Atmospheric chemistry of iodine anions: elementary reactions of I−, IO−, and IO2− with ozone studied in the gas-phase at 300 K using an ion trap

Teiwes, Ricky; Elm, Jonas; Handrup, Karsten; Jensen, Ellen P; Bilde, Merete; Pedersen, H. B.

doi:10.1039/c8cp05721d

Cited by 23 publications

(28 citation statements)

References 51 publications

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“…Based on a (calculated) literature value for the free energy of formation of I − (H 2 O) 1 of −6.1 kcal mol −1 (Teiwes et al, 2019), we derive an equilibrium constant (at 298 K) of K 6 = 1.16 × 10 −15 cm 3 molecule −1 for the formation and thermal dissociation of I − (H 2 O) 1 : During extended operation of the CIMS, changes in sensitivity were captured by monitoring the primary ion signal (I − and its water cluster). Background signals at each of the mass-to-charge ratios monitored were obtained by passing the sampled air through a tubular scrubber (aluminium) filled with stainless-steel wool heated to 120 • C.…”

Section: Methodsmentioning

confidence: 99%

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Iodide CIMS and m∕z 62: the detection of HNO3 as NO3− in the presence of PAN, peroxyacetic acid and ozone

et al. 2021

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Abstract. Chemical ionisation mass spectrometry (CIMS) using I− (the iodide anion), hereafter I-CIMS, as a primary reactant ion has previously been used to measure NO3 and N2O5 both in laboratory and field experiments. We show that reports of large daytime mixing ratios of NO3 and N2O5 (both usually present in detectable amounts only at night) are likely to be heavily biased by the ubiquitous presence of HNO3 in the troposphere and lower stratosphere. We demonstrate in a series of laboratory experiments that the CIMS detection of HNO3 at m/z 62 using I− ions is efficient in the presence of peroxy acetyl nitric anhydride (PAN) or peroxyacetic acid (PAA) and especially O3. We have characterised the dependence of the sensitivity to HNO3 detection on the presence of acetate anions (CH3CO2-, m/z 59, from either PAN or PAA). The loss of CH3CO2- via conversion to NO3- in the presence of HNO3 may represent a significant bias in I-CIMS measurements of PAN and PAA in which continuous calibration (e.g. via addition of isotopically labelled PAN) is not carried out. The greatest sensitivity to HNO3 at m/z 62 is achieved in the presence of ambient levels of O3 whereby the thermodynamically disfavoured, direct reaction of I− with HNO3 to form NO3- is bypassed by the formation of IOx-, which reacts with HNO3 to form, for example, iodic acid and NO3-. The ozone and humidity dependence of the detection of HNO3 at m/z 62 was characterised in laboratory experiments and applied to daytime, airborne measurements in which good agreement with measurements of the I−(HNO3) cluster ion (specific for HNO3 detection) was obtained. At high ozone mixing ratios, we show that the concentration of I− ions in our ion–molecule reactor (IMR) is significantly depleted. This is not reflected by changes in the measured I− signal at m/z 127 as the IOx- formed does not survive passage through the instrument but is likely detected after fragmentation to I−. This may result in a bias in measurements of trace gases using I-CIMS in stratospheric air masses unless a calibration gas is continuously added or the impact of O3 on sensitivity is characterised.

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Section: Methodsmentioning

confidence: 99%

“…The second explanation is that the presence of O 3 results in the generation of further reagent ions that can react with HNO 3 . Iodide anions are known to react with O 3 , leading, in a series of exothermic reactions, to the formation of iodate (Williams et al, 2002;Teiwes et al, 2018;Bhujel et al, 2020).…”

Section: Methodsmentioning

confidence: 99%

Iodide CIMS and m∕z 62: the detection of HNO3 as NO3− in the presence of PAN, peroxyacetic acid and ozone

et al. 2021

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“…Second order rate constants (k 2nd ) were determined from measured k 1st using the approximate ozone number density present within the ion trap at a given output from the external ozone generator. The reported theoretical second order rate constant for iodide ozonolysis (8.7 × 10 -13 cm 3 molecules -1 s -1 ) (Teiwes et al, 2018) was used to estimate the amount ozone present within the ion trap. Under high ozone output conditions, ozone concentration within the ion trap was estimated at 2.8 × 10 11 molecules cm -3 , while low output resulted in 4.6 × 10 10 molecules cm -3 of ozone.…”

Section: Kineticsmentioning

confidence: 99%

Reaction of ionised steryl esters with ozone in the gas phase

Hancock

Maccarone

Poad

et al. 2019

Chemistry and Physics of Lipids

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Cholesterol is an ubiquitous membrane lipid, that also serves as a precursor to many steroid hormones. The 5,6 carbon-carbon double bond on the tetracyclic carbon backbone of cholesterol is an attractive target for ozone with the reaction giving rise to a wide range of possibly bioactive molecules. Despite this, little is known about the ozonolysis of cholesterol esters, which often possess an additional double bond(s) on the fatty acyl chain. Understanding the intrinsic gas phase reaction of ozone with the two disparate double bond positions on cholesteryl esters can inform our understanding of these processes in vivo, particularly reactions occurring at the air-water interface (e.g., tear film lipid layer) and on the surfaces of the body where these cholesterol and cholesteryl esters may be present (e.g., sebum). In the present work we describe the gas phase ozonolysis of lithium and sodium cations formed from three steryl esters: two isomeric for double bond position (cholestanyl oleate and cholesteryl stearate), and a third with carbon-carbon double bonds present in both the sterol ring system and fatty acyl chain (cholesteryl oleate). We confirm the enhanced reactivity of the endocyclic carbon-carbon double bond with ozone over double bonds present in the acyl chain, and elucidate competitive interactions between the two double bond positions during ozonolysis. Elucidation of the mechanisms underlying this interaction is important for both understanding these processes in vivo and for deploying ozonolysis chemistry in analytical strategies for lipidomics.

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“…Obviously, this value is beyond the so‐called chemical accuracy of 1 kcal/mol. Employing the DLPNO‐CCSD(T) method, Elm and coworkers investigated the stability of a series of molecular clusters formed in the atmosphere . A maximum absolute deviation of 2.40 kcal/mol from the CCSD(T)‐F12a/VDZ‐F12 reference data was found for the binding energy of the (H 2 SO 4 ) 2 (NH 3 ) 2 cluster, even at the DLPNO‐CCSD(T)/def2‐QZVPP level of theory .…”

Section: Introductionmentioning

confidence: 99%

Toward a less costly but accurate calculation of the CCSD(T)/CBS noncovalent interaction energy

et al. 2020

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The popular method of calculating the noncovalent interaction energies at the coupled-cluster single-, double-, and perturbative triple-excitations [CCSD(T)] theory level in the complete basis set (CBS) limit was to add a CCSD(T) correction term to the CBS second-order Møller-Plesset perturbation theory (MP2). The CCSD(T) correction term is the difference between the CCSD(T) and MP2 interaction energies evaluated in a medium basis set. However, the CCSD(T) calculations with the medium basis sets are still very expensive for systems with more than 30 atoms. Comparatively, the domain-based local pair natural orbital coupled-cluster method [DLPNO-CCSD(T)] can be applied to large systems with over 1,000 atoms. Considering both the computational accuracy and efficiency, in this work, we propose a new scheme to calculate the CCSD(T)/CBS interaction energies. In this scheme, the MP2/CBS term keeps intact and the CCSD(T) correction term is replaced by a DLPNO-CCSD (T) correction term which is the difference between the DLPNO-CCSD(T) and DLPNO-MP2 interaction energies evaluated in a medium basis set. The interaction energies of the noncovalent systems in the S22, HSG, HBC6, NBC10, and S66 databases were recalculated employing this new scheme. The consistent and tight settings of the truncation parameters for DLPNO-CCSD(T) and DLPNO-MP2 in this noncanonical CCSD(T)/CBS calculations lead to the maximum absolute deviation and root-mean-square deviation from the canonical CCSD(T)/CBS interaction energies of less than or equal to 0.28 kcal/mol and 0.09 kcal/mol, respectively. The high accuracy and low cost of this new computational scheme make it an excellent candidate for the study of large noncovalent systems.

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Atmospheric chemistry of iodine anions: elementary reactions of I⁻, IO⁻, and IO₂⁻ with ozone studied in the gas-phase at 300 K using an ion trap

Abstract: Using a radio-frequency ion trap to study ion–molecule reactions under isolated conditions, we report a direct experimental determination of reaction rate constants for the sequential oxidation of iodine anions by ozone at room temperature (300 K).

Cited by 23 publications

References 51 publications

Iodide CIMS and <i>m</i>∕<i>z</i> 62: the detection of HNO<sub>3</sub> as NO<sub>3</sub><sup>−</sup> in the presence of PAN, peroxyacetic acid and ozone

Iodide CIMS and <i>m</i>∕<i>z</i> 62: the detection of HNO<sub>3</sub> as NO<sub>3</sub><sup>−</sup> in the presence of PAN, peroxyacetic acid and ozone

Reaction of ionised steryl esters with ozone in the gas phase

Toward a less costly but accurate calculation of the CCSD(T)/CBS noncovalent interaction energy

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Atmospheric chemistry of iodine anions: elementary reactions of I−, IO−, and IO2− with ozone studied in the gas-phase at 300 K using an ion trap

Abstract: Using a radio-frequency ion trap to study ion–molecule reactions under isolated conditions, we report a direct experimental determination of reaction rate constants for the sequential oxidation of iodine anions by ozone at room temperature (300 K).

Cited by 23 publications

References 51 publications

Iodide CIMS and &lt;i&gt;m&lt;/i&gt;∕&lt;i&gt;z&lt;/i&gt; 62: the detection of HNO&lt;sub&gt;3&lt;/sub&gt; as NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; in the presence of PAN, peroxyacetic acid and ozone

Iodide CIMS and &lt;i&gt;m&lt;/i&gt;∕&lt;i&gt;z&lt;/i&gt; 62: the detection of HNO&lt;sub&gt;3&lt;/sub&gt; as NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; in the presence of PAN, peroxyacetic acid and ozone

Reaction of ionised steryl esters with ozone in the gas phase

Toward a less costly but accurate calculation of the CCSD(T)/CBS noncovalent interaction energy

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Product

Resources

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Atmospheric chemistry of iodine anions: elementary reactions of I⁻, IO⁻, and IO₂⁻ with ozone studied in the gas-phase at 300 K using an ion trap

Iodide CIMS and <i>m</i>∕<i>z</i> 62: the detection of HNO<sub>3</sub> as NO<sub>3</sub><sup>−</sup> in the presence of PAN, peroxyacetic acid and ozone

Iodide CIMS and <i>m</i>∕<i>z</i> 62: the detection of HNO<sub>3</sub> as NO<sub>3</sub><sup>−</sup> in the presence of PAN, peroxyacetic acid and ozone