Surface second-harmonic generation at air/solvent and solvent/solvent interfaces

Luca, Alfio A. Tamburello; Hébert, Philippe; Brevet, P. F.; Girault, Hubert H.

doi:10.1039/ft9959101763

Cited by 48 publications

(40 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Finally, an explanation is warranted as to why there is a drop, rather than an increase, in the signal upon adsorption of water (or ice) on the surface (of either mica or sapphire). The SHG response reflects the overall arrangements of the polar entities at the interface between two isotropic media (Fordyce et al, 2001;Goh et al, 1988;Luca et al, 1995). This signal intensity is expected to increase when a single (or a few non-centrosymmetric) layer(s) of water or ice is (are) formed at (or added to) the surface, while SHG intensity decreases upon deposition freezing, condensation, and the growth of liquid layers by diffusion as can be seen in Figs.…”

Section: Resultsmentioning

confidence: 93%

“…In the system described here, the SHG signal originates in the nonresonant electric dipolar contribution of the interfacial molecules. The signal response relates to the overall arrangements of the interfacial entities (Fordyce et al, 2001;Goh et al, 1988;Luca et al, 1995) and is proportional to the incident field and the second-order nonlinear susceptibility χ (2) of the interface. When the interface is charged, due to this charge, the static electric field can induce a third-order nonlinear polarization due to the contribution of the thirdorder nonlinear susceptibility χ (3) of the solution (Ong et al, 1992;Zhao et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Direct molecular-level characterization of different heterogeneous freezing modes on mica – Part 1

Abdelmonem

2017

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. The mechanisms behind heterogeneous ice nucleation are of fundamental importance to the prediction of the occurrence and properties of many cloud types, which influence climate and precipitation. Aerosol particles act as cloud condensation and freezing nuclei. The surface-water interaction of an ice nucleation particle plays a major, not well explored, role in its ice nucleation ability. This paper presents a real-time molecular-level comparison of different freezing modes on the surface of an atmospherically relevant mineral surface (mica) under varying supersaturation conditions using second-harmonic generation spectroscopy. Two sub-deposition nucleation modes were identified (one-and two-stage freezing). The nonlinear signal at the water-mica interface was found to drop following the formation of a thin film on the surface regardless of (1) the formed phase (liquid or ice) and (2) the freezing path (one or two step), indicating similar molecular structuring. The results also revealed a transient phase of ice at water-mica interfaces during freezing, which has a lifetime of around 1 min. Such information will have a significant impact on climate change, weather modification, and the tracing of water in hydrosphere studies.

show abstract

Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Direct molecular-level characterization of different heterogeneous freezing modes on mica – Part 1

Abdelmonem

2017

Atmos. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…1,2, 3,4,5,6,7,8,9,10,11,12 In the early days of the development of SHG for interface studies, it has been fully realized that, in applying SHG to real problems, it is important to know how to assess the relative magnitudes of the interface (local) contribution and the still possibly significant bulk electric-quadrupole and magnetic-dipole (nonlocal) contributions to the SHG signal. 5,13,14,15 Even though there were exchanges of debates on whether SHG can be an effective probe for isotropic liquid interfaces, i.e.…”

Section: Introductionmentioning

confidence: 99%

Reconsideration of second-harmonic generation from isotropic liquid interface: Broken Kleinman symmetry of neat air/water interface from dipolar contribution

Zhang

Dong

et al. 2005

The Journal of Chemical Physics

View full text Add to dashboard Cite

It has been generally accepted that there are significant quadrupolar and bulk contributions to the second harmonic generation (SHG) reflected from the neat air/water interface, as well as common liquid interfaces. Because there has been no general methodology to determine the quadrupolar and bulk contributions to the SHG signal from a liquid interface, this conclusion was reached based on the following two experimental phenomena. Namely, the broken of the macroscopic Kleinman symmetry, and the significant temperature dependence of the SHG signal from the neat air/water interface. However, because sum frequency generation vibrational spectroscopy (SFG-VS) measurement of the neat air/water interface observed no apparent temperature dependence, the temperature dependence in the SHG measurement has been reexamined and proven to be an experimental artifact. Here we present a complete microscopic analysis of the susceptibility tensors of the air/water interface, and show that dipolar contribution alone can be used to address the issue of broken of the macroscopic Kleinman symmetry at the neat air/water interface. Using this analysis, the orientation of the water molecules at the interface can be obtained, and it is consistent with the measurement from SFG-VS. Therefore, the key rationales to conclude significantly quadrupolar and bulk contributions to the SHG signal of the neat air/water interface can no longer be considered as valid as before. This new understanding of the air/water interface can shed light on our understanding of the nonlinear optical responses from other molecular interfaces as well.

show abstract

“…For the study of surface phenomena at various interfaces, the total internal reflection (TIR) condition has been used in a number of spectroscopic measurements, 1 such as fluorometry, [2][3][4][5][6][7][8][9] surface enhanced infrared spectroscopy (SEIRA), [10][11][12] second harmonic generation, [13][14][15][16][17][18][19][20][21] and sum frequency generation (SFG). [22][23][24][25] There are two advantages when one uses the TIR condition.…”

Section: Introductionmentioning

confidence: 99%

Total-internal-reflection Broad-bandwidth Sum Frequency Generation Spectroscopy of Hexadecanethiol Adsorbed on Thin Gold Film Deposited on CaF, 2

et al. 2003

View full text Add to dashboard Cite

IntroductionFor the study of surface phenomena at various interfaces, the total internal reflection (TIR) condition has been used in a number of spectroscopic measurements, 1 such as fluorometry, 2-9 surface enhanced infrared spectroscopy (SEIRA), [10][11][12] second harmonic generation, [13][14][15][16][17][18][19][20][21] and sum frequency generation (SFG). [22][23][24][25] There are two advantages when one uses the TIR condition. First, both incident light to the interface and reflected light or generated light from the interface travel in only one of the two phases adjacent to the interface, which circumvents bulk absorption by the other phase. One corollary is the freedom of changing the composition of the adjacent phase that has a lower refractive index. Second, high sensitivity to the interfaces can be achieved owing to the enhancement of the electric field at the interfaces. 1 The TIR arrangement can be employed at metal interfaces if a very thin metal film is used to avoid the absorption of light. It has been successfully employed to detect adsorbed species on metal in the SEIRA, where the thickness of the metal film is about 10 nm on a transparent substrate. [10][11][12] Recently, Williams et al. showed that the TIR arrangement can also be employed to detect SFG signals from alkanethiols adsorbed on a thin gold film. 24 However, detailed analysis of the sum frequency vibrational spectra has not been reported. SFG in the TIR arrangement has some potential as a powerful tool to study molecular orientations at metal/liquid interfaces, such as electrochemical interfaces, because it is free from bulk absorption and has interfacial sensitivity in the order of nanometers. Unlike surface plasmon resonance and capacitance measurements that have been used as sensitive means of detecting adsorption and molecular interaction at the interfaces, TIR-SFG will enable us to obtain molecular information on the solution side of the interfaces. One drawback of the TIR arrangement is the roughness of the metal surfaces. The roughness is prerequisite for high sensitivity and can complicate the interpretation of the experimental data because of the orientational distribution of molecules in comparison with those adsorbed on a single crystal surface. It is therefore of crucial importance to assess the degree of the variation in orientation of molecules.By using broad-bandwidth sum frequency generation (BBSFG) [26][27][28] we recently analyzed the orientation of alkanethiols adsorbed on Au(111). 29It is worthwhile to examine the applicability of BBSFG in the TIR condition at metal interfaces to obtain SFG spectra with higher resolution. In the present paper, we report the results of TIR-BBSFG measurements for hexadecanethiol (HDT) adsorbed on a thin gold film on CaF2. We will show that BBSFG can be successfully employed in the orientation analysis of the HDT molecules and that the methyl groups of HDT are much more randomly orientated than those on Au(111) on mica. Experimental SubstrateA hemicylindrical CaF2 prism (Pier Optic...

show abstract

Surface second-harmonic generation at air/solvent and solvent/solvent interfaces

Cited by 48 publications

References 20 publications

Direct molecular-level characterization of different heterogeneous freezing modes on mica – Part 1

Direct molecular-level characterization of different heterogeneous freezing modes on mica – Part 1

Reconsideration of second-harmonic generation from isotropic liquid interface: Broken Kleinman symmetry of neat air/water interface from dipolar contribution

Total-internal-reflection Broad-bandwidth Sum Frequency Generation Spectroscopy of Hexadecanethiol Adsorbed on Thin Gold Film Deposited on CaF, 2

Contact Info

Product

Resources

About