Molecular orientation determined by second-harmonic generation: Self-assembled monolayers

Eisert, F.; Dannenberger, O.; Buck, Manfred

doi:10.1103/physrevb.58.10860

Cited by 55 publications

(60 citation statements)

References 43 publications

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“…They concluded that using the two-layer model without local-field correction gave most satisfactory agreement of the molecular orientation with the results from the NEXAFS and IR spectroscopy measurements. 51 This work is obviously not consistent with the above treatment by Shen et al It was further criticized by Roy on the inconsistency that the SAM film is considered anisotropic for SHG but assumed to be isotropic in terms of its linear optical properties. 57 Roy then outlined a macroscopic phenomenological model that treats linear and nonlinear optics of the anisotropic interface layer in a single framework, which nevertheless requires a minimum of six unknown parameters of the interfacial optical constants even for an uniaxial monolayer in SHG or SFG-VS. 57,58 Thus, Roy concluded that the conventional SHG measurement of phase and intensity may not be enough to determine the orientation of SAM.…”

Section: 25contrasting

confidence: 50%

“…43,44,45,46,47,48,49,50,51,81 Therefore, we shall neglect the image induced dipole term in the followed treatment.…”

Section: 89mentioning

confidence: 99%

“…26,59,60,61 There have been a few experimental and empirical theory studies on the SHG data from the interfacial monolayer, using different parameters of the macroscopic three layer model plus the microscopic local field factors. 43,44,45,46,47,48,49,50,51,62,63,64 In dealing with the macroscopic dielectric constant, generally one of the two bulk phase values were used, reducing the macroscopic problem to the same as the so-called two phase model.…”

Section: 25mentioning

confidence: 99%

“…21,25,41,42,43,44,45,46,47,48,49,50,51,52,53 It has been well demonstrated that in majority cases the calculation of the molecular orientation is quite sensitive to the values used for these two factors. 21,25,42,51,52 In the currently accepted models of the nonlinear optics of interface, 4,34,41,53,54,55 the nonlinear radiation was treated as the result of an infinitesimally thin polarization sheet layer, and as the starting pint a macroscopic dielectric constant was assigned to this thin layer. 4,34,54,55 This model was a natural extension of the original formulation by Bloembergen and Pershan, where a nonlinear plane parallel slab with a finite thickness embedded between two linear dielectrics was the source of the SHG radiation, and where the Maxwell's equations which satisfy the boundary conditions at the two plane interfaces were accurately solved.…”

Section: Introductionmentioning

confidence: 99%

“…They concluded that using the two-layer model without local-field correction gave most satisfactory agreement of the molecular orientation with the results from the NEXAFS and IR spectroscopy measurements. 51 According to Eisert et al, the parameters used to calculate the local field factors in the Eq.13 and the Eq.14 of the pNA [O 2 N-C 6 H 4 -] monolayer in the SHG experiment are: a = 5 to 5.5Å, α aa = α bb = 16.4Å…”

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confidence: 99%

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Microscopic molecular optics theory of surface second harmonic generation and sum-frequency generation spectroscopy based on the discrete dipole lattice model

Dong¹,

Yuan²,

Liu³

et al. 2008

International Reviews in Physical Chemistry

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Two crucial issues in the interface studies with the interface specific nonlinear spectroscopy are on how to describe the macroscopic dielectric constant of the molecularly thin layer and how to calculate the anisotropic two dimensional microscopic local field effect. In the currently accepted models of the nonlinear optics, the nonlinear radiation was treated as the result of an infinitesimally thin polarization sheet layer, and a three layer model was generally employed. The direct consequence of this approach is that an apriori dielectric constant, which still does not have a clear definition, has to be assigned to this polarization layer. Because the Second Harmonic Generation (SHG) and the Sum-Frequency Generation vibrational Spectroscopy (SFG-VS) have been proven as the sensitive probes for interfaces with the submonolayer coverage, the treatment based on the more realistic discrete induced dipole model needs to be developed. Here we show that following the molecular optics theory approach the SHG, as well as the SFG-VS, radiation from the monolayer or submonolayer at an interface can be rigorously treated as the radiation from an induced dipole lattice at the interface. In this approach, the introduction of the polarization sheet is no longer necessary. Therefore, the ambiguity of the unaccounted dielectric constant of the polarization layer is no longer an issue. Moreover, the anisotropic two dimensional microscopic local field factors can be explicitly expressed with the linear polarizability tensors of the interfacial molecules. Based on the planewise dipole sum rule in the molecular monolayer, crucial experimental tests of this microscopic treatment with SHG and SFG-VS are discussed. Many puzzles in the literature of surface SHG and SFG spectroscopy studies can also be understood or resolved in this framework. This new treatment may provide a solid basis for the quantitative analysis in the surface SHG and SFG studies.

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Section: 25contrasting

confidence: 50%

“…43,44,45,46,47,48,49,50,51,81 Therefore, we shall neglect the image induced dipole term in the followed treatment.…”

Section: 89mentioning

confidence: 99%

Section: 25mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…They concluded that using the two-layer model without local-field correction gave most satisfactory agreement of the molecular orientation with the results from the NEXAFS and IR spectroscopy measurements. 51 According to Eisert et al, the parameters used to calculate the local field factors in the Eq.13 and the Eq.14 of the pNA [O 2 N-C 6 H 4 -] monolayer in the SHG experiment are: a = 5 to 5.5Å, α aa = α bb = 16.4Å…”

mentioning

confidence: 99%

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