Sum-frequency spectroscopy in total internal reflection geometry: signal enhancement and access to molecular properties

Löbau, J.; Wolfrum, K.

doi:10.1364/josab.14.002505

Cited by 94 publications

(117 citation statements)

References 33 publications

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“…Assuming local C 3v symmetry for the methyl group and averaging over methyl internal rotations, the r -intensity will vanish for a methyl tilt angle of zero with respect to the surface normal. 52,53 As the tilt angle increases, the r -/r + ratio will increase. At a 90°tilt, the intensity of both modes will vanish, but the limiting r -/r + ratio will be a maximum.…”

Section: Discussionmentioning

confidence: 99%

In Situ, Vibrationally Resonant Sum Frequency Spectroscopy Study of the Self-Assembly of Dioctadecyl Disulfide on Gold

et al. 2002

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We report the results of an in situ, vibrationally resonant sum frequency generation (SFG) spectroscopy study of the assembly of perdeuterated dioctadecyl disulfide on gold substrates from ethanol solutions under laminar flow conditions. The coverage evolution of the SFG spectra can be well described by the coexistence of two distinct phases: a low-coverage, disordered phase and the full-coverage crystalline phase. The structure of the adsorbed thiolate fragments in the low-coverage phase is disordered but upright (as opposed to lying completely in the surface plane), characterized by significant gauche defects in the backbone but a near-normal orientation for the terminal methyl group. The crystalline phase is marked by an erect all-trans configuration of the alkane chain. The kinetics of the evolution of these two phases can be quantitatively described by a simple model, consistent with phase coexistence above a critical density of the disordered phase.

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Section: Discussionmentioning

confidence: 99%

In Situ, Vibrationally Resonant Sum Frequency Spectroscopy Study of the Self-Assembly of Dioctadecyl Disulfide on Gold

et al. 2002

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“…(2) ) µ yyz:aab ‚ aab,V + µ yyz:bbb ‚ bbb,V + µ yyz:ccb ‚ ccb,V (7) SSP,as (2) ) yyz,as (2) ) µ yyz:aba ‚ aba,as + µ yyz:baa ‚ baa,as (8) Lorentzian distributions generated too much intensity in the 3600 cm -1 region of the spectrum, preventing a good fit to the data. A significantly better fit was obtained by considering each transition using the lineshape profile described earlier.…”

Section: Ijkvmentioning

confidence: 99%

The Analysis of Interference Effects in the Sum Frequency Spectra of Water Interfaces

et al. 2000

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Vibrational sum frequency (VSF) spectroscopy has been increasingly used in recent years to measure the vibrational spectroscopy of molecules at surfaces. Some of the more important systems examined in such studies involve the surface of liquid water. Unfortunately, obtaining spectral fits to vibrational spectra acquired in these studies can be challenging. The difficulty arises from the wide range of contributing vibrational modes, the breadth of the spectral peaks for hydrogen-bonded water molecules, and the complex interference effects that can arise between adjacent vibrational modes because of the coherent nature of the sum frequency process. In this paper, we describe a detailed method for obtaining spectral fits to such VSF data that takes into account a range of water species present at a water surface and the possible interference between these contributing modes. The relationship between the spectral information derived and the molecular orientation is also given. This analysis is applied to two cases, VSF spectra of water measured at the CCl 4 /H 2 O interface and at the air/H 2 O interface.

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“…Vibrational sum frequency generation spectroscopy experiments have mainly been performed using scanning SFG instruments with pulse-widths in the ps (picosecond) [15][16][17][18][19] or ns (nanosecond) [20][21][22][23] time regime that produce relatively narrow spectral bandwidths. In a scanning SFG system the nonlinear crystals used to convert a portion of the visible wavelength beam to an infrared beam are angle tuned.…”

Section: Introductionmentioning

confidence: 99%

Broadband Vibrational Sum Frequency Generation Spectroscopy of a Liquid Surface

Hommel

Allen

2001

ANAL. SCI.

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Atmospheric aerosol surface chemistry, polar stratospheric cloud surface chemistry, and soil-water interfacial chemistry are examples of environmentally relevant interfaces that are not well understood at the molecular level. In light of the need to understand the molecular-level details of one of these interfacial systems, we demonstrate here advances in the field of surface spectroscopy, in particular, broad-bandwidth sum frequency generation (BBSFG) spectroscopy.Broad-bandwidth sum frequency generation technology is gaining recognition for studying solid-surface structure and chemistry. 6-13 However, acquiring BBSFG spectra from liquid surfaces has been more elusive due to the inherently small nonlinear response from many liquid surfaces. Nevertheless, we show here, for the first time, BBSFG spectra obtained from a liquid surface.There have been a significant number of surface spectra published using scanning SFG instruments from liquid surfaces; however, until now a BBSFG spectrum from a liquid surface had not been obtained. A new double-amplifier design, which is explained in a previously published paper 14 was used for the acquisition of these BBSFG spectra. The data presented in this paper show that BBSFG can now be successfully utilized to probe the vibrational modes of molecules at liquid surfaces. We also demonstrate the time-resolved capability of this BBSFG system to acquire data in as few as 500 ms.Visible-infrared BBSFG spectroscopy provides molecularlevel information about molecular species at an interface in the form of polarization-dependent vibrational data from the surface molecules. The strength of BBSFG spectroscopy lies in its inherent ability to attain a full surface spectrum within one pulse of the laser system, thus potentially allowing temporally resolved spectroscopic data from reactions occurring at an interface.Vibrational sum frequency generation spectroscopy experiments have mainly been performed using scanning SFG instruments with pulse-widths in the ps (picosecond) [15][16][17][18][19] or ns (nanosecond) 20-23 time regime that produce relatively narrow spectral bandwidths. In a scanning SFG system the nonlinear crystals used to convert a portion of the visible wavelength beam to an infrared beam are angle tuned. The angle tuning causes small directional changes in the beam path, which can affect the spatial overlap of the two incident beams at the sample surface. This can compromise the spectral reproducibility and the shape of the scanning SFG spectrum. Scanning SFG systems, by the nature of the system, are primarily used on equilibrium or static interfaces. Although scanning sum frequency instruments are still considered stateof-the-art for surface spectroscopic technology, a new generation of broad-bandwidth (non-scanning) SFG instruments have taken center-stage because of their ability to capture a full spectrum within one pulse of the laser, thereby providing timeresolved surface data in addition to static or equilibrium surface data.Although sum frequency generation has b...

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Sum-frequency spectroscopy in total internal reflection geometry: signal enhancement and access to molecular properties

Cited by 94 publications

References 33 publications

In Situ, Vibrationally Resonant Sum Frequency Spectroscopy Study of the Self-Assembly of Dioctadecyl Disulfide on Gold

In Situ, Vibrationally Resonant Sum Frequency Spectroscopy Study of the Self-Assembly of Dioctadecyl Disulfide on Gold

The Analysis of Interference Effects in the Sum Frequency Spectra of Water Interfaces

Broadband Vibrational Sum Frequency Generation Spectroscopy of a Liquid Surface

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