of an intermediate complex; the angular scattering data are consistent with a structure of the critical configuration of the intermediate being (D,C-H-CH,)+ with R(C-H-C) M 2.5 A. The formationof CD2H+, which is viewed as a backward decomposition of the complex to the reactants accompanied by a partial H-D scrambling, involves an analogous critical configuration at T = 3 eV.

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Section: Discussionsupporting

confidence: 62%

Dynamics of the Hydride Ion Transfer Reaction between CD3+ and CH4: A Crossed Beam Scattering Study

Žabka¹,

Fárnı́k²,

Dolejšek³

et al. 1995

J. Phys. Chem.

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“…Electron impact (EI) and chemical ionization (CI) (1,2) predominate. While claims for each have been made for some degrees of "soft ionization", that is, ionization without parent ion fragmentation, more often than not, the base peaks are due to fragment ions.…”

Section: Introductionmentioning

confidence: 99%

An overview of organic molecule soft ionization using vacuum ultraviolet laser radiation

Shi¹,

Lipson²

2005

Can. J. Chem.

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The utility of coherent vacuum ultraviolet (VUV) single-photon ionization (SPI) combined with time-of-flight mass spectrometry (TOF-MS) for organic molecule detection by parent mass is explored in this short review. Nonresonant tripling in phase-matched Xe-Ar gas mixtures was used to generate photons at a fixed energy of 10.5 eV. Representative organic molecules with different functional groups were examined, including aliphatic and aromatic alkanes, alkenes, alkynes, alkanols, ethers, amines, aldehydes, ketones, carboxylic acids, and esters. In almost every case, the intensity of the resultant parent molecular ion peak detected by TOF-MS was found to be superior to that obtained using 70 eV electron impact (EI), and comparable to that obtained with 12 eV EI. In those instances when fragmentation reactions did occur, the resultant ions were similar to those found using EI but with significantly reduced mass spectral intensities. It was still possible to establish one dominant fragmentation pathway that could be used for molecular identification even if the parent molecular ion was not the strongest feature in the spectrum, for example, in the case of alcohols, alcohol clusters, and alcohol-ether adducts. Several of the fragment ions were metastably broadened. Not surprisingly, their known appearance energies or estimated reaction enthalpies were very similar to the fixed photon energy used. The success of using VUV for organic molecule soft ionization is attributed to the low photon energy that removes predominantly a π-or non-bonding electron from the functionalized species. As most organic compounds have ionization potentials in the 10.5 eV region, this approach is expected to be near universal. Résumé :Dans cette courte revue, on examine l'utilité d'une ionisation par un photon unique dans l'ultraviolet lointain cohérent combinée avec un spectromètre de masse à temps d'envol (SM-TDE) pour la détection de molécules organiques à l'aide de la masse parente. Le triplage non résonant de mélanges de gaz Xe-Ar en phase a été utilisé pour gé-nérer des photons d'énergie fixe de 10,5 eV. Des molécules organiques représentatives portant divers groupes fonctionnels ont été examinées, y compris des alcanes, des alcènes, des alcynes, des alcools, des éthers, des amines, des aldéhydes, des cétones, des acides carboxyliques et des esters aliphatiques et aromatiques. Dans pratiquement tous les cas, il a été trouvé que l'intensité du pic de l'ion moléculaire parent qui en résulte telle que détectée par SM-TDE est supérieure à celle obtenue en utilisant un impact électronique (IE) de 70 eV, et qu'elle est comparable à celle obtenue avec un IE de 12 eV. Dans les cas où des réactions de fragmentation se sont produites, les ions qui en résultent sont semblables à ceux observés avec un IE, mais les intensités des masses spectrales sont de beaucoup réduites. Il est toujours possible d'établir une voie de fragmentation dominante qui pourrait être utilisée pour l'identification molécu-laire, même si l'ion moléculaire parent n'est pas l...

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“…Ces deux rkactions sont en cornpCtition avec les rCactions de condensation et la rCaction 3 l'est avec la rCaction de transfert de proton en rCsonnance (11). En prksence de M2B2 le rnCcanisrne est sirnilaire: la rCaction 3 Ctant remplacCe par la suivante: [7] ter.1-C5Hlli + M2B2 -M2B1 + tert-C5HI17-…”

Section: Pr~oclrrils Cllirniqlre~unclassified

Réactions ion–molécule dans les méthylbutènes: radiolyse du méthane

Collin¹

1976

Can. J. Chem.

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)lllurtertie~lt des Scierlces Piires, UrriversitC rlri Qlrbbec h Cl~icoirtir,ii, Cllicoiltirni, QlrCbec G7H 2BI GUY J. COLLIN. Can. J. Chem. 54, 555 (1976).La radiolyse du mithane en prisence de l'un des trois mithylbutknes provoque une isornirisation importante de I'additif. Les observations rapporties sont compatibles avec un mecanisme ionique initii par les ions CHs+ et CzHs+ formis dans la radiolyse directe du mithane. L'isomirisation progresse dans un micanisme en chaine courte oh le porteur de chaine pourrait &tre l'ion tet.t-CsHIl+. Dans le-cas du mithyl-3-butkne-1, l'ion (CH3)2CHCHCH3+ initialement forme s'isomirise en ter~/-CsHII+ avant d'amorcer l'isomirisation observie. GUY J. COLLIN. Can. J. Chem. 54, 555 (1976).The radiolysis of gaseous methane has been studied in the presence of one of the three methylbutenes. We have observed an important isornerization of the added olefin. An ionic mechanism initiated by the CH5+ and C2H5+ ions seems to be compatible with the observations reported. Isomerization proceeds through a chain mechanism where the chain carrier may be the teri-CsHII+ ion. In the presence of 3-methyl-1-butene, the initially formed (CH3);CHCHCH3-ion isomerizes to the tertiary structure before producing the observed isomerization. IntroductionRCcemment, nous avons montrC que l'irradiation gamma du nCopentane gazeux en prCsence de dirivCs insaturis comme les mCthylbutknes provoque le dCplacement de la double liaison le long de la chaine carbone-carbone. Le micanisme suggtrC propose un nlCcanisn~e ionique initii par l'ion tert-C4Hgi form6 dans la radiolyse directe du niopentane. L'ion tert-C5HII+ sert de porteur de chaine. Ainsi dans le cas du nlCthyl-2-butkne-1 (M2B1) le mCcanisme serait le suivant:

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Chemical ionization mass spectrometry

Cited by 211 publications

References 0 publications

Dynamics of the Hydride Ion Transfer Reaction between CD3+ and CH4: A Crossed Beam Scattering Study

Dynamics of the Hydride Ion Transfer Reaction between CD3+ and CH4: A Crossed Beam Scattering Study

An overview of organic molecule soft ionization using vacuum ultraviolet laser radiation

Réactions ion–molécule dans les méthylbutènes: radiolyse du méthane

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