Cryogenic ion trap vibrational spectroscopy of the microhydrated sulfate dianions SO42−(H2O)3−8

Knorke, Harald; Li, Yong; Warneke, Jonas; Liu, Zhongfan; Asmis, Knut R.

doi:10.1039/d0cp04386a

Cited by 6 publications

(4 citation statements)

References 69 publications

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“…16 , and, unlike the previous cases, the signal depends on the cation identity. Because the spectral shape reports on the hydrogen-bonding connectivity around the sulfate 48 , 49 , this result suggests that the observed difference is due to the formation of (solvent-separated) ion pairs in MgSO 4 (ref. 50 ).…”

Section: Resultsmentioning

confidence: 99%

Surface stratification determines the interfacial water structure of simple electrolyte solutions

Litman,

Chiang,

Seki

et al. 2024

Nat. Chem.

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The distribution of ions at the air/water interface plays a decisive role in many natural processes. Several studies have reported that larger ions tend to be surface-active, implying ions are located on top of the water surface, thereby inducing electric fields that determine the interfacial water structure. Here we challenge this view by combining surface-specific heterodyne-detected vibrational sum-frequency generation with neural network-assisted ab initio molecular dynamics simulations. Our results show that ions in typical electrolyte solutions are, in fact, located in a subsurface region, leading to a stratification of such interfaces into two distinctive water layers. The outermost surface is ion-depleted, and the subsurface layer is ion-enriched. This surface stratification is a key element in explaining the ion-induced water reorganization at the outermost air/water interface.

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Section: Resultsmentioning

confidence: 99%

Surface stratification determines the interfacial water structure of simple electrolyte solutions

Litman,

Chiang,

Seki

et al. 2024

Nat. Chem.

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“…We note that vibrational frequencies of bridging hydrogens are often strongly affected by anharmonic effects and deviate from the calculated harmonic frequencies. 64,65 Therefore, AIMD simulations were performed to account for anharmonic effects. They indicate that instead of a sharp intense band, a broader feature between 2000-2200 cm À1 should be present in the spectrum as shown in Fig.…”

Section: Reactions With Cyclohexane and Hexene Isomers (C 6 H 12 )mentioning

confidence: 99%

Binding of saturated and unsaturated C₆-hydrocarbons to the electrophilic anion [B₁₂Br₁₁]⁻: a systematic mechanistic study

Rohdenburg

Knorke

et al. 2022

Phys. Chem. Chem. Phys.

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“…The isolated sulfate ion SO 4 2– has tetrahedral symmetry T d with three degenerate asymmetric stretching modes and the sulfur atom found in an ideal tetrahedral environment of oxygen atoms. Hydration breaks this molecular symmetry and lifts the degeneracy, − giving rise to a broad unstructured line shape. The two spectra display a different maximum absorption strength and slightly different line shapes, as is evident from the difference spectrum Δ A = A (MgSO 4 )– A (Na 2 SO 4 ) shown as a dashed line in Figure c (absorbance A = −log( T ); sample transmission T ).…”

Section: Resultsmentioning

confidence: 99%

Short-Range Cooperative Slow-down of Water Solvation Dynamics Around SO₄^2––Mg²⁺Ion Pairs

et al. 2022

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The presence of ions affects the structure and dynamics of water on a multitude of length and time scales. In this context, pairs of Mg 2+ and SO 4 2− ions in water constitute a prototypical system for which conflicting pictures of hydration geometries and dynamics have been reported. Key issues are the molecular pair and solvation shell geometries, the spatial range of electric interactions, and their impact on solvation dynamics. Here, we introduce asymmetric SO 4 2− stretching vibrations as new and most specific local probes of solvation dynamics that allow to access ion hydration dynamics at the dilute concentration (0.2 M) of a native electrolyte environment. Highly sensitive heterodyne 2D-IR spectroscopy in the fingerprint region of the SO 4 2− ions around 1100 cm −1 reveals a specific slow-down of solvation dynamics for hydrated MgSO 4 and for Na 2 SO 4 in the presence of Mg 2+ ions, which manifests as a retardation of spectral diffusion compared to aqueous Na 2 SO 4 solutions in the absence of Mg 2+ ions. Extensive molecular dynamics and density functional theory QM/MM simulations provide a microscopic view of the observed ultrafast dephasing and hydration dynamics. They suggest a molecular picture where the slow-down of hydration dynamics arises from the structural peculiarities of solvent-shared SO 4 2− −Mg 2+ ion pairs.

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Cryogenic ion trap vibrational spectroscopy of the microhydrated sulfate dianions SO₄²⁻(H₂O)₃₋₈

Abstract: Infrared photodissociation spectra of microhydrated sulfate dianions with three to eight water molecules are presented over a broad spectral range that covers intramolecular solvent and solute modes as well as intermolecular librational modes.

Cited by 6 publications

References 69 publications

Surface stratification determines the interfacial water structure of simple electrolyte solutions

Surface stratification determines the interfacial water structure of simple electrolyte solutions

Binding of saturated and unsaturated C₆-hydrocarbons to the electrophilic anion [B₁₂Br₁₁]⁻: a systematic mechanistic study

Short-Range Cooperative Slow-down of Water Solvation Dynamics Around SO₄^2––Mg²⁺Ion Pairs

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Cryogenic ion trap vibrational spectroscopy of the microhydrated sulfate dianions SO42−(H2O)3−8

Abstract: Infrared photodissociation spectra of microhydrated sulfate dianions with three to eight water molecules are presented over a broad spectral range that covers intramolecular solvent and solute modes as well as intermolecular librational modes.

Cited by 6 publications

References 69 publications

Surface stratification determines the interfacial water structure of simple electrolyte solutions

Surface stratification determines the interfacial water structure of simple electrolyte solutions

Binding of saturated and unsaturated C6-hydrocarbons to the electrophilic anion [B12Br11]−: a systematic mechanistic study

Short-Range Cooperative Slow-down of Water Solvation Dynamics Around SO42––Mg2+Ion Pairs

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Cryogenic ion trap vibrational spectroscopy of the microhydrated sulfate dianions SO₄²⁻(H₂O)₃₋₈

Binding of saturated and unsaturated C₆-hydrocarbons to the electrophilic anion [B₁₂Br₁₁]⁻: a systematic mechanistic study

Short-Range Cooperative Slow-down of Water Solvation Dynamics Around SO₄^2––Mg²⁺Ion Pairs