Journal of Physical Chemistry C
·
2022
·
IF 4.177
Yongming Hong,Jiali He,Cuiyun Zhang,Xinping Wang
The structure of water at the graphene oxide (GO)/water interface has received considerable attention due to the high performance of GO in a wide number of applications. In this work, a face-up geometry of sum frequency generation (SFG) vibrational spectroscopy was employed to deduce the structure of water at the GO/water interface in which GO nanosheets were covered onto the water surface via Langmuir compression. The SFG results showed that the intense OH stretching bands at the range of 3000–3600 cm–1 were predominant in the spectrum with high GO coverage, which is mainly due to the third-order susceptibility χ(3) response from the water orientation in the electrical double layer induced by the static electric field of the negatively charged GO surface. In addition, the second-order susceptibility χ(2) response was relatively weak, suggesting that a few water molecules formed a H-bonding network within the closest GO surface. This work is beneficial to the in-depth understanding of water in contact with GO-based materials.
研究领域:
材料科学
·
表面化学
✓ 已验证
DOI
高影响因子
FOOD CHEMISTRY
·
2020
·
IF 6.306
Fanghui Fan,Pengyu Xiang,Liqing Zhao
Lactose is a common component found in many foods and dairy products. In this study, the vibrational signatures in the crystalline structure of α -, β -, and α -lactose monohydrate were calculated based on quantum chemistry calculation (QCC), whilst the vibrational spectra in freeze-dried lactose equilibrated at various a w and pre-humidified amorphous lactose (0.33 a w ) stored from 25 to 95 °C were determined by using Raman and FT-IR spectroscopies. The vibrational signatures of crystalline lactose were affected by the presence of water according to QCC results. Water plasticization, involving water insertion, exposure of H-bonding sites, and structure disruption, was accelerated by storage temperature based on Raman and FT-IR spectra analysis. Raman spectra indicated that the crystal formation of lactose was affected by a w and storage temperature. Moreover, the spectral changes assigned in OH group provided useful information for determining the critical a w or temperature when T g -related molecular mobility occurred in lactose-containing products.
研究领域:
食品科学
·
物理化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2024
·
IF 3.7
Zhaohui Xu,Gaoming Li,Yinyu Zhang,Yeping Wu,Xiaolin Lu
Generally, for adhesive joints, the polar water molecules in humid environments can have a critical effect on the interfacial structures and structural evolution adjacent to the solid substrates. Regarding this, it is still a big challenge to detect and understand the interfacial hygrothermal aging process at the molecular level in real time and in situ. In this study, to trace the interfacial hygrothermal aging process of a classical epoxy formula containing diglycidyl ether of biphenyl A (DGEBA) and 2,2′-(ethylenedioxy) diethylamine (EDDA) with sapphire and fused silica in a typical hygrothermal environment (85 °C and 85% RH), sum frequency generation (SFG) vibrational spectroscopy was used to probe the molecular-level interfacial structural change over the time. The structural evolution dynamics at the buried epoxy/sapphire and epoxy/silica interfaces upon hygrothermal aging were revealed directly in situ. The interfacial delamination during hygrothermal aging was also elucidated from the molecular level. Upon hygrothermal aging, the interfacial CH signals, such as the ones from methyl, methylene, and phenyl groups, decreased significantly and the water OH signals increased substantially, indicating the water molecules had diffused into the interfaces and destroyed the original interactions between the epoxy formula and the substrates. Further analysis indicates that when the integrated signals in the CH range declined to their minimum and leveled off, the interfacial delamination happened. The tensile experiment proved the validity of these spectroscopic experimental results. Our study provides first-hand and molecular-level evidence on a direct correlation between the diffusion of the surrounding water molecules into the interface and the evolution/destruction of the interfacial structures during hygrothermal aging. More importantly, it is proved, SFG can be developed into a powerful tool to noninvasively reveal the local interfacial delamination in real time and in situ under extreme hygrothermal conditions, complemented by the mechanic test.
研究领域:
材料科学
·
表面化学
✓ 已验证
DOI
PubMed
高影响因子
CHINESE JOURNAL OF CHEMICAL PHYSICS
·
2012
·Vol. 25
·期 5
·526-532
·
IF 0.692
Wang Jian,Qiu Xue-jun,Wang Yan-mei,Zhang Song,Zhang Bing
Normal vibrations of ethylbenzene in the first excited state have been studied using resonant two-photon ionization spectroscopy. The band origin of ethylbenzene of S 1 ←S 0 transition appeared at 37586 cm −1 . A vibrational spectrum of 2000 cm −1 above the band origin in the first excited state has been obtained. Several chain torsions and normal vibrations are obtained in the spectrum. The energies of the first excited state are calculated by the time-dependent density function theory and configuration interaction singles (CIS) methods with various basis sets. The optimized structures and vibrational frequencies of the S 0 and S 1 states are calculated using Hartree-Fock and CIS methods with 6-311++G(2d,2p) basis set. The calculated geometric structures in the S 0 and S 1 states are gauche conformations that the symmetric plane of ethyl group is perpendicular to the ring plane. All the observed spectral bands have been successfully assigned with the help of our calculations.
研究领域:
物理化学
·
量子化学
✓ 已验证
DOI
高影响因子
POLYMER
·
2013
·
IF 3.379
Bolin Li,Jie Zhou,Xin Xu,Jincheng Yu,Wei Shao,Yong Fang,Xiaolin Lu
The surface sum frequency generation (SFG) vibrational spectroscopic spectra of PMA and PMMA films prepared from solvents with different qualities were found different. This suggests that the surface molecular structures of PMA and PMMA films were affected by the solvent quality. A simple phenomenological model was used to describe the chain conformational order at the polymer surface by correlating the SFG resonant signals of the side chromophoric groups to the introduced chain arc included angle. This model is believed to be applicable for polymers with short and rigid side chromophores active for the SFG spectroscopy.
研究领域:
材料科学
·
光谱学
✓ 已验证
产品关联
DOI
高影响因子
INORGANIC CHEMISTRY
·
2018
·
IF 4.7
Qian Peng,J. Timothy Sage,Yulong Liu,Zijian Wang,Michael Y. Hu,Jiyong Zhao,E. Ercan Alp,W. Robert Scheidt,Jianfeng Li
Compared to well studied diatomic ligands (NO, CN–, CO), the axial bonds of carbene hemes is much less known although its significance in biological chemistry. The unusually large quadrupole splitting (ΔEQ = +2.2 mm·s–1) and asymmetric parameter (η = 0.9) of the five-coordinate heme carbene [Fe(TTP)(CCl2)], which is the largest among all known low spin ferrohemes, has driven investigations by means of Mössbauer effect Nuclear Resonance Vibrational Spectroscopy (NRVS). Three distinct measurements on one single crystal (two in-plane and one out-of-plane) have demonstrated comprehensive vibrational structures including stretch (429) and bending modes (472 cm–1) of the axial Fe–CCl2, and revealed iron vibrational anisotropy in three orthogonal directions for the first time. Frontier orbital analysis especially comparisons with diatomic analogues (NO, CN–, CO) suggest that CCl2, similar to NO, has led to strong but anisotropic π bonding in a ligand-based “4C”-coordinate which induced the vibrational anisotropies and very large Mössbauer parameters. This is contrasted to CN– and CO complexes which possess a porphyrin-based “4N”-coordinate electronic and vibrational structures due to inherent on-axis linear ligation.
研究领域:
生物化学
·
配位化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2022
·
IF 4.331
Zhaohui Xu,Yinyu Zhang,Yeping Wu,Xiaolin Lu
The formation of the interfacial adhesion between an epoxy adhesive and a substrate was normally accompanied by the epoxy curing process on the substrate. Although the debate on the formation mechanism of the interfacial adhesion is still ongoing, this issue can causally be resolved by studying the interfacial structural formation between the epoxy adhesive and the substrate. Herein, to reveal the interfacial structural formation of a representative formula composed of epoxy (digylcidyl ether of biphenyl A, DGEBA) and amine hardener (2,2′-(ethylenedioxy) diethylamine, EDDA) with the steel substrate upon curing and postcuring treatments, sum-frequency generation (SFG) vibrational spectroscopy with a sandwiched transparent window/epoxy adhesive/steel setup was applied to detect and track the buried molecular-level structures at the epoxy adhesive/steel interface. An X-ray photoelectron spectroscopic (XPS) experiment was performed to probe the intentionally exposed interface to disclose the occurring interfacial chemical reaction. The reaction between the epoxy groups and the steel-surface OH groups and the molecular reconstruction of interfacial epoxy methyl groups upon curing and postcuring steps were confirmed. The latter also indirectly indicated the formation of the additional hydrogen bonding and the former bonding reaction at the interface. The above two spectroscopic experimental results matched up with the further examination of the adhesion strength. Therefore, this work elucidates the formation of the interfacial bonding between the epoxy formula and the steel substrate upon curing and postcuring treatments at the molecular level, thus providing an in-depth insight into the origin of the interfacial adhesion.
研究领域:
材料科学
·
表面化学
✓ 已验证
DOI
高影响因子
Chemical Science
·
2025
·
IF 7.4
Xiaoxuan Zheng,Junjun Tan,Quanbing Pei,Yi Luo,Shuji Ye
Elucidating the ultrafast dynamics of interfacial molecules at the single-molecule level is pivotal for advancing our understanding of fundamental chemical and biological processes. Here, for the first time, we realized detection of ultrafast vibrational dynamics by a novel technique that integrates femtosecond sum frequency generation vibrational spectroscopy (SFG-VS) with nanoparticle-on-mirror (NPoM) nanocavities (NPoM-SFG-VS). Using a symmetric stretching vibrational mode of para-nitrothiophenol (νNO2) as a probe, we have successfully identified signals from self-assembled monolayers (SAMs) comprising ∼60 molecules, demonstrating the single-molecule-level sensitivity of the NPoM-SFG-VS. The dephasing time and vibrational relaxation time of νNO2 at the single-molecule level were determined to be 0.33 ± 0.01 ps and 2.2 ± 0.2 ps, respectively. By controlling the solution concentration used to prepare SAMs (C), a correlation between peak frequency of νNO2 and C is established. It was found that single-molecule-level detection was achieved at C ≤ 10−10 M. With this protocol, microregion distribution of interfacial molecule number can be mapped using NPoM-SFG imaging. This work provides insights into the structures and vibrational dynamics of individual interfacial molecules, aiding in precise engineering of surface properties and reactivity.
研究领域:
化学
·
物理学
·
表面科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2023
·
IF 3.9
Chu Wang,Chenxi Hou,Jiayou Pu,Siyu Li,Shiao Luo,Xiaofeng Han,Xiaolin Lu
Multidrug-resistant (MDR) pathogens have been a growing threat to human health over the years. Antimicrobial peptides (AMPs) with broad-spectrum antibiotic activity, as a promising therapeutic candidate, have shown tremendous capability against MDR pathogens. To acquire novel AMPs with better efficacy, we should dig into the antimicrobial mechanism by which AMPs perform their functions. In this study, the interaction processes between three representative AMPs (maculatin 1.1-G15, cupiennin 1a, and aurein 1.2) and the model membrane dDPPG/DPPG bilayer were investigated via sum frequency generation (SFG) vibrational spectroscopy. Two interaction modes for the membrane-bound AMPs were differentiated, i.e., the loosely adsorbed one and the tightly adsorbed one. In the loosely adsorbed mode, AMPs are bound to the bilayer mainly by the electrostatic attraction between the positively charged residues of AMPs and the negatively charged head groups of the lipids. After the charged AMPs and lipids were neutralized by the counter ions, the desorption of AMPs from the membrane lipids happened, as evidenced by the disappearance of the SFG signals from membrane-bound AMPs. While in the tightly adsorbed mode, besides the charged attraction, AMPs are additionally inserted into the membrane lipids via the hydrophobic interaction. Even when the electrostatic attraction was neutralized by the counter ions, the hydrophobic interaction still led to the firm adsorption of AMPs onto the already-neutralized bilayer lipids, as evidenced by the presence of clear SFG signals from membrane-bound AMPs. We thus established a feasible protocol to expand the application of SFG, namely classifying the adsorption modes of AMPs. Such knowledge will surely promote the development and application of AMPs with high efficacy.
研究领域:
生物物理学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Science and Engineering B-Advanced Functional Solid-State Materials
·
2015
·
IF 2.169
Xinghao Lin,Yanming Zhao,Youzhong Dong,Quan Kuang,Zhiyong Liang,Danlin Yan,Xudong Liu
A metaphosphate NaFe(PO 3 ) 3 compound has been obtained by solid state method here. This title compound belongs to the orthorhombic structure with the space group of P 2 1 2 1 2 1 (No. 19) and lattice parameters of a = 14.3390(3) Å, b = 14.3374(2) Å, c = 14.3642(1) Å. Its structure can be described as made up of infinite (PO 3 ) 1− chains connected by FeO 6 octahedra, while the monovalent Na cations are located in the tunnels determined by the connection of PO 4 tetrahedrons and FeO 6 octahedrons. Besides, the morphology, vibrational spectra, magnetic and sodium deinsertion/insertion properties of NaFe(PO 3 ) 3 compound are also presented and discussed here for the first time, which can provide more information about the physicochemical properties of this metaphosphate compound.
研究领域:
无机化学
·
材料科学
·
固体化学
·
电化学
·
能源材料
✓ 已验证
DOI
高影响因子
LANGMUIR
·
2021
·
IF 3.882
Feifei Yin,Pengcheng Hu,Yong-Hao Ma,Yongsheng Luo,Chu Wang,Wenyong Zhu,Xiaolin Lu
Regarding methods of process and use of carbon nanotubes (CNTs), solvents are generally employed to disperse or dissolve CNTs as a pretreatment or intermediate process step. This naturally imposes an essential issue on how CNTs and solvents interact with each other, which seems trivial, comparatively inconsequential, and might often be overlooked from the perspective of engineering scenarios. However, as a matter of fact, it is indeed a fascinating and significant topic. In this article, to investigate the interfacial properties of multiwalled CNTs (MWCNTs) exposed to widely utilized solvents, we applied sum frequency generation vibrational spectroscopy (SFG-VS) to probe solvent-wetted MWCNTs and proved that polar solvents can substantially alter the interfacial optical property of MWCNTs. First, the interfacial optical phonon vibrational modes were detected when MWCNTs were wetted by polar solvents, i.e., water and dimethylformamide (DMF), while such modes were inactive when the solvents were nonpolar, i.e., decalin and air. Second, the interfacial optical phonon vibration frequency displayed distinct dependence on surface defects of MWCNTs. Combining theoretical analysis with experimental verification, a valid conjecture with respect to surface phonon vibration activity for MWCNTs was proposed. This phenomenon of polar solvent-induced SFG activity may have the potential to find applications in optical detection and environmental sensing in the near future.
研究领域:
材料科学
·
物理化学
·
光谱学
✓ 已验证
DOI
高影响因子
SURFACE SCIENCE
·
2013
·
IF 1.838
Yong Fang,Bolin Li,Jincheng Yu,Jie Zhou,Xin Xu,Wei Shao,Xiaolin Lu
The molecular structures of an adhesion promoter , polybutadiene-modified epoxy (PBME) rubber at surfaces and buried interfaces with gold (Au) were studied using sum frequency generation (SFG) vibrational spectroscopy . The SFG spectra showed that the soft butadiene part of PBME can segregate to the surfaces and buried interfaces in two base formulations. This is consistent with its application as an adhesion promoter. For the first time, the orientation of the segregated vinyl methylene groups of PBME at the surface and buried interface was evaluated. We found that the vinyl methylene groups at the surface were highly tilted and twisted by quantitative analysis; while the vinyl methylene groups at the buried Au interface were highly tilted by qualitative estimation. Furthermore, this study confirms that the sandwiched-face-down experimental setup can be employed to study the buried interfaces. This could be developed into a standard way to probe the buried interfaces between the commercialized resins and metal substrates.
研究领域:
材料科学
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）