Spectroscopic investigation on intermolecular and intramolecular motions of concentrated aqueous KSCN solution

• Published in: Chemical physics Vol. 407; pp. 46 - 52
• Main Authors: Lu, Rong, Wang, Wei, Sun, Qinfang, Yu, Anchi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2012
• Subjects: Aqueous KSCN solution; Hydrogen bond; Intermolecular vibration; Intramolecular vibration; OHD-RIKES; Raman spectroscopy; OHD-RIKES; Intramolecular vibration; Aqueous KSCN solution; Raman spectroscopy; Intermolecular vibration; Hydrogen bond
• ISSN: 0301-0104
• DOI: 10.1016/j.chemphys.2012.08.025

[Display omitted] ► Intermolecular and intramolecular motions of aqueous KSCN solution are studied. ► Concentrated aqueous KSCN solutions present large anisotropic hyperpolarizability. ► The 45cm−1 vibration in aqueous KSCN solution is the librational motion of SCN−. ► SCN− severely distorts intermolecular hydrogen bond of water. Both intermolecular and intramolecular motions of concentrated aqueous KSCN solution were investigated by means of femtosecond optical heterodyne-detected Raman induced Kerr effect spectroscopy (OHD-RIKES) and Raman spectroscopy. We found that all concentrated aqueous KSCN solutions present significantly large anisotropic hyperpolarizabilities in their femtosecond OHD-RIKES measurements, which is attributed to a 45cm−1 librational motion of SCN−. We also found that the weakening of the 170cm−1 stretching motion of water intermolecular hydrogen bond (HB) by 0.10m (molality) KSCN is equivalent to that by 4.00m KBr in aqueous solution, which implies SCN− strongly distort the HB network of water. Besides, we found that the rotational relaxation time constant of SCN− increases with the increase of KSCN concentration in aqueous solution, which is correlated with the corresponding viscosity of respective aqueous KSCN solution.