Infrared Spectroscopy of Hydrated Bisulfate Anion Clusters: HSO4¯(H2O)1–16

Yacovitch, Tara I.; Wende, Torsten; Jiang, Ling; Heine, Nadja; Meijer, Gerard; Neumark, Daniel M.; Asmis, Knut R.

doi:10.1021/jz200917f

Cited by 90 publications

(139 citation statements)

References 43 publications

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“…The single free OH stretch is clearly evident at the high energy end of the spectrum at 3616 cm −1 , as are the NH stretching bands at 3340 and 3410 cm −1 , often observed for the symmetric and asymmetric stretches of an −NH 2 group. 49 The bands below 1350 cm −1 are typical for bisulfate ions embedded in H-bonded networks, 41 but the exact assignments are not obvious based on comparison with other systems. We therefore turned to the reported harmonic structures for the three candidate structures reported previously.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Vibrational Spectra and Fragmentation Pathways of Size-Selected, D₂-Tagged Ammonium/Methylammonium Bisulfate Clusters

Johnson

2013

J. Phys. Chem. A

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Particles consisting of ammonia and sulfuric acid are widely regarded as seeds for atmospheric aerosol nucleation, and incorporation of alkylamines has been suggested to substantially accelerate their growth. Despite significant efforts, little direct experimental evidence exists for the structures and chemical processes underlying multicomponent particle nucleation. Here we are concerned with the positively charged clusters of ammonia and sulfuric acid with compositions H(+)(NH3)m(H2SO4)n (2 ≤ m ≤ 5, 1 ≤ n ≤ 4), for which equilibrium geometry structures have been reported in recent computational searches. The computed harmonic vibrational spectra of such minimum energy structures can be directly compared with the experimental spectra of each cluster composition isolated in the laboratory using cryogenic ion chemistry methods. We present one-photon (i.e., linear) infrared action spectra of the isolated gas phase ions cryogenically cooled to 10 K, allowing us to resolve the characteristic vibrational signatures of these clusters. Because the available calculated spectra for different structural candidates have been obtained using different levels of theory, we reoptimized the previously reported structures with several common electronic structure methods and find excellent agreement can be achieved for the (m = 3, n = 2) cluster using CAM-B3LYP with only minor structural differences from the previously identified geometries. At the larger sizes, the experimental spectra strongly resemble that observed for 180 nm ammonium bisulfate particles. The characteristic ammonium- and bisulfate-localized bands are clearly evident at all sizes studied, indicating that the cluster structures are indeed ionic in nature. With the likely (3,2) structure in hand, we then explore the spectral and structural changes caused when methylamine is substituted for ammonia. This process is found to occur with minimal perturbation of the unsubstituted cluster. The thermal decomposition pathways were also evaluated using multiple-photon induced dissociation and are, in all cases, dominated (>100:1) by evaporation of a neutral ammonia molecule rather than methylamine. Spectra obtained for the product cluster ions resulting from this evaporation are consistent with the formation of a single hydrogen bond between two neighboring bisulfate ions, partially regenerating a sulfuric acid molecule. These results provide critical experimental benchmarks for ongoing theoretical efforts to understand the early stages of aerosol growth.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Vibrational Spectra and Fragmentation Pathways of Size-Selected, D₂-Tagged Ammonium/Methylammonium Bisulfate Clusters

Johnson

2013

J. Phys. Chem. A

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“…We note that this is an IRMPD spectrum, and as such the spectrum may be complicated by the transparency effect if oscillator strength at the one-photon level is suppressed after absorption of the first photon. 12,13,65 The water binding energies on the bare Mg 2+ (H 2 O) n=3=10 clusters have been reported to fall rapidly after completion of the first hydration shell at n = 6, converging on a value around 4000 cm −1 by n = 10, which is approaching the photon energy of the free OH stretching bands in question. 56,66−70 Although not definitive because of these experimental limitations, the data are most consistent with the 11th water molecule starting the onset of the second hydration shell around one of the Mg 2+ ions, which is consistent with the expectation that this form corresponds to the global minimum.…”

Section: Observation Of Symmetrical Hydration Inmentioning

confidence: 99%

Vibrational Signatures of Solvent-Mediated Deformation of the Ternary Core Ion in Size-Selected [MgSO₄Mg(H₂O)_n=4–11]²⁺ Clusters

et al. 2015

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Elucidation of the molecular-level mechanics underlying the dissolution of salts is one of the long-standing, fundamental problems in electrolyte chemistry. Here we follow the incremental structural changes that occur when water molecules are sequentially added to the ternary [MgSO4Mg](2+) ionic assembly using cryogenic vibrational predissociation spectroscopy of the cold, mass-selected [MgSO4Mg(H2O)n=4-11](2+) cluster ions. Although the bare [MgSO4Mg](2+) ion could not be prepared experimentally, its calculated minimum energy structure corresponds to a configuration where the two Mg(2+) ions attach on opposite sides of the central SO4(2-) ion in a bifurcated fashion to yield a D2d symmetry arrangement. Analysis of the observed spectral patterns indicate that water molecules preferentially attach to the flanking Mg(2+) ions for the n ≤ 7 hydrates, which results in an incremental weakening of the interaction between the ions. Water molecules begin to interact with the sequestered SO4(2-) anion promptly at n = 8, where changes in the band pattern clearly demonstrate that the intrinsic bifurcated binding motif among the ions evolves into quasilinear Mg(2+)-O-S arrangements as water molecules H-bond to the now free SO groups. Although condensed-phase MgSO4 occurs with a stable hexahydrate in which water molecules lie between the ion pairs, addition of a sixth water molecule to one of the Mg(2+) ions in the n = 11 cluster occurs with the onset of the second hydration shell such that the cation remains coordinated to one of the SO4(2-) oxygen atoms.

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“…The value of 641 cm À 1 for Fe-O symmetrical stretch proves the crystallinity of the sample and the small length of the unit cell. The band situated at 1663 cm À 1 is due to bending vibration of water molecules, whereas the band at 1794 cm À 1 corresponds to a combination band composed of contributions from the asymmetric stretch of carbonate groups [29] and water bending modes, found also in case of bicarbonate anion clusters [30] and hydrated bisulfated anion clusters [31].…”

Section: Ft-ir and Uv-vis Diffuse Reflectance Measurementsmentioning

confidence: 98%

A facile hydrothermal route for the synthesis of α-FeOOH with controlled morphology

Rădiţoiu

Diamandescu

Corobea

et al. 2012

Journal of Crystal Growth

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Infrared Spectroscopy of Hydrated Bisulfate Anion Clusters: HSO₄¯(H₂O)_1–16

Cited by 90 publications

References 43 publications

Vibrational Spectra and Fragmentation Pathways of Size-Selected, D₂-Tagged Ammonium/Methylammonium Bisulfate Clusters

Vibrational Spectra and Fragmentation Pathways of Size-Selected, D₂-Tagged Ammonium/Methylammonium Bisulfate Clusters

Vibrational Signatures of Solvent-Mediated Deformation of the Ternary Core Ion in Size-Selected [MgSO₄Mg(H₂O)_n=4–11]²⁺ Clusters

A facile hydrothermal route for the synthesis of α-FeOOH with controlled morphology

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Infrared Spectroscopy of Hydrated Bisulfate Anion Clusters: HSO4¯(H2O)1–16

Cited by 90 publications

References 43 publications

Vibrational Spectra and Fragmentation Pathways of Size-Selected, D2-Tagged Ammonium/Methylammonium Bisulfate Clusters

Vibrational Spectra and Fragmentation Pathways of Size-Selected, D2-Tagged Ammonium/Methylammonium Bisulfate Clusters

Vibrational Signatures of Solvent-Mediated Deformation of the Ternary Core Ion in Size-Selected [MgSO4Mg(H2O)n=4–11]2+ Clusters

A facile hydrothermal route for the synthesis of α-FeOOH with controlled morphology

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Infrared Spectroscopy of Hydrated Bisulfate Anion Clusters: HSO₄¯(H₂O)_1–16

Vibrational Spectra and Fragmentation Pathways of Size-Selected, D₂-Tagged Ammonium/Methylammonium Bisulfate Clusters

Vibrational Spectra and Fragmentation Pathways of Size-Selected, D₂-Tagged Ammonium/Methylammonium Bisulfate Clusters

Vibrational Signatures of Solvent-Mediated Deformation of the Ternary Core Ion in Size-Selected [MgSO₄Mg(H₂O)_n=4–11]²⁺ Clusters