精度在0.1nm的薄层厚度
衬底的光学常数
分子取向
表面质量分布
表面结构形态
快速获取数据功能使观测诸如腐蚀、吸附等过程成为可能,测量不具有破坏性,适合多种样品的测量,即使液-液界面也可以实现。
椭偏仪的应用十分广泛:
Assessment of scaling laws
Ion distribution
Photochemisty
Adsorption isotherms
Corrosion
Characterization of thin films
Glass transition in confined geometries
Determination of optical constants
Swelling experiment
The following chapter presents the basics of ellipsometry and discusses some recent advances. The article covers the formalism and theory used for data analysis as well as instrumentation. The treatment is also designed to familiarize newcomers to this ßeld.
The experimental focus is on adsorption layers at the air-water and oil-water interface.
Selected examples are discussed to illustrate the potential as well as the limits of this technique. The authors hope, that this article contributes to a wider use of this technique in the colloidal physics and chemistry community. Many problems in our ßeld of science
can be tackled with this technique.
The orientation, structure, and energetics of the vapor/acetone-water interface are studied with sum frequency
generation vibrational spectroscopy (SFG-VS). We used the polarization null angle (PNA) method in SFGVS
to accurately determine the interfacial acetone molecule orientation, and we found that the acetone molecule
has its CdO group pointing into bulk phase, one CH3 group pointing up from the bulk, and the other CH3
group pointing into the bulk phase. This well-ordered interface layer induces an antiparallel structure in the
second layer through dimer formation from either dipolar or hydrogen bond interactions. With a double-layer
adsorption model (DAM) and Langmuir isotherm, the adsorption free energies for the first and second layer
are determined as ¢G°ads,1 ) - 1.9 ( 0.2 kcal /mol and ¢G°ads,2 ) - 0.9 ( 0.2 kcal /mol, respectively.
Since ¢G°ads,1 is much larger than the thermal energy kT ) 0.59 kcal /mol, and ¢G°ads,2 is close to kT, the
second layer has to be less ordered. Without either strong dipolar or hydrogen bonding interactions between
the second and the third layer, the third layer should be randomly thermalized as in the bulk liquid. Therefore,
the thickness of the interface is not more than two layers thick. These results are consistent with previous
MD simulations for the vapor/pure acetone interface, and undoubtedly provide direct microscopic structural
evidences and new insight for the understanding of liquid and liquid mixture interfaces. The experimental
techniques and quantitative analysis methodology used for detailed measurement of the liquid mixture interfaces
in this report can also be applied to liquid interfaces, as well as other molecular interfaces in general.
Insoluble monolayers at the air-water interface are exposed to a gas phase containing organic hydrocarbons. The hydrocarbons are partly incorporated within the monolayer which leads to changes
in orientational order and the formation of new phases of different morphology. The transition state resembles features of the air-water and oil-water interface and the control of the hydrocarbon partial
pressure allows continous tuning between both interfaces. The phospholipid D,L-R-dipalmitoylphosphatidylethanolamine,DPPE, and an esterdiol hexadecanoic acid, 2,3-dihydroxypropyl ester, ESD-16, are used as amphiphiles, and pentane, n-hexane, cyclohexane, 2,2-dimethylbutane, n-heptane, n-decane, and n-dodecane are used as hydrocarbons. Both amphiphiles differ in their headgroup size. In DPPE the aliphatic tail determines the packing within the monolayer, but in the case of ESD-16 it is the headgroups.The structural changes are monitiored by surface pressure-area (ð,A) isotherms and imaging ellipsometry.The influence of the chemical nature of the hydrocarbon and the effect of the partial pressure of the
hydrocarbon on the monolayer structure are assessed.
Ellipsometry is a very sensitive measurement technique that uses polarized light to characterize thin films, surfaces,and material microstructure. Usually the polarization of light changes upon reflection. These changes are measured by an ellipsometer and interpreted on the basis of model calculations.
The following chapter presents the basics of ellipsometry and discusses some recent advances. The article covers the formalism and theory used for data analysis as well as instrumentation. The treatment is also designed to familiarize newcomers to this ßeld.
The experimental focus is on adsorption layers at the air-water and oil-water interface.
Selected examples are discussed to illustrate the potential as well as the limits of this technique. The authors hope, that this article contributes to a wider use of this technique in the colloidal physics and chemistry community. Many problems in our ßeld of science
can be tackled with this technique.
The orientation, structure, and energetics of the vapor/acetone-water interface are studied with sum frequency
generation vibrational spectroscopy (SFG-VS). We used the polarization null angle (PNA) method in SFGVS
to accurately determine the interfacial acetone molecule orientation, and we found that the acetone molecule
has its CdO group pointing into bulk phase, one CH3 group pointing up from the bulk, and the other CH3
group pointing into the bulk phase. This well-ordered interface layer induces an antiparallel structure in the
second layer through dimer formation from either dipolar or hydrogen bond interactions. With a double-layer
adsorption model (DAM) and Langmuir isotherm, the adsorption free energies for the first and second layer
are determined as ¢G°ads,1 ) - 1.9 ( 0.2 kcal /mol and ¢G°ads,2 ) - 0.9 ( 0.2 kcal /mol, respectively.
Since ¢G°ads,1 is much larger than the thermal energy kT ) 0.59 kcal /mol, and ¢G°ads,2 is close to kT, the
second layer has to be less ordered. Without either strong dipolar or hydrogen bonding interactions between
the second and the third layer, the third layer should be randomly thermalized as in the bulk liquid. Therefore,
the thickness of the interface is not more than two layers thick. These results are consistent with previous
MD simulations for the vapor/pure acetone interface, and undoubtedly provide direct microscopic structural
evidences and new insight for the understanding of liquid and liquid mixture interfaces. The experimental
techniques and quantitative analysis methodology used for detailed measurement of the liquid mixture interfaces
in this report can also be applied to liquid interfaces, as well as other molecular interfaces in general.
Insoluble monolayers at the air-water interface are exposed to a gas phase containing organic hydrocarbons. The hydrocarbons are partly incorporated within the monolayer which leads to changes
in orientational order and the formation of new phases of different morphology. The transition state resembles features of the air-water and oil-water interface and the control of the hydrocarbon partial
pressure allows continous tuning between both interfaces. The phospholipid D,L-R-dipalmitoylphosphatidylethanolamine,DPPE, and an esterdiol hexadecanoic acid, 2,3-dihydroxypropyl ester, ESD-16, are used as amphiphiles, and pentane, n-hexane, cyclohexane, 2,2-dimethylbutane, n-heptane, n-decane, and n-dodecane are used as hydrocarbons. Both amphiphiles differ in their headgroup size. In DPPE the aliphatic tail determines the packing within the monolayer, but in the case of ESD-16 it is the headgroups.The structural changes are monitiored by surface pressure-area (ð,A) isotherms and imaging ellipsometry.The influence of the chemical nature of the hydrocarbon and the effect of the partial pressure of the
hydrocarbon on the monolayer structure are assessed.
True phase-matched second-harmonic generation in a waveguide of crosslinkable ferroelectric liquid crystals is demonstrated. These materials allow the formation of macroscopically polar
structures whose order can be frozen by photopolymerization. Homeotropic alignment was chosen which offers decisive advantages compared to other geometries. All parameters contributing to the
conversion efficiency are maximized by deliberately controlling the supramolecular arrangement.The system has the potential to achieve practical level of performances as a frequency doubler for low power laser-diodes.
Ellipsometry is a very sensitive measurement technique that uses polarized light to characterize thin films, surfaces,and material microstructure. Usually the polarization of light changes upon reflection. These changes are measured by an ellipsometer and interpreted on the basis of model calculations.