Oriented Thiocyanate Anions at the Air−Electrolyte Interface and Its Implications on Interfacial Water - A Vibrational Sum Frequency Spectroscopy Study

2007 ◽  
Vol 111 (12) ◽  
pp. 4484-4486 ◽  
Author(s):  
P. Viswanath ◽  
H. Motschmann
Keyword(s):  
Interfacial Water ◽  
Spectroscopy Study ◽  
Sum Frequency ◽  
Electrolyte Interface ◽  
Sum Frequency Spectroscopy ◽  
Vibrational Sum Frequency Spectroscopy

scholarly journals Experimentally probing the libration of interfacial water: the rotational potential of water is stiffer at the air/water interface than in bulk liquid

2016 ◽  
Vol 18 (27) ◽  
pp. 18424-18430 ◽  
Author(s):  
Yujin Tong ◽  
Tobias Kampfrath ◽  
R. Kramer Campen
Keyword(s):  
Liquid Water ◽  
Bulk Liquid ◽  
Interfacial Water ◽  
Water Interface ◽  
Sum Frequency ◽  
Sum Frequency Spectroscopy ◽  
Air Water Interface ◽  
Vibrational Sum Frequency Spectroscopy

Vibrational sum frequency spectroscopy measurements reveal that the libration frequency of interfacial water is significantly higher than bulk liquid water, suggesting that water's rotational potential stiffens on moving from the bulk liquid to the air/water interface.

scholarly journals Structure of the Ethylammonium Nitrate Surface: An X-ray Reflectivity and Vibrational Sum Frequency Spectroscopy Study

Langmuir ◽  
2010 ◽  
Vol 26 (11) ◽  
pp. 8282-8288 ◽  
Author(s):  
Petru Niga ◽  
Deborah Wakeham ◽  
Andrew Nelson ◽  
Gregory G. Warr ◽  
Mark Rutland ◽  
...  
Keyword(s):  
Spectroscopy Study ◽  
X Ray ◽  
Sum Frequency ◽  
Sum Frequency Spectroscopy ◽  
Ethylammonium Nitrate ◽  
Vibrational Sum Frequency Spectroscopy

scholarly journals Structure of the Silica/Divalent Electrolyte Interface: Molecular Insight into Charge Inversion with Increasing pH

2020 ◽  
Author(s):  
Mokhtar Rashwan ◽  
Benjamin Rehl ◽  
Adrien Sthoer ◽  
Akemi Darlington ◽  
Md. Shafiul Azam ◽  
...  
Keyword(s):  
Calcium Hydroxide ◽  
Spectral Feature ◽  
Streaming Potential ◽  
Fused Silica ◽  
Interfacial Water ◽  
Sum Frequency ◽  
Colloidal Chemistry ◽  
Water Signal ◽  
Sum Frequency Spectroscopy ◽  
Vibrational Sum Frequency Spectroscopy

The molecular origin of overcharging at mineral oxide surfaces remains a cause of contention within the geochemistry, physics, and colloidal chemistry communities owing to competing “chemical” vs “physical” interpretations. Here, we combine vibrational sum frequency spectroscopy and streaming potential measurements to obtain molecular and macroscopic insights into the pH-dependent interactions of calcium ions with a fused silica surface. In 100 mM CaCl<sub>2</sub> electrolyte, we observe evidence of charge neutralization at pH~10.5, as deducted from a minimum in the interfacial water signal. Concurrently, adsorption of calcium hydroxide cations is inferred from the appearance of a spectral feature at ~3610 cm<sup>-1</sup>. However, the interfacial water signal increases at higher pH, while adsorbed calcium hydroxide appears to remain constant, indicating that overcharging results from hydrated Ca<sup>2+</sup> ions present within the Stern layer. These findings suggest that both specific adsorption of hydrolyzed ions and ion-ion correlations of hydrated ions govern silica overcharging with increasing pH.

scholarly journals Structure of the Silica/Divalent Electrolyte Interface: Molecular Insight into Charge Inversion with Increasing pH

2020 ◽  
Author(s):  
Mokhtar Rashwan ◽  
Benjamin Rehl ◽  
Adrien Sthoer ◽  
Akemi Darlington ◽  
Md. Shafiul Azam ◽  
...  
Keyword(s):  
Calcium Hydroxide ◽  
Spectral Feature ◽  
Streaming Potential ◽  
Fused Silica ◽  
Interfacial Water ◽  
Sum Frequency ◽  
Colloidal Chemistry ◽  
Water Signal ◽  
Sum Frequency Spectroscopy ◽  
Vibrational Sum Frequency Spectroscopy

The molecular origin of overcharging at mineral oxide surfaces remains a cause of contention within the geochemistry, physics, and colloidal chemistry communities owing to competing “chemical” vs “physical” interpretations. Here, we combine vibrational sum frequency spectroscopy and streaming potential measurements to obtain molecular and macroscopic insights into the pH-dependent interactions of calcium ions with a fused silica surface. In 100 mM CaCl<sub>2</sub> electrolyte, we observe evidence of charge neutralization at pH~10.5, as deducted from a minimum in the interfacial water signal. Concurrently, adsorption of calcium hydroxide cations is inferred from the appearance of a spectral feature at ~3610 cm<sup>-1</sup>. However, the interfacial water signal increases at higher pH, while adsorbed calcium hydroxide appears to remain constant, indicating that overcharging results from hydrated Ca<sup>2+</sup> ions present within the Stern layer. These findings suggest that both specific adsorption of hydrolyzed ions and ion-ion correlations of hydrated ions govern silica overcharging with increasing pH.

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