Gas-phase solvated negative ions

Takashima, Keiko; Riveros, José M.

doi:10.1002/(sici)1098-2787(1998)17:6<409::aid-mas2>3.0.co;2-j

Cited by 71 publications

(12 citation statements)

References 220 publications

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“…However, as shown in several studies, 17,18,52–54 the rate constants of the ligand‐switching reactions typically decrease with increasing water cluster size n . Therefore, increasing the sample gas humidity and thus the humidity in the reaction region results in a decrease in the sensitivity.…”

Section: Ionization Pathways Resulting In the Formation Of Positive Pmentioning

confidence: 80%

“…Thus, the permanent dipole moment and the polarizability of the analyte molecule seem to be key parameters to predict whether ligand-switching reactions occur. 10,17,18,52 However, as shown in several studies, 17,18,[52][53][54] the rate constants of the ligand-switching reactions typically decrease with increasing water cluster size n. Therefore, increasing the sample gas humidity and thus the humidity in the reaction region results in a decrease in the sensitivity. In particular, IMS instruments operated at ambient pressure thus suffer from a sample gas humidity-dependent detection of analytes.…”

Section: Reactions Of Hydrated Hydronium Cations H 3 O + (H 2 O) Nmentioning

confidence: 95%

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Formation of positive product ions from substances with low proton affinity in high kinetic energy ion mobility spectrometry

Allers

Kirk

Schaefer

et al. 2021

Rapid Comm Mass Spectrometry

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Rationale: Ion mobility spectrometry (IMS) instruments are typically equipped with atmospheric pressure chemical ionization (APCI) sources operated at ambient pressure. However, classical APCI-IMS suffers from a limited ionization yield for nonpolar substances with low proton affinity (PA). This is mainly due to ion clustering processes, especially those that involve water molecules, inhibiting the ionization of these substances. Methods: High Kinetic Energy (HiKE)-IMS instruments are operated at decreased pressures and high reduced electric field strengths. As most clustering reactions are inhibited under these conditions, the ionization yield for nonpolar substances with low PA in HiKE-IMS should differ from that in classical APCI-IMS. To gain first insights into the ionization capabilities and limitations of HiKE-IMS, we investigated the ionization of four model substances with low PA in HiKE-IMS using HiKE-IMS-MS as a function of the reduced electric field strength. Results: The four model substances all have proton affinities between those of H 2 O and (H 2 O) 2 but exhibit different ionization energies, dipole moments, and polarizabilities. As expected, the results show that the ionization yield for these substances differs considerably at low reduced electric field strengths due to ion cluster formation. In contrast, at high reduced electric field strengths, all substances can be ionized via charge and/or proton transfer in HiKE-IMS. Conclusions: Considering the detection of polar substances with high PAs, classical ambient pressure IMS should reach better detection limits than HiKE-IMS. However, considering the detection of nonpolar substances with low PA that are not detected, or only difficult to detect, at ambient pressure, HiKE-IMS would be beneficial. 1 | INTRODUCTION Due to their high sensitivity, fast response times, and compact design, ion mobility spectrometers are commonly used in safety and security applications such as the detection of chemical warfare agents, 1,2 toxic industrial chemicals, 3,4 drugs, 5,6 and explosives. 7-9 Basically, ion mobility spectrometry (IMS) instruments can be divided by their principle of ion separation. In this work, a drift tube (DT) ion mobility spectrometer is used. In DT-IMS, ions are separated by their motion along the axis of a drift tube driven by a homogeneous static electric field. To initiate the measurement, an ion packet is injected into the drift tube. During their motion, the ions are separated based on the absolute value of their ion mobility in the present drift gas. At the end of the drift tube, the ions are captured by a detector that converts

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Section: Ionization Pathways Resulting In the Formation Of Positive Pmentioning

confidence: 80%

Section: Reactions Of Hydrated Hydronium Cations H 3 O + (H 2 O) Nmentioning

confidence: 95%

Formation of positive product ions from substances with low proton affinity in high kinetic energy ion mobility spectrometry

Allers

Kirk

Schaefer

et al. 2021

Rapid Comm Mass Spectrometry

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“…4,5 The ion−molecule nucleophilic substitution (S N 2) reaction is a fundamental organic reaction. 6−9 Numerous experimental and computational studies on microsolvated S N 2 reactions revealed that individual solvent molecules have multiple influences on the reaction, 7,10 including reduced reactivity, 5,11−16 altered reaction dynamics, 17−22 complex reaction mechanisms, 23−28 and the enhanced α-effect. 29−32 One way that protic solvent (HR) influences the ion− molecule S N 2 reaction is proton transfer within the nucleophile X − (HR) to form an alternative nucleophile (XH)R − , which will, in principle, induce a new S N 2 product channel, (XH)R − + CH 3 Y → CH 3 R + XH + Y − .…”

mentioning

confidence: 99%

Single Solvent Molecules Induce Dual Nucleophiles in Gas-Phase Ion–Molecule Nucleophilic Substitution Reactions

Zhao

et al. 2021

J. Phys. Chem. Lett.

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Direct dynamics simulation of singly hydrated peroxide ion reacting with CH3Cl reveals a new product channel that forms CH3OH + Cl– + HOOH, besides the traditional channel that forms CH3OOH + Cl– + H2O. This finding shows that singly hydrated peroxide ion behaves as a dual nucleophile through proton transfer between HOO–(H2O) and HO–(HOOH). Trajectory analysis attributes the occurrence of the thermodynamically and kinetically unfavored HO–-induced pathway to the entrance channel dynamics, where extensive proton transfer occurs within the deep well of the prereaction complex. This study represents the first example of a single solvent molecule altering the nucleophile in a gas-phase ion–molecule nucleophilic substitution reaction, in addition to reducing the reactivity and affecting the dynamics, signifying the importance of dynamical effects of solvent molecules.

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“…268,269 Another class of reaction mechanism, namely nucleophilic S N 2 substitution forming (H 2 O) n X − , was observed for the reactions of methyl halides (CH 3 X; X = F, Cl, Br, I) with (H 2 O) n OH − . [270][271][272][273][274][275][276][277][278] In the S N 2 reaction, the OH − anion (nucleophile) attacks the carbon center of the methyl halide inducing the C─X bond cleavage and the formation of a new C─OH bond occurs simultaneously. The reactivity was strongly influenced by the hydration as demonstrated by the pioneering work of Bohme and Mackay, 270 where the rate constant for the reaction CH 3 Br + (H 2 O) n OH − decreased by several orders of magnitude from n = 0 to n = 3.…”

Section: Other Halogen-containing Clustersmentioning

confidence: 99%

Mass spectrometry of aerosol particle analogues in molecular beam experiments

Fárnı́k

Lengyel

2017

Mass Spectrometry Reviews

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Nanometer-size particles such as ultrafine aerosol particles, ice nanoparticles, water nanodroplets, etc, play an important, however, not yet fully understood role in the atmospheric chemistry and physics. These species are often composed of water with admixture of other atmospherically relevant molecules. To mimic and investigate such particles in laboratory experiments, mixed water clusters with atmospherically relevant molecules can be generated in molecular beams and studied by various mass spectrometric methods. The present review demonstrates that such experiments can provide unprecedented details of reaction mechanisms, and detailed insight into the photon-, electron-, and ion-induced processes relevant to the atmospheric chemistry. After a brief outline of the molecular beam preparation, cluster properties, and ionization methods, we focus on the mixed clusters with various atmospheric molecules, such as hydrated sulfuric acid and nitric acid clusters, N O and halogen-containing molecules with water. A special attention is paid to their reactivity and solvent effects of water molecules on the observed processes.

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Gas-phase solvated negative ions

Cited by 71 publications

References 220 publications

Formation of positive product ions from substances with low proton affinity in high kinetic energy ion mobility spectrometry

Formation of positive product ions from substances with low proton affinity in high kinetic energy ion mobility spectrometry

Single Solvent Molecules Induce Dual Nucleophiles in Gas-Phase Ion–Molecule Nucleophilic Substitution Reactions

Mass spectrometry of aerosol particle analogues in molecular beam experiments

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