Molecular Bonding and Interactions at Aqueous Surfaces as Probed by Vibrational Sum Frequency Spectroscopy

Richmond, Geraldine L.

doi:10.1021/cr0006876

Cited by 1,060 publications

(1,498 citation statements)

References 191 publications

(579 reference statements)

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“…It is thereby free, and protrudes out of the water phase, confirming earlier predictions from computations. 11 Roughly the same picture of the existence of the free OH bonds at the interface has since been consistently observed in SFG experiments by Richmond, 5 Eisenthal, 12 Allen, 13 and Gan et al, 14 and also in computer simulations. 3,[15][16][17][18][19] The structure of water at the hydrophobic organic/water interfaces was shown to be similar to that at the air/water interface.…”

Section: Introductionsupporting

confidence: 58%

Microscopic structure and dynamics of air/water interface by computer simulations—comparison with sum-frequency generation experiments

Wang

Hodas

Jung

et al. 2011

Phys. Chem. Chem. Phys.

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The air/water interface was simulated and the mode amplitudes and their ratios of the effective nonlinear sum-frequency generation (SFG) susceptibilities (A eff 's) were calculated for the ssp, ppp, and sps polarization combinations and compared with experiments. By designating ''surface-sensitive'' free OH bonds on the water surface, many aspects of the SFG measurements were calculated and compared with those inferred from experiment. We calculate an average tilt angle close to the SFG observed value of 35, an average surface density of free OH bonds close to the experimental value of about 2.8 Â 10 18 m À2 , computed ratios of A eff 's that are very similar to those from the SFG experiment, and their absolute values that are in reasonable agreement with experiment. A one-parameter model was used to calculate these properties. The method utilizes results available from independent IR and Raman experiments to obtain some of the needed quantities, rather than calculating them ab initio. The present results provide microscopic information on water structure useful to applications such as in our recent theory of on-water heterogeneous catalysis.

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Section: Introductionsupporting

confidence: 58%

Microscopic structure and dynamics of air/water interface by computer simulations—comparison with sum-frequency generation experiments

Wang

Hodas

Jung

et al. 2011

Phys. Chem. Chem. Phys.

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“…The square root of the SFG intensity at 2878 cm -1 is used since it is proportional to the population of the target species (i.e., DPPC in domain (ii)) based on the theory of SFG. [42][43][44][45][46][47] It is interesting to note that the SFG profile fits well with the fraction domain (ii), i.e., ii. Both measurements of the AFM and SFG exhibit a maximum around 41°C, indicating that the two independent observations well correlate with each other.…”

Section: Comparison Between Sfg and Afm Observations During The Phasementioning

confidence: 92%

Phase transition behaviors of the supported DPPC bilayer investigated by sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM)

Tong

Peng

et al. 2016

Phys. Chem. Chem. Phys.

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The phase transition behaviors of a supported bilayer of dipalmitoylphosphatidylcholine (DPPC) have been systematically evaluated by in situ sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM). By using an asymmetric bilayer composed of per-deuterated and per-protonated monolayers, i.e., DPPC-d75/ DPPC and symmetric bilayer of DPPC/DPPC, we were able to probe the molecular structural changes during the phase transition process of the lipid bilayer by SFG spectroscopy. It was found that the DPPC bilayer is sequentially melted from the top (adjacent to the solution) to bottom leaflet (adjacent to the substrate) over a wide temperature range. The conformational ordering of the supported bilayer does not decrease (even slightly increases) during the phase transition process. The conformational defects in the bilayer can be removed after the complete melting process. The phase transition enthalpy for the bottom leaflet was found to be approximately three times greater than that for the top leaflet, indicating a strong interaction of the lipids with the substrate. The present SFG and AFM observations revealed similar temperature dependent profiles. Based on these results, the temperature-induced structural changes in the supported lipid bilayer during its phase transition process are discussed in a comparison with previous studies.

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“…[31][32][33][34] VSFG spectroscopy is a second-order nonlinear spectroscopic technique that, under the electric dipole approximation, occurs only in the region of the material in which the inversion symmetry is broken, specifically at the interface. The vibrational signatures of an adsorbate in the mid-IR region are sensitive to the local environment, so VSFG spectroscopy can be used in unraveling the adsorbate-adsorbate and adsorbate-substrate interactions.…”

Section: Introductionmentioning

confidence: 99%

Vibrational Sum-Frequency Spectroscopic Investigation of the Structure and Azimuthal Anisotropy of Propynyl-Terminated Si(111) Surfaces

et al. 2017

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Vibrational sum-frequency generation (VSFG) spectroscopy was used to investigate the orientation and azimuthal anisotropy of the C-H stretching modes for propynyl-terminated Si(111) surfaces, Si-C≡C-CH 3 . VSFG spectra revealed symmetric and asymmetric C-H stretching modes in addition to a Fermi resonance mode resulting from the interaction of the asymmetric C-H bending overtone with the symmetric C-H stretching vibration. The polarization dependence of the C-H stretching modes was consistent with the propynyl groups oriented such that the Si-C≡C bond is normal to the Si(111) surface. The azimuthal angle dependence of the resonant C-H stretching amplitude revealed no rotational anisotropy for the symmetric C-H stretching mode and a 3-fold rotational anisotropy for the asymmetric C-H stretching mode in registry with the 3-fold symmetric Si(111) substrate. The results are consistent with expectation that the C-H stretching modes of a -CH 3 group are decoupled from the Si substrate due to a -C≡C-spacer. In contrast, the methyl-terminated Si(111) surface, Si-CH 3 , was previously reported to have pronounced vibronic coupling of the methyl stretch modes to the electronic bath of bulk Si. Vacuum-annealing of propynyl-terminated Si(111) resulted in increased 3-fold azimuthal anisotropy for the symmetric stretch, suggesting that removal of

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Molecular Bonding and Interactions at Aqueous Surfaces as Probed by Vibrational Sum Frequency Spectroscopy

Cited by 1,060 publications

References 191 publications

Microscopic structure and dynamics of air/water interface by computer simulations—comparison with sum-frequency generation experiments

Microscopic structure and dynamics of air/water interface by computer simulations—comparison with sum-frequency generation experiments

Phase transition behaviors of the supported DPPC bilayer investigated by sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM)

Vibrational Sum-Frequency Spectroscopic Investigation of the Structure and Azimuthal Anisotropy of Propynyl-Terminated Si(111) Surfaces

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