Theoretical chemical ionization rate constants of the concurrent reactions of hydronium ions (H<sub>3</sub>O<sup>+</sup>) and oxygen ions (O) with selected organic iodides

Strekowski, Rafal; Alvarez, Coralie; Petrov-Stojanović, Jeanne; Hagebaum‐Reignier, Denis; Wortham, Henri

doi:10.1002/jms.4349

Cited by 3 publications

(3 citation statements)

References 39 publications

(81 reference statements)

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“…For any ion-molecule interaction, longrange attractive forces (ion-induced dipole and ion-dipole) contribute to determining the rate coefficients. Many theoretical approaches such as the Langevin model, ADO, and classical parametrized trajectory methods based on the capture collision theory have been used significantly [29][30][31]. The long-range forces deviate the approaching reactants and draw them into closer trajectories to favor a reaction [26].…”

Section: Rate Coefficients Calculationmentioning

confidence: 99%

Gaussian Process Regression (GPR) Method for the Prediction of Rate Coefficients of Gas-phase Reactions in Chemical Ionization Mass Spectrometry

Bhatia

2022

Preprint

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Reaction kinetics of chemical ionization mass spectrometry (CI-MS) based ion-molecule reactions is an important component in the quantification of trace-level volatile organic compounds (VOCs). The rate coefficients of such CI-MS reactions are predicted using the Gaussian process regression (GPR) machine learning method from the dipole moment, polarizability, and molecular weight of the molecules, mitigating experimental complexity in CI-MS rate coefficient estimation. GPR can make predictions combining prior knowledge (kernel function) which is considered the heart of the GPR model and provide uncertainty measures over predictions. A suitable kernel combination with proper tuning of parameters can make the Gaussian process more robust and powerful. Various kernel combinations, such as kernel addition and multiplication, are tested in the GPR prediction of rates. A blend of radial basis function (RBF), white noise, and squared exponential kernel performs better, and the predicted rates are in close agreement with the experimental rates. GPR provides an alternative to the capture collision rates and can be useful when there are no experimental data available and/or the available data contain large uncertainty in the rate coefficients.

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Section: Rate Coefficients Calculationmentioning

confidence: 99%

Gaussian Process Regression (GPR) Method for the Prediction of Rate Coefficients of Gas-phase Reactions in Chemical Ionization Mass Spectrometry

Bhatia

2022

Preprint

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“…Besides the k‐ratio, which if calculated (Strekowski et al, 2019) and experimentally (Zhao & Zhang, 2004) proven may have an error margin of up to 50% to the mean value, further approximations are made which might have a huge impact to the determination of a certain compound concentration (Blake et al, 2009). The temperatures at which the ion–molecule collisions take place can be estimated, but it remains unclear if this temperature accurately reflects the ion chemistry inside the drift tube.…”

Section: Introductionmentioning

confidence: 99%

The potential of NO⁺ and O₂^+• in switchable reagent ion proton transfer reaction time‐of‐flight mass spectrometry

Hegen

Gómez

Schlögl

et al. 2022

Mass Spectrometry Reviews

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Selected ion flow tube mass spectrometry (SIFT‐MS) and proton transfer reaction mass spectrometry with switchable reagent ion capability (PTR+SRI‐MS) are analytical techniques for real‐time qualification and quantification of compounds in gas samples with trace level concentrations. In the detection process, neutral compounds—mainly volatile organic compounds—are ionized via chemical ionization with ionic reagents or primary ions. The most common reagent ions are H3O+, NO+ and O2+•. While ionization with H3O+ occurs by means of proton transfer, the ionization via NO+ and O2+• offers a larger variety on ionization pathways, as charge transfer, hydride abstraction and so on are possible. The distribution of the reactant into various reaction channels depends not only on the usage of either NO+ or O2+•, but also on the class of analyte compounds. Furthermore, the choice of the reaction conditions as well as the choice of either SIFT‐MS or PTR+SRI‐MS might have a large impact on the resulting products. Therefore, an overview of both NO+ and O2+• as reagent ions is given, showing differences between SIFT‐MS and PTR+SRI‐MS as used analytical methods revealing the potential how the knowledge obtained with H3O+ for different classes of compounds can be extended with the usage of NO+ and O2+•.

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“…Based on trajectory simulations between a point-like charged particle and a polar rigid rod, Su and Chesnavich (1982) obtained a parameterized model for the collision rate coefficient of ion-dipole collisions. This model has been shown to give rather good results for systems of small molecules and ions (Amelynck et al, 2005;Strekowski et al, 2019;Midey et al, 2001;Williams et al, 2004;Woon and Herbst, 2009) and is widely used in atmospheric sciences (e.g., in the Atmospheric Cluster Dynamics Code; McGrath et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Modeling approaches for atmospheric ion–dipole collisions: all-atom trajectory simulations and central field methods

Neefjes

Halonen²,

Vehkamäki³

et al. 2022

Atmos. Chem. Phys.

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Abstract. Ion–dipole collisions can facilitate the formation of atmospheric aerosol particles and play an important role in their detection in chemical ionization mass spectrometers. Conventionally, analytical models, or simple parametrizations, have been used to calculate the rate coefficients of ion–dipole collisions in the gas phase. Such models, however, neglect the atomistic structure and charge distribution of the collision partners. To determine the accuracy and applicability of these approaches under atmospheric conditions, we calculated collision cross sections and rate coefficients from all-atom molecular dynamics collision trajectories, sampling the relevant range of impact parameters and relative velocities, and from a central field model using an effective attractive interaction fitted to the long-range potential of mean force between the collision partners. We considered collisions between various atmospherically relevant molecular ions and dipoles and charged and neutral dipolar clusters. Based on the good agreement between collision cross sections and rate coefficients obtained from molecular dynamics trajectories and a generalized central field model, we conclude that the effective interactions between the collision partners are isotropic to a high degree, and the model is able to capture the relevant physicochemical properties of the systems. In addition, when the potential of mean force is recalculated at the respective temperatures, the central field model exhibits the correct temperature dependence of the collision process. The classical parametrization by Su and Chesnavich (1982), which combines a central field model with simplified trajectory simulations, is able to predict the collision rate coefficients and their temperature dependence quite well for molecular systems, but the agreement worsens for systems containing clusters. Based on our results, we propose the combination of potential of mean force calculation and a central field model as a viable and elegant alternative to the brute force sampling of individual collision trajectories over a large range of impact parameters and relative velocities.

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Theoretical chemical ionization rate constants of the concurrent reactions of hydronium ions (H₃O⁺) and oxygen ions (O) with selected organic iodides

Cited by 3 publications

References 39 publications

Gaussian Process Regression (GPR) Method for the Prediction of Rate Coefficients of Gas-phase Reactions in Chemical Ionization Mass Spectrometry

Gaussian Process Regression (GPR) Method for the Prediction of Rate Coefficients of Gas-phase Reactions in Chemical Ionization Mass Spectrometry

The potential of NO⁺ and O₂^+• in switchable reagent ion proton transfer reaction time‐of‐flight mass spectrometry

Modeling approaches for atmospheric ion–dipole collisions: all-atom trajectory simulations and central field methods

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Theoretical chemical ionization rate constants of the concurrent reactions of hydronium ions (H3O+) and oxygen ions (O) with selected organic iodides

Cited by 3 publications

References 39 publications

Gaussian Process Regression (GPR) Method for the Prediction of Rate Coefficients of Gas-phase Reactions in Chemical Ionization Mass Spectrometry

Gaussian Process Regression (GPR) Method for the Prediction of Rate Coefficients of Gas-phase Reactions in Chemical Ionization Mass Spectrometry

The potential of NO+ and O2+• in switchable reagent ion proton transfer reaction time‐of‐flight mass spectrometry

Modeling approaches for atmospheric ion–dipole collisions: all-atom trajectory simulations and central field methods

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Product

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Theoretical chemical ionization rate constants of the concurrent reactions of hydronium ions (H₃O⁺) and oxygen ions (O) with selected organic iodides

The potential of NO⁺ and O₂^+• in switchable reagent ion proton transfer reaction time‐of‐flight mass spectrometry