Cation Effects on Rotational Dynamics of Anions and Water Molecules in Alkali (Li+, Na+, K+, Cs+) Thiocyanate (SCN-) Aqueous Solutions

	Cation Effects on Rotational Dynamics of Anions and Water Molecules in Alkali (Li+, Na+, K+, Cs+) Thiocyanate (SCN-) Aqueous Solutions
	Bian, Hongtao 1; Chen, Hailong 1; Zhang, Qiang 2; Li, Jiebo 1; Wen, Xiewen 1; Zhuang, Wei 2; Zheng, Junrong 1
刊名	journal of physical chemistry b
	2013-07-04
卷号	117 期号:26 页码:7972-7984
英文摘要	waiting time dependent rotational anisotropies of scn- anions and water molecules in alkali thiocyanate (xscn, x = li, na, k, cs) aqueous solutions at various concentrations were measured with ultrafast infrared spectroscopy. it was found that cations can significantly affect the reorientational motions of both water molecules and scn- anions. the dynamics are slower in a solution with a smaller cation. the reorientational time constants follow the order of li+ > na+ > k+ similar or equal to cs+. the changes of rotational time constants of scn- at various concentrations scale almost linearly with the changes of solution viscosity, but those of water molecules do not. in addition, the concentration-dependent amplitudes of dynamical changes are much more significant in the li+ and na+ solutions than those in the k+ and cs+ solutions. further investigations on the systems with the ultrafast vibrational energy exchange method and molecular dynamics simulations provide an explanation for the observations: the observed rotational dynamics are the balanced results of ion clustering and cation/anion/water direct interactions. in all the solutions at high concentrations (>5 m), substantial amounts of ions form clusters. the structural inhomogeneity in the solutions leads to distinct rotational dynamics of water and anions. the strong interactions of li+ and na+ because of their relatively large charge densities with water molecules and scn- anions, in addition to the likely geometric confinements because of ion clustering, substantially slow down the rotations of scn- anions and water molecules inside the ion clusters. the interactions of k+ and cs+ with water or scn- are much weaker. the rotations of water molecules inside ion clusters of k+ and cs+ solutions are not significantly different from those of other water species so that the experimentally observed rotational relaxation dynamics are only slightly affected by the ion concentrations.
WOS标题词	science & technology ; physical sciences
类目[WOS]	chemistry, physical
研究领域[WOS]	chemistry
关键词[WOS]	vibrational-energy transfer ; hydrogen-bond structure ; liquid water ; molten thiocyanates ; hofmeister series ; phase-transition ; salt-solutions ; raman-spectra ; ions ; hydration
收录类别	SCI
语种	英语
WOS记录号	WOS:000321542200014
公开日期	2015-11-10
内容类型	期刊论文
源URL	[http://159.226.238.44/handle/321008/137611]
专题	大连化学物理研究所_中国科学院大连化学物理研究所
作者单位	1.Rice Univ, Dept Chem, Houston, TX 77005 USA 2.Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Mol React Dynam, Dalian 116023, Liaoning, Peoples R China
推荐引用方式 GB/T 7714	Bian, Hongtao,Chen, Hailong,Zhang, Qiang,et al. Cation Effects on Rotational Dynamics of Anions and Water Molecules in Alkali (Li+, Na+, K+, Cs+) Thiocyanate (SCN-) Aqueous Solutions[J]. journal of physical chemistry b,2013,117(26):7972-7984.
APA	Bian, Hongtao.,Chen, Hailong.,Zhang, Qiang.,Li, Jiebo.,Wen, Xiewen.,...&Zheng, Junrong.(2013).Cation Effects on Rotational Dynamics of Anions and Water Molecules in Alkali (Li+, Na+, K+, Cs+) Thiocyanate (SCN-) Aqueous Solutions.journal of physical chemistry b,117(26),7972-7984.
MLA	Bian, Hongtao,et al."Cation Effects on Rotational Dynamics of Anions and Water Molecules in Alkali (Li+, Na+, K+, Cs+) Thiocyanate (SCN-) Aqueous Solutions".journal of physical chemistry b 117.26(2013):7972-7984.