The temperature dependence of surface second-harmonic generation from the air-water interface

Fordyce, A. J.; Bullock, W. J.; Timson, Andrew J; Haslam, S.; Spencer‐Smith, R. D.; Alexander, Ashish; Frey, Jeremy G.

doi:10.1080/00268970010030022

Cited by 38 publications

(48 citation statements)

References 24 publications

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“…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: 92%

“…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%

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

Abdelmonem

2017

Atmos. Chem. Phys.

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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.

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Section: Resultsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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

Abdelmonem

2017

Atmos. Chem. Phys.

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“…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

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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.

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“…1,2,3,4 Among them, air/water interface has been intensively investigated theoretically or experimentally over the last decades. Spectroscopy, molecular structure and dynamics at air/water interface is studied with theoretical analysis such as ab initio calculation or molecular dynamics simulation, 5,6,7,8,9,10,11,12,13 or experimental techniques such as X-ray reflection, 14,15 Stimulated Raman Scattering (SRS), 16 Near-edge X-Ray Adsorption Fine Structure (NEXAFS), 17 Second Harmonic Generation (SHG), 18,19 as well as Sum Frequency Generation, etc. 20,21,22,23,24,25,26,27,28 Among these experimental techniques, Second Harmonic Generation and Sum Frequency Generation are the most important methods for molecular interface studies because of their surface sensitivity and specificity.…”

Section: Introductionmentioning

confidence: 99%

Polarization and experimental configuration analyses of sum frequency generation vibrational spectra, structure, and orientational motion of the air/water interface

Gan¹,

Wu²,

Zhang³

et al. 2006

The Journal of Chemical Physics

250

332

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Here we report a detailed study on spectroscopy, structure and dynamics of water molecules at air/water interface, investigated with Sum Frequency Generation Vibrational Spectroscopy (SFG-VS). Quantitative polarization and experimental configuration analysis of the SFG data in different polarizations with four sets of experimental configurations can shed new lights on our present understanding of the air/water interface. Firstly, we concluded that the motion of the interfacial water molecules can only be in a limited angular range, instead rapidly varying over a broad angular range in the vibrational relaxation time suggested previously. Secondly, because different vibrational modes of different molecular species at the interface has different symmetry properties, polarization and symmetry analysis of the SFG-VS spectral features can help assignment of the SFG-VS spectra peaks to different interfacial species. These analysis concluded that the narrow 3693cm −1 and broad 3550cm −1 peaks belong to C∞v symmetry, while the broad 3250cm −1 and 3450cm −1 peaks belong to the symmetric stretching modes with C2v symmetry. Thus, the 3693cm −1 peak is assigned to the free OH, the 3550cm −1 peak is assigned to the single hydrogen bonded OH stretching mode, and the 3250cm −1 and 3450cm −1 peaks are assigned to interfacial water molecules as two hydrogen donors for hydrogen bonding (with C2v symmetry), respectively. Thirdly, analysis of the SFG-VS spectra concluded that the singly hydrogen bonded water molecules at the air/water interface have their dipole vector direct almost parallel to the interface, and is with a very narrow orientational distribution. The doubly hydrogen bond donor water molecules have their dipole vector point away from the liquid phase.

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The temperature dependence of surface second-harmonic generation from the air-water interface

Cited by 38 publications

References 24 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

Polarization and experimental configuration analyses of sum frequency generation vibrational spectra, structure, and orientational motion of the air/water interface

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