Quantitative analysis of orientational order in the molecular monolayer by surface second harmonic generation

	Quantitative analysis of orientational order in the molecular monolayer by surface second harmonic generation
	Rao, Y ; Tao, YS ; Wang, HF
刊名	journal of chemical physics
	2003-09-08
卷号	119 期号:10 页码:5226-5236
英文摘要	we have developed a systematic approach to quantitatively determine the orientational order of molecular monolayer based on surface second harmonic generation (shg) measurement. traditionally, the experimentally obtainable orientational parameter d=/ has been used to determine the averaged orientational angle theta with shg. also, it has been widely accepted that without the help from other techniques, shg was insufficient for determination of both the orientational angle theta(0) and its distribution deltatheta. here, we derived an explicit and general functional form, r(theta)=parallel to-c * parallel to(2), which is orientationally dependent and is proportional to the sh intensity measured from the molecular monolayer. we further showed that r(theta) contains the full information of the orientational order of the molecular monolayer, and the orientational parameter d represents only a special case of r(theta). through orientationally sensitive r(theta) and d, both the orientational angle and its distribution could be uniquely and accurately determined from the shg-only measurements in chosen polarization configurations. using this approach, we were able to accurately determine both the orientational angle and its distribution in the langmuir monolayer of a liquid crystal molecule 4(')-n-octyl-4-cyanobiphenyl (8cb) at the air/water interface. with such information, we were not only able to show that the phase transition of 8cb from the gas-liquid coexistence region to liquid region is accompanied with a continuous orientational angular distribution narrowing process, but also for the first time we were able to accurately determine a less than 3degrees tilt angle change of the 8cb chromophore in the whole liquid phase region of the 8cb monolayer. this quantitative approach to orientational analysis of molecular monolayer or multilayer is general for both shg and sum frequency generation, and should lead the way to more quantitative understanding of the orientational order of molecular films per se. (c) 2003 american institute of physics.
WOS标题词	science & technology ; physical sciences
类目[WOS]	physics, atomic, molecular & chemical
研究领域[WOS]	physics
关键词[WOS]	frequency vibrational spectroscopy ; air-water-interface ; self-assembled monolayers ; x-ray-diffraction ; sum-frequency ; langmuir monolayers ; phase-transitions ; liquid interfaces ; angle ; films
收录类别	SCI
语种	英语
WOS记录号	WOS:000184899200025
公开日期	2015-11-10
内容类型	期刊论文
源URL	[http://159.226.238.44/handle/321008/138398]
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.Chinese Acad Sci, Inst Chem, Ctr Mol Sci, State Key Lab Mol React Dynam, Beijing 100080, Peoples R China 2.Chinese Acad Sci, Grad Sch, Beijing 100080, Peoples R China
推荐引用方式 GB/T 7714	Rao, Y,Tao, YS,Wang, HF. Quantitative analysis of orientational order in the molecular monolayer by surface second harmonic generation[J]. journal of chemical physics,2003,119(10):5226-5236.
APA	Rao, Y,Tao, YS,&Wang, HF.(2003).Quantitative analysis of orientational order in the molecular monolayer by surface second harmonic generation.journal of chemical physics,119(10),5226-5236.
MLA	Rao, Y,et al."Quantitative analysis of orientational order in the molecular monolayer by surface second harmonic generation".journal of chemical physics 119.10(2003):5226-5236.