Sum Frequency Generation Studies of Surfaces of High-Surface-Area Powdered Materials

Yeganeh, M. S.; Dougal, S. M.; Silbernagel, B. G.

doi:10.1021/la0518905

Cited by 44 publications

(53 citation statements)

References 17 publications

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“…Consequently, the SFG field may be different on opposite nanoparticle sides, breaking the inversion symmetry. 22 Assuming that inversion symmetry holds, the top nanoparticle surface will be the dominant contributor to the SFG signal and the pyridinium cation will be oriented in an upright conformation, as shown schematically in Figure 4.…”

Section: Surface Coverage σ (Molecules/cmmentioning

confidence: 99%

Sum Frequency Generation Vibrational Spectroscopy of Pyridine Hydrogenation on Platinum Nanoparticles

2008

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Pyridine hydrogenation in the presence of a surface monolayer consisting of cubic Pt nanoparticles stabilized by tetradecyltrimethylammonium bromide (TTAB) was investigated by sum frequency generation (SFG) vibrational spectroscopy using total internal reflection (TIR) geometry. TIR-SFG spectra analysis revealed that a pyridinium cation (C 5 H 5 NH + ) forms during pyridine hydrogenation on the Pt nanoparticle surface, and the NH group in the C 5 H 5 NH + cation becomes more hydrogen bound with the increase of the temperature. In addition, the surface coverage of the cation decreases with the increase of the temperature. An important contribution of this study is the in situ identification of reaction intermediates adsorbed on the Pt nanoparticle monolayer during pyridine hydrogenation.

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Section: Surface Coverage σ (Molecules/cmmentioning

confidence: 99%

Sum Frequency Generation Vibrational Spectroscopy of Pyridine Hydrogenation on Platinum Nanoparticles

2008

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“…Recent studies have demonstrated that SFG is a powerful and information-rich probe of nanostructured surfaces [193][194][195], and surface behaviors with nanoparticles [159,[196][197][198][199][200]. In the following sections, recent advancements that explore the utility of SFG as a powerful and unique technique to study surfaces/interfaces containing nanoparticles will be covered.…”

Section: Sfg Studies At the Nano-bio Interfacementioning

confidence: 99%

“…Later, Rupprechter used SFG to study the CO molecules adsorbed on Pd or Pt nanoparticles at controlled pressure and temperature [202,203]. Yeganeh et al [197] demonstrated that the total internal reflection (TIR) configuration reduces destructive interference associated with non-linear optical spectroscopy of small particles making SFG studies of small objects possible. In a similar way, SFG spectroscopy in total internal reflection geometry was successfully applied to study the adsorption and oxidation of CO on monolayer films of platinum cubic nanoparticles [198].…”

Section: Sfg Studies At the Nano-bio Interfacementioning

confidence: 99%

Nano-bio interfaces probed by advanced optical spectroscopy: From model system studies to optical biosensors

Zhang

Han

et al. 2013

Chin. Sci. Bull.

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Research in biology and medicine is a rapidly expanding field incorporating some of the most fundamental questions concerning structure, function, and purpose. The forefront of new research demands access to advanced techniques and instrumentation capable of probing these unanswered questions. Over the past several decades, nano-scale materials and devices ranging from quasione dimensional quantum dots to two dimensional graphene sheets have been engineered and have found applications in nano-bio imaging and spectroscopy. In this review, the incorporation of nanomaterials into three influential spectroscopic and microscopic techniques including fluorescence microscopy, surface plasmon resonance, and sum frequency generation will be introduced. Fluorescence imaging has visualized nanomaterials as compliments or replacements to comparable organic fluorphores, act as a quencher for FRET-based sensing, and serve as a nanoscaffold for molecular beacons. Their versatility in coating materials makes nanomaterials an excellent targeting molecule for any cellular macromolecule or structure. In addition to the targeting capabilities of nanomaterials in fluorescence imaging, surface plasmon resonance has incorporated nanomaterials for applications in signal enhancement, selectivity of target molecules, and the development of more refined and accurate detection. Functionalized nanoparticles enhance the capabilities of sum frequency generation vibrational spectroscopy by providing unique surface chemistry which alters target molecule interactions and orientations. In summary, the incorporation of nanomaterials has greatly enhanced the field of biology and medicine and has allowed for the continual advancement of not only research but instrument development. nano-bio interfaces, optical spectroscopy, fluoroscence, SERS, SFG Citation:Zhang X X, Han X F, Wu F G, et al. Nano-bio interfaces probed by advanced optical spectroscopy: From model system studies to optical biosensors. Chin Sci Bull, 2013, 58: 25372556, doi: 10.1007/s11434-013-5700-y Nanomaterials, which size ranges (1-100 nm) coincide with fundamentally important length scales in physics, are considered to be promising building blocks for future electrical, optical and optoelectronic applications [1][2][3][4][5][6][7][8]. For example, in metals, the mean free path of an electron at room temperature is ~10-100 nm [9]; the Bohr radius of photo-excited electron-hole pairs in semiconductors is ~1-10 nm [10]; and the 1-100 nm dimension is the range over which molecules assemble into nucleic acids and proteins [11]. Nanostructures on this size scale provide a unique technology to determine many critical structure/function relationships of biological molecules at the cellular level without introducing substantial interference. Advances in nanotechnology have developed at several stages: materials, devices, and systems. A decade ago, extensive research has focused on the development of various methods to precisely control the synthesis of nanomaterials. Therefore, many differ...

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“…26,27 There are also recent reports of linking wet-chemically synthesized shape-controlled colloidal nanoparticles to (surface-modified) quartz prisms ( Figure 2d) and using total internal reflection geometry to yield higher signal. 28,29 The latter represents a promising route of applying VSFG to technical materials.…”

Section: Catalytically Active Surfacesmentioning

confidence: 99%

Sum Frequency Laser Spectroscopy during Chemical Reactions on Surfaces

Rupprechter¹

2007

MRS Bull.

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The surface specificity of vibrational sum frequency generation (VSFG) spectroscopy allows one to characterize adsorbed and reacting molecules on catalyst surfaces while the catalyst functions at high pressure and high temperature. VSFG spectroscopy can be carried out in different modes, including scanning, broadband, time-resolved, and polarization-dependent, and has been applied to various active surfaces. Single-crystal and nanoparticle model catalysts have mostly been used, which are typically prepared under ultrahigh vacuum, but applications to powder materials have been reported recently. In this article, the fundamentals and technical aspects of VSFG are summarized, and its benefits are illustrated by case studies of elementary processes of heterogeneous catalysis.involved electrons, atoms, ions, etc.) or, if compatible, are then dominated by the gas-phase contribution, which obscures the surface species information.For many years, VSFG remained one of the very few techniques that allowed for in situ (or operando) 13,14 studies of welldefined surfaces. Recent advances in the high-pressure (HP) variants of, for instance, polarization-modulation infrared reflection absorption spectroscopy (PM-IRAS), x-ray photoelectron spectroscopy (HP-XPS), scanning tunneling microscopy (HP-STM), or transmission electron microscopy (HP-TEM) have filled the surface scientist's toolbox for now. For a description of these methods, we refer to the works cited in References 11 and 15, and we focus on VSFG below. In this article, we restrict ourselves to well-defined surfaces such as single crystals and evaporated metal oxide systems and exclude conventional high-surface-area catalysts. The high surface area of the active component in technical catalysts facilitates in situ vibrational studies, for example, by infrared or Raman spectroscopy. 16 Vibrational Sum Frequency Generation Spectroscopy: PrinciplesVSFG makes use of the second-order nonlinear optical process of sum frequency generation, that is, two light waves at different frequencies interact in a medium characterized by a nonlinear susceptibility tensor χ (2) and generate a wave at the sum of their frequencies. 1 Because this nonlinear process typically produces only a small signal, high incident light intensities (i.e., pulsed lasers) are required. To acquire an SFG vibrational spectrum of adsorbed/reacting molecules on a metal catalyst, two short (e.g., picosecond) laser pulses are spatially and temporally overlapped on the sample (Figure 1a). One input beam is in the visible range at fixed frequency (ω vis ), and the second is tunable in the mid-IR region (ω IR ) to probe the vibrational modes of the surface species. In a simplified picture, when the IR beam is tuned through a vibrational resonance of the adsorbate, it induces a vibrational transition from the ground state to an excited state, and simultaneously, the visible beam induces a transition to a higher-energy virtual state through an anti-Stokes Raman process (see transition from higher to lower vibrational ...

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Sum Frequency Generation Studies of Surfaces of High-Surface-Area Powdered Materials

Cited by 44 publications

References 17 publications

Sum Frequency Generation Vibrational Spectroscopy of Pyridine Hydrogenation on Platinum Nanoparticles

Sum Frequency Generation Vibrational Spectroscopy of Pyridine Hydrogenation on Platinum Nanoparticles

Nano-bio interfaces probed by advanced optical spectroscopy: From model system studies to optical biosensors

Sum Frequency Laser Spectroscopy during Chemical Reactions on Surfaces

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