Monolayer vibrational spectroscopy by infrared-visible sum generation at metal and semiconductor surfaces

Harris, A. L.; Chidsey, Christopher E. D.; Levinos, N. J.; Loiacono, D. N.

doi:10.1016/0009-2614(87)85037-6

Cited by 203 publications

(149 citation statements)

References 12 publications

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“…2͑a͒, the spectra at n = 70 and 80 mainly show two weak dips around 2878 and 2944 cm −1 , resembling those at n = 4. Note that the symmetric ͑d + ͒ and asymmetric ͑d − ͒ C-H stretching modes of the methylene ͑CH 2 ͒ groups, arising from the gauche defects in the layers, [14][15][16][17] can also be observed around 2850 and 2920 cm −1 , respectively. These film defects sometimes appear in the LB multilayers during film deposition and their extent is not experimentally controllable.…”

Section: A Monolayer/dielectric Film/gold Substrate Systemmentioning

confidence: 99%

“…The counterpropagating geometry was frequently adopted 6,15,[34][35][36] in the initial development of SFG. The counterpropagating system has the advantage that the angle between the reflected SFG light and the reflected visible pump beam is greater than that for the copropagating geometry, which reduces the influence of the scattered visible light and aids more efficient collection of the SFG light.…”

Section: Effect Of Incident Beam Geometrymentioning

confidence: 99%

“…The counterpropagating system has the advantage that the angle between the reflected SFG light and the reflected visible pump beam is greater than that for the copropagating geometry, which reduces the influence of the scattered visible light and aids more efficient collection of the SFG light. 6,15,[34][35][36] This geometry is also used in pumpprobe experiments since it can use the experimental space in an efficient way. 34 Recently, the copropagating geometry has become more widely used due to its simplicity for alignment and maintenance.…”

Section: Effect Of Incident Beam Geometrymentioning

confidence: 99%

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Interference effects in the sum frequency generation spectra of thin organic films. II: Applications to different thin-film systems

Tong

Zhao

et al. 2010

The Journal of Chemical Physics

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In this paper, the results of the modeling calculations carried out for predicting the interference effects expected in the sum frequency generation ͑SFG͒ spectra of a specific thin-layer system, described in the accompanying paper, are tested by comparing them with the experimental spectra obtained for a real thin-layer film comprising an organic monolayer/variable thickness dielectric layer/gold substrate. In this system, two contributions to the SFG spectra arise, a resonant contribution from the organic film and a nonresonant contribution from the gold substrate. The modeling calculations are in excellent agreement with the experimental spectra over a wide range of thicknesses and for different polarization combinations. The introduction of another resonant monolayer adjacent to the gold substrate and with the molecules having a reverse orientation has a significant affect on the spectral shapes which is predicted. If a dielectric substrate such as CaF 2 is used instead of a gold substrate, only the spectral intensities vary with the film thickness but not the spectral shapes. The counterpropagating beam geometry will change both the thickness dependent spectral shapes and the intensity of different vibrational modes in comparison with a copropagating geometry. The influences of these experimental factors, i.e., the molecular orientational structure in the thin film, the nature of the substrate, and the selected incident beam geometry, on the experimental SFG spectra are quantitatively predicted by the calculations. The thickness effects on the signals from a SFG active monolayer contained in a thin liquid-layer cell of the type frequently used for in situ electrochemical measurements is also discussed. The modeling calculation is also valid for application to other thin-film systems comprising more than two resonant SFG active interfaces by appropriate choice of optical geometries and relevant optical properties.

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Section: A Monolayer/dielectric Film/gold Substrate Systemmentioning

confidence: 99%

Section: Effect Of Incident Beam Geometrymentioning

confidence: 99%

Section: Effect Of Incident Beam Geometrymentioning

confidence: 99%

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Interference effects in the sum frequency generation spectra of thin organic films. II: Applications to different thin-film systems

Tong

Zhao

et al. 2010

The Journal of Chemical Physics

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“…Since the first demonstrations of vibrational sum frequency generation, published in 1987 by Guyot-Sionnest et al [8] and Harris et al [9] many experiments have been performed using this method. Thanks to the work of many researchers the method has evolved from an exotic tool, used by only a few devoted laser experts to study model systems, to a tool that can be used by many for a diverse number of applications.…”

mentioning

confidence: 99%

Nonlinear Optical Spectroscopy of Soft Matter Interfaces

Roke

2009

ChemPhysChem

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Molecular interfacial properties of colloidal soft matter systems (for example vesicle fusion, or particle synthesis) can be investigated without the need of planar model systems or fluorescent labelling. Exclusively observing chemical properties and changes in a molecular layer of a few molecular dimensions thick around a small particle adds a new dimension to the field of surface science (see figure). Soft matter consists of complex molecules that can undergo drastic structural transformations under mild changes of chemical and physical conditions. Since a wide variety of chemical, physical and biological processes occur at soft matter interfaces, they can exhibit complex behavior. This is even more so for interfaces of colloidal soft matter since the relative amount of interface material increases by orders of magnitude. Herein, we focus on new developments that enable us to obtain detailed molecular structural changes in the topmost molecular layers of soft matter interfaces composed of complex bio‐molecules. In particular, the possibilities to probe interfaces of colloidal soft matter systems are discussed.

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“…The argument of symmetry breaking at interfaces, which yields the interface specificity of MSHG, should equally apply to magnetization-induced sumfrequency generation ͑MSFG͒. Though SFG has been used for surface studies for more than a decade, 12,13 nothing is known on the magnetic properties of SFG. Compared to MSHG, MSFG would allow for much more spectroscopic opportunities, for example to probe magnetic excitations at surfaces and interfaces.…”

mentioning

confidence: 99%

Observation of strong magnetic effects in visible-infrared sum frequency generation from magnetic structures

et al. 2000

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We have observed very strong magnetization-induced changes of the infrared-visible sum-frequency generation ͑SFG͒ intensity from thin magnetic films using a free electron laser as a tunable infrared source. With the help of a magnetic grating a clear resonance is observed due to the excitation of surface plasmonpolaritons. The magnetization dependence of this resonance opens the way for nonlinear magneto-optical SFG studies of magnetic surface excitations.In recent years, magnetization-sensitive second harmonic generation ͑MSHG͒ has been developed into a valuable method to study magnetic surfaces and multilayers. [1][2][3][4][5][6] This nonlinear magneto-optical technique combines the convenience of an optical technique with intrinsic surface/interface sensitivity 3,4 and strongly enhanced magneto-optical effects. 5 For example, MSHG allowed to detect enhanced magnetic moments at atomic steps, 7 to correlate interface roughness with interface anisotropy 8 and to obtain very high contrast domain images for thin films. 9 In addition, nonlinear magneto-optical effects have been discovered. 10,11 Second harmonic generation is just a degenerate case of the general nonlinear optical process of three-wave mixing, 1 ϩ 2 ϭ 3 . The argument of symmetry breaking at interfaces, which yields the interface specificity of MSHG, should equally apply to magnetization-induced sumfrequency generation ͑MSFG͒. Though SFG has been used for surface studies for more than a decade, 12,13 nothing is known on the magnetic properties of SFG. Compared to MSHG, MSFG would allow for much more spectroscopic opportunities, for example to probe magnetic excitations at surfaces and interfaces.In this paper we demonstrate that such a generalization can indeed be carried out and leads to very strong (Ͼ50%) effects on ultrathin films of iron on a GaAs͑001͒ single crystal surface as well as on sandwiched Pt/CoNi/Pt layers and nanostructure arrays. By syncronizing the output of a frequency doubled Nd:YLF laser with the tunable IR output of a free electron laser we obtained an SFG signal that was strongly dependent on the magnetization. On an array of magnetic lines ͑magnetic grating͒ a clear resonance was observed as a function of the infrared wavelength, which is an indication of the excitation of surface plasmon-polariton modes. The dependence of this resonant feature on the magnetization direction suggests a considerable interaction of these modes with the magnetization.The nonlinear optical polarization induced in a sample by two incident optical fields can be written aswhere s f g , ir , and vis are the frequencies of the SFG, infrared and visible beams, respectively, and i jk (2) is the second-order nonlinear optical susceptibility tensor similar as used for the description of MSHG. 1 Both SHG and SFG are described by a third rank tensor that vanishes in media with inversion symmetry, yielding the sensitivity of both SHG and SFG for symmetry breaking interfaces. In the same way one can also immediately derive the nonzero i jk (2) elements that a...

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Monolayer vibrational spectroscopy by infrared-visible sum generation at metal and semiconductor surfaces

Cited by 203 publications

References 12 publications

Interference effects in the sum frequency generation spectra of thin organic films. II: Applications to different thin-film systems

Interference effects in the sum frequency generation spectra of thin organic films. II: Applications to different thin-film systems

Nonlinear Optical Spectroscopy of Soft Matter Interfaces

Observation of strong magnetic effects in visible-infrared sum frequency generation from magnetic structures

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