Neutralization-reionization mass spectrometry (NRMS)

Wesdemiotis, Chrysostomos; McLafferty, Fred W.

doi:10.1021/cr00079a001

Cited by 363 publications

(132 citation statements)

References 29 publications

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“…48 Several cases have been reported that demonstrate the distinction of isomeric compounds via NRMS, 42,49,50 while corresponding CID experiments only gave rise to identical spectra for the isomers. It has been reported that NRMS can also provide valuable information about the structures and chemistries of neutrals and ions derived from small organic and inorganic molecules, 11,42,43,51,52 organometallic compounds 53 and relatively large molecules including fullerenes, 54 peptides, 55,56 and nucleotides and related species. 57,58 The studies alluded to here constitute a small subset of the applications of NRMS.…”

Section: Reaction (15) Collisional Ionizationmentioning

confidence: 99%

Charge permutation reactions in tandem mass spectrometry

McLuckey

2004

J. Mass Spectrom.

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Central to the tandem mass spectrometry experiment is the process that gives rise to product ions, i.e. the reaction intermediate to stages of mass analysis. Changes in mass or charge of the parent ion (or both) are generally readily detected by all forms of tandem mass spectrometry. Charge changing, or charge permutation, reactions have a long history in mass spectrometry. However, with the advent of new ionization methods, such as electrospray ionization, and the expansion of tandem mass spectrometry instrumentation to include ion trapping instruments, the past decade has seen a major increase in the types of charge permutation reactions that can be studied. Most charge permutation reactions involve electrons or protons as the charge mediating agents. This report, therefore, provides an overview of charge permutation reactions involving protons or electrons. Particular emphasis is placed on processes that involve interactions of precursor ions with gaseous neutral species, electrons or oppositely charged ions. Charge permutation reactions involving electron gain/loss are described first according to a rough order of the energy required for the reaction beginning with the most endoergic reactions and ending with the most exoergic reactions. An analogous approach is then taken with charge permutation reactions involving proton gain/loss. Important charge permutation reactions discussed herein, among others, include those referred to as charge inversion, charge stripping, electron capture dissociation, collision-induced ionization and charge separation. These reaction types, and others described herein, are the subjects of active research and are also finding use in many current areas of application.

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Section: Reaction (15) Collisional Ionizationmentioning

confidence: 99%

Charge permutation reactions in tandem mass spectrometry

McLuckey

2004

J. Mass Spectrom.

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“…The chemistry of carbenes in solution is well documented (1,2) and methylene, the simplest carbene, is a well-understood compound (3). The electronic and molecular structures of singlet and triplet methylene and the energy difference between these states (AEs,) has been determined both experimentally (4) and theoretically (5).…”

Section: Resultsmentioning

confidence: 99%

“…Although many alkylcarbenes have been spectroscopically characterized under matrix isolation conditions (1,2), their direct observation in solution is very difficult because they readily undergo 1,2-H migration. However, substituents directly attached to the carbenic carbon can have a dramatic influence on the activation barriers for the 1,2-H shift to this centre (7,8).…”

Section: Resultsmentioning

confidence: 99%

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Intramolecular 1,2-alkyl shifts in unsymmetric dialkoxycarbenes studied by very low vapour pressure (VLVP) pyroiysis – mass spectrometry

Suh¹,

Pole²,

Warkentin³

et al. 1996

Can. J. Chem.

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Methoxy-(2,2,2-trifluoroethoxy)carbene radical cations, CH,O-C-OCH,CF,'+, I", are cleanly generated by the dissociative electron ionization (EI) of 2-methoxy-5,5-dimethyl-2-(2,2,2-trifluoroethoxy)-~-1 ,3,4-oxadiazoline I. Neutralization-reionization (NR) mass spectrometry of the neutral carbene 1, generated by one-electron reduction of I'+, shows no recovery ion signal and thus 1 is not a viable species within the ks time scale of the experiment. Very low vapour pressure (VLVP) pyrolysis -mass spectrometry of I in conjunction with (multiple) collision experiments shows that 1 completely isomerizes, via a 1,2-trifluoroethyl shift, into methyl 3,3,3-trifluoropropionate, CF,CH,C(=O)OCH,, l a . This technique was also used to study the related dialkoxycarbenes C,H,O-C-OCH,CF,, 2, CH,O-C-0C2H,, 3, and CH,O-C-OCH(CH,),, 4, generated from the corresponding 2,2-dialkoxy-5,5-dimethyl-A3-1 ,3,4-oxadiazolines. The pyrolytically generated carbene 2 behaves analogously to 1 and completely isomerizes to ethyl 3,3,3-trifluoropropionate, 2a. The neutral carbenes 3 and 4 undergo only a partial isomerization via 1,2-alkyl shifts in which the ethyl and isopropyl groups show a slightly greater migratory aptitude, respectively, than the methyl group. The differences in migratory aptitude are explained in terms of a transition state model similar to that of a 1,2-H shift in carbenes, with development of negative charge in the migrating group. The greater migratory aptitude of CF,CH,, as compared to CH, and CH,CH2, is attributed to the stabilization of negative charge in the transition state by strongly electron-withdrawing p-fluorines whereas the differences in migratory aptitude between the alkyl groups in 3 and 4 are largely due to the greater polarizability of isopropyl and ethyl groups, as compared to the methyl group.Key words: dialkoxycarbenes, pyrolysis, tandem mass spectrometry.Resume : On peut gCnCrer proprement les cations radicaux mtthoxy-(2.2.2-trifluoroCthoxy)carbknes, CH30-C-0CH2CF,'+, 1'+, en procCdant ? I une ionisation Clectronique (IE) dissociative de la 2-mCthoxy-5,5-dim~thyl-2-(2,2,2-trifluoroCthoxy)-~3-1 ,3,4-oxadiazoline, I. La spectroscopie par neutralisation-rkionisation (NR) du carbkne neutre, 1, gCnCrC par une rCduction un electron du 1". ne prksente pas de signal correspondant ii de la rCcupCration d'ion et le composC 1 n'est donc pas une espkce approprike ii I'tchelle de temps, ks, de I'expCrience: La spectromCtrie de masse du composC I avec pyrolyse ii trks basse tension de vapeur (VLVP), rCalisCe de concert avec des expkriences de (multiples) collisions ont montrC que le composC 1 s'isomkrise complktement, par le biais d'un dCplacement-1,2 d'un groupe trifluoroCthyle, en un 3,3,3-trifluoropropionate de mCthyle, CF,CH,C(=O)OCH,, la. On a aussi utilisk cette technique pour Ctudier des dialkoxycarbknes apparentis : C2HjO-C-OCH,CF,, 2, CH,O-C-OC,H,, 3, et CH,O-C-OCH(CH,),, 4, gCnCrCs a parti des 2,2-dialko~~-5,5-dirnCth~l-~~-1,3,4-oxadiazolines correspondantes. Le carbkne 2 prCparC d'une f a~o n py...

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“…To circumvent these limitations, the neutrals studied can be ionized and then analyzed in a standard way using electromagnetic fields. 9 Although "gentle" ionization methods exist nowadays (e.g., electrospray ionization 10 ), the ionization often results in further fragmentation and in multiple ionization. Each of these processes can lead to a significant increase of complexity in the measured mass-to-charge spectrum.…”

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confidence: 99%

Cryogenic micro-calorimeters for mass spectrometric identification of neutral molecules and molecular fragments

Novotný

Allgeier

Enss

et al. 2015

Journal of Applied Physics

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We have systematically investigated the energy resolution of a magnetic micro-calorimeter (MMC) for atomic and molecular projectiles at impact energies ranging from E ≈ 13 to 150 keV. For atoms we obtained absolute energy resolutions down to ∆E ≈ 120 eV and relative energy resolutions down to ∆E/E ≈ 10 −3 . We also studied in detail the MMC energy-response function to molecular projectiles of up to mass 56 u. We have demonstrated the capability of identifying neutral fragmentation products of these molecules by calorimetric mass spectrometry. We have modeled the MMC energy-response function for molecular projectiles and conclude that backscattering is the dominant source of the energy spread at the impact energies investigated. We have successfully demonstrated the use of a detector absorber coating to suppress such spreads. We briefly outline the use of MMC detectors in experiments on gas-phase collision reactions with neutral products. Our findings are of general interest for mass spectrometric techniques, particularly for those desiring to make neutral-particle mass measurements.

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Neutralization-reionization mass spectrometry (NRMS)

Cited by 363 publications

References 29 publications

Charge permutation reactions in tandem mass spectrometry

Charge permutation reactions in tandem mass spectrometry

Intramolecular 1,2-alkyl shifts in unsymmetric dialkoxycarbenes studied by very low vapour pressure (VLVP) pyroiysis – mass spectrometry

Cryogenic micro-calorimeters for mass spectrometric identification of neutral molecules and molecular fragments

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