Analyzing the stability of second harmonic intensity provides a sensitive probe of the aggregating of conjugated molecules at the interface

Niu, Yaran; Tian, Ke; Gan, Wei; Ye, Shuji

doi:10.1016/j.molliq.2016.03.025

Cited by 10 publications

(4 citation statements)

References 40 publications

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“…The setup for SHG measurements has been described elsewhere [14,21,45]. A broadband Ti:sapphire oscillator laser (Coherent, Mira-900f) with a pulse width of approximately 130 fs and a repetition rate of 76 MHz was used.…”

Section: B Shg Setupmentioning

confidence: 99%

Orientation Angle of Molecules at Hexadecane-Water Interface Studied with Total Internal Reflection Second Harmonic Generation

Zhang

Fang

Chen

et al. 2016

Chinese Journal of Chemical Physics

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The orientation angle is an important parameter that reflects the structure of molecules at interfaces. In order to obtain this parameter, second order nonlinear spectroscopic techniques including second harmonic generation (SHG) and sum frequency generation-vibrational spectroscopy (SFG-VS) have been successfully applied through analysis of the nonlinear signal from various polarizations. In some SHG and SFG-VS experiments, total internal reflection (TIR) configuration has been adopted to get enhanced signals. However, the reports on the detailed procedure of the polarization analysis and the calculation of the orientation angle of interfacial molecules under TIR configuration are still very few. In this paper, we measured the orientation angles of two molecules at the hexadecane-water interface under TIR and Non-TIR experimental configurations. The results measured from polarization analysis in TIR configuration consist with those obtained from Non-TIR configuration. This work demonstrates the feasibility and accuracy of polarization analysis in the determination of the orientation angle of molecules at the interfaces under TIR-SHG configuration.

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Section: B Shg Setupmentioning

confidence: 99%

Orientation Angle of Molecules at Hexadecane-Water Interface Studied with Total Internal Reflection Second Harmonic Generation

Zhang

Fang

Chen

et al. 2016

Chinese Journal of Chemical Physics

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“…SHG signals may be enhanced by the resonant enhancement effect when dye molecules with noncentrosymmetric structures and high hyperpolarizability (β) are excited by lasers at proper wavelengths. , For many dyes, TPF signals are also produced upon excitation by a laser with high peak power, which may influence the accuracy for determining the SHG signal and for multimodal imaging . In previous studies, MG (malachite green) and D289 (( E )-4-(4-(diethylamino)styryl)-1-methylpyridin-1-ium) were commonly used as SHG-active molecules. − MG has a relatively high SHG efficiency and low TPF emission, so it has been used in studying energetics during its adsorption and interactions with interfaces, including gas–solid, gas–liquid, solid–liquid, and water lipid interfaces. , It is also known that MG has a higher SHG efficiency in acidic bulk solutions (pH = 4); D289 is suitable for use in neutral environments, which better resembles the biological environment. ,,, It was observed that D289 emitted a strong TPF signal, especially when it was dispersed in lipid membranes, , although this TPF differs in wavelength from the SHG emission and can be separated in spectral measurements. It is known that dyes emitting strong fluorescence may generate unwanted fluorescence backgrounds and cross-modal interference when used in multiple imaging systems, ,, which could decrease the resolution of images in a large scale.…”

Section: Introductionmentioning

confidence: 99%

“…32,35 It is also known that MG has a higher SHG efficiency in acidic bulk solutions (pH = 4); D289 is suitable for use in neutral environments, which better resembles the biological environment. 30,31,36,37 It was observed that D289 emitted a strong TPF signal, especially when it was dispersed in lipid membranes, 38,39 although this TPF differs in wavelength from the SHG emission and can be separated in spectral measurements. It is known that dyes emitting strong fluorescence may generate unwanted fluorescence backgrounds and cross-modal interference when used in multiple imaging systems, 11,18,24 nonlinear efficiency and suppressed TPF emission is highly desired.…”

Section: ■ Introductionmentioning

confidence: 99%

Modification of the Second Harmonic Generation and Fluorescence Efficiency of D289 Dye Based on a Donor–Acceptor Structure

Peng

Hou

et al. 2022

J. Phys. Chem. C

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Second harmonic generation (SHG) spectroscopy and microscopy have been widely applied in studying the interfacial processes that occur in chemical, physical, and biological systems. Efficient SHG probes are crucial for these investigations. Herein, we designed two water-soluble dyes with conjugated donor–acceptor structures (TPAP and TPAPM) and studied their second-order nonlinear optical (NLO) properties and fluorescence efficiencies. The modified molecules emitted much less two-photon fluorescence than dye D289 due to nonradiative transitions caused by molecular motions in solution. TPAPM exhibited higher NLO performance than D289 and TPAP because of the strong electron pull–push effect operating along the D−π–A backbone, and it is a promising SHG probe molecule for multimodal imaging in biological applications.

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“…1,2 Electric interactions are recognized as molecule-molecule interactions or the interaction between molecules and a static electric field, which can be induced by external sources or uneven distribution of interfacial ionic species, for example, the electric double layers at interfaces. 3 In order to understand the behavior of ions at interfaces, experimental techniques such as chemical titration, 4,5 surface tension, 6,7 surface/interface potential, [8][9][10] Brewster angle microscopy, 8,11,12 electron paramagnetic resonance spectroscopy, 13 neutron reflection 14 and second order nonlinear spectroscopic methods 4,7,[15][16][17][18][19][20][21] have been applied.…”

Section: Introductionmentioning

confidence: 99%

The ionic strength dependent zeta potential at the surface of hexadecane droplets in water and the corresponding interfacial adsorption of surfactants

Yang

Chen

et al. 2017

Soft Matter

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An anomalous maximum in the ionic strength dependent electrophoretic mobility curves has been observed in previous reports from particles dispersed in colloids. This maximum has been considered anomalous because it is contradictory with the Gouy-Chapman model. The existence of such a maximum has been attributed to specific ionic adsorption, a hairy layer at the surface, or the effect of the anomalous change of surface conductivity in different studies. It was also pointed out that the O'Brien-White approach based on the Gouy-Chapman model could be used to understand this maximum in electrophoretic mobility curves and lead to understandable zeta potential curves. This implied that the observed maximum was actually not "anomalous". In this work we report our simulation of ionic strength dependent zeta potential curves based on the O'Brien-White approach and experimental studies of the ionic strength dependent electrophoretic mobility of the hexadecane droplets in the hexadecane-water emulsions at different pH or in the presence of sodium dodecyl sulphate at varied concentrations. In some cases, the simulation shows that the calculation with the O'Brien-White approach does change the trend in the concerned ionic strength dependent curves. However, the simulation in some other cases also leads to similar trends in the ionic strength dependent electrophoretic mobility curves and zeta potential curves. In the experiments, both the existence and non-existence of such a maximum were observed and demonstrated to be system dependent. The corresponding molecular structure of the oil-water interface was then discussed with the analyses of the zeta potential curves and second harmonic generation signals recorded at the hexadecane-water interface.

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Analyzing the stability of second harmonic intensity provides a sensitive probe of the aggregating of conjugated molecules at the interface

Cited by 10 publications

References 40 publications

Orientation Angle of Molecules at Hexadecane-Water Interface Studied with Total Internal Reflection Second Harmonic Generation

Orientation Angle of Molecules at Hexadecane-Water Interface Studied with Total Internal Reflection Second Harmonic Generation

Modification of the Second Harmonic Generation and Fluorescence Efficiency of D289 Dye Based on a Donor–Acceptor Structure

The ionic strength dependent zeta potential at the surface of hexadecane droplets in water and the corresponding interfacial adsorption of surfactants

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