Scattering Spectroscopy Research Articles

Ion Dynamics in Ionic-Liquid-Based Li-Ion Electrolytes Investigated by Neutron Scattering and Dielectric Spectroscopy.

A detailed understanding of the diffusion mechanisms of ions in pure and doped ionic liquids remains an important aspect in the design of new ionic-liquid electrolytes for energy storage. To gain more insight into the widely used imidazolium-based ionic liquids, the relationship between viscosity, ionic conductivity, diffusion coefficients, and reorientational dynamics in the ionic liquid 3-methyl-1-methylimidazolium bis(trifluoromethanesulfonyl)imide (DMIM-TFSI) with and without lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) was examined. The diffusion coefficients for the DMIM+ cation and the role of ion aggregates were investigated by using the quasielastic neutron scattering (QENS) and neutron spin echo techniques. Two diffusion mechanisms are observed for the DMIM+ cation with and without Li-TFSI, that is, translational and local. The data additionally suggest that Li+ ion transport along with ion aggregates, known as the vehicle mechanism, may play a significant role in the ion diffusion process. These dielectric-spectroscopy investigations in a broad temperature and frequency range reveal a typical α-β-relaxation scenario. The α relaxation mirrors the glassy freezing of the dipolar ions, and the β relaxation exhibits the signatures of a Johari-Goldstein relaxation. In contrast to the translational mode detected by neutron scattering, arising from the decoupled faster motion of the DMIM+ ions, the α relaxation is well coupled to the dc charge transport, that is, the average translational motion of all three ion species in the material. The local diffusion process detected by QENS is only weakly dependent on temperature and viscosity and can be ascribed to the typical fast dynamics of glass-forming liquids.

Modifications of the optical properties of quantum dots on liposome encapsulation for applications in theranostic liposomes

Semiconductor quantum dots have been extensively used for biomedical applications as efficient biomarkers. At the same time, liposome encapsulation may open other applications of QDs: the possibility of liposome labeling to stimulate the pathway to specific organs as efficient and specific biomarkers. Due to this, the optical properties of QDs after liposomal encapsulation are very important to many applications, for example, in biosensors or theranostic liposomes. The commercial-acquired CdSe/ZnS core/shell quantum dots of two different emission wavelengths (530 and 640 nm) were encapsulated in lecithin liposomes, and characterized by Atomic Force Microscopy, Transmission Electron Microscopy, Dynamic Light Scattering, Photoluminescence, and Raman Spectroscopy. The important changes in optical properties at liposome encapsulation of the studied QDs are demonstrated and discussed.

Robust, flexible, sticky and high sensitive SERS membrane for rapid detection applications

Up to date, many efforts have been done to improve the performance of surface-enhanced Raman scattering spectroscopy (SERS) substrates, but the fabrication of a stable, sensitive and uniform SERS substrate in a simple way also remains a challenge. In this work, we report a very convenient way to prepare a durable, uniform, flexible and sticky SERS substrate by dropping noble metal nanoparticles colloids on highly transparent fluorescent quantitative PCR sealing membranes, designated as HTFQ-PCR-M. HTFQ-PCR-M based SERS substrate exhibits high sensitivity, superior reproducibility, good stability and thermal stability. We apply such to directly collect thiram pesticide residues on the peel of fruit and do Raman measurement, to analyze dividually methylene blue and rhodamine B in mixture by the aid of thin layer chromatography plate via “paste and peel off” approach. Moreover, HTFQ-PCR-M based SERS substrate can keep its SERS activity at 90℃. As a perspective, HTFQ-PCR-M based SERS substrate could offer a great practical potential for on-spot identification of trace target molecules in various real samples.

Nature of the Debye-Process in Monohydroxy Alcohols: 5-Methyl-2-Hexanol Investigated by Depolarized Light Scattering and Dielectric Spectroscopy.

The slow Debye-like relaxation in the dielectric spectra of monohydroxy alcohols is a matter of long-standing debate. In the present Letter, we probe reorientational dynamics of 5-methyl-2-hexanol with dielectric spectroscopy and depolarized dynamic light scattering (DDLS) in the supercooled regime. While in a previous study of a primary alcohol no indication of the Debye peak in the DDLS spectra was found, we now for the first time report clear evidence of a Debye contribution in a monoalcohol in DDLS. A quantitative comparison between the dielectric and DDLS manifestation of the Debye peak reveals that while the dielectric Debye process represents fluctuations in the end-to-end vector dipole moment of the transient chains, its occurrence in DDLS shows a more local signature and is related to residual correlations that occur due to a slight anisotropy of the α relaxation caused by the chain formation.

Yi‐Tao Long

Angewandte Chemie International EditionVolume 57, Issue 45 p. 14682-14682 Author ProfileFree Access Yi-Tao Long First published: 10 July 2018 https://doi.org/10.1002/anie.201806950AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract “My favorite food is tiger prawn. The most important thing I learned from my parents is persistence …” Find out more about Yi-Tao Long in his Author Profile. Yi-Tao Long The author presented on this page has published more than 10 articles in Angewandte Chemie in the last 10 years, most recently: “Single-Nanoparticle Photoelectrochemistry at a Nanoparticulate TiO2-Filmed Ultramicroelectrode”: Y.-Y. Peng, H. Ma, W. Ma, Y.-T. Long, H. Tian, Angew. Chem. Int. Ed. 2018, 57, 3758; Angew. Chem. 2018, 130, 3820. The work of Y.-T. Long has been featured on the inside back cover of Angewandte Chemie: “Electrodeposition of Single-Metal Nanoparticles on Stable Protein 1 Membranes: Application of Plasmonic Sensing by Single Nanoparticles”: L.-X. Qin, Y. Li, D.-W. Li, C. Jing, B.-Q. Chen, W. Ma, A. Heyman, O. Shoseyov, I. Willner, H. Tian, Y.-T. Long, Angew. Chem. Int. Ed. 2012, 51, 140; Angew. Chem. 2012, 124, 144. Date of birth: July 27, 1967 Position: Cheung Kong Professor, School of Chemistry and Molecular Engineering, East China University of Science and Technology E-mail: ytlong@ecust.edu.cn Homepage: http://ytlong.ecust.edu.cn/ ORCID: 0000-0003-2571-7457 Education: 1989 BSc, Shandong University 1996 MSc, Nanjing University 1999 PhD with Professor Hong-Yuan Chen, Nanjing University 1999–2001 Postdoctoral fellow with Professor Michael Grunze, University of Heidelberg 2001 Research associate, École Nationale Supérieure de Chimie de Paris 2001–2005, HSURC Fellow/research associate with Professors Heinz-Bernhard Kraatz and Jeremy S. Lee, University of Saskatchewan 2006 Research associate with Professor Chris Backhouse, University of Alberta 2006–2007 Associate specialist with Professors Luke P. Lee and Gabor Somorjai, University of California, Berkeley Awards: 2016 First Prize, Shanghai Natural Science Award; 2017 Grand Prize, Science and Technology Award, China Association for Instrumental Analysis Research: Electroanalytical chemistry; nanopores; nanoplasmonic sensing; single-molecule analysis Hobbies: Drinking tea, traveling My favorite food is tiger prawn. The most important thing I learned from my parents is persistence. My favorite place on earth is Shanghai. If I were not a scientist, I would be a painter. The most exciting thing about my research is to simplify the sophisticated. The best advice I have ever been given is “God rewards the diligent” (天道酬勤). I celebrate success by drinking a cup of tea. My favorite book (fiction) is The Mysterious Island by Jules Verne. My top three films of all time are The Man with the Golden Gun, Goldfinger, and Goldeneye. The downside of my job is spending too little time with my family. My favorite type of music is Peking opera. The most significant scientific advance of the last 100 years has been elucidating the nature of the chemical bond. My 5 top papers: 1“Self-assembling bacterial pores as components of nanobiosensors for the detection of single peptide molecules”: Y.-T. Long, M.-N. Zhang, Science in China Series B: Chemistry 2009, 52, 731. (Electrochemical nanopore confinement for single-peptide sensing.) 2“Single Gold Nanoparticles as Real-Time Optical Probes for the Detection of NADH-Dependent Intracellular Metabolic Enzymatic Pathways”: L. Zhang, Y. Li, D. Li, C. Jing, X. Chen, M. Lv, Q. Huang, Y.-T. Long, I. Willner, Angew. Chem. Int. Ed. 2011, 50, 6789; Angew. Chem. 2011, 123, 6921. (Established a method based on single plasmonic nanoparticles for single-cell analysis.) 3“Plasmon Resonance Scattering Spectroscopy at the Single-Nanoparticle Level: Real-Time Monitoring of a Click Reaction”: L. Shi, C. Jing, W. Ma, D.-W. Li, J. E. Halls, F. Marken, Y.-T. Long, Angew. Chem. Int. Ed. 2013, 52, 6011; Angew. Chem. 2013, 125, 6127. (Monitoring a click reaction at the single-nanoparticle level.) 4“Nanopore-Based Sequencing and Detection of Nucleic Acids”: Y.-L. Ying, J. Zhang, R. Gao, Y.-T. Long, Angew. Chem. Int. Ed. 2013, 52, 13154; Angew. Chem. 2013, 125, 13392. (Progress in the field of nanopores, including pore-forming materials, sensing mechanisms, advanced instruments, and big data processing methods.) 5“Discrimination of oligonucleotides of different lengths with a wild-type aerolysin nanopore”: C. Cao, Y.-L. Ying, Z.-L. Hu, D.-F. Liao, H. Tian, Y.-T. Long, Nat. Nanotechnol. 2016, 11, 713. (Discovering the unique sensing ability of the aerolysin nanopore.) Volume57, Issue45November 5, 2018Pages 14682-14682 ReferencesRelatedInformation

1.5 GPa compact double-wall clamp cell for SANS and NSE studies at low temperatures and high magnetic fields

We have developed and realised a compact high-pressure clamp cell of the piston-cylinder type for Small Angle Neutron Scattering (SANS) and Neutron Spin Echo (NSE) spectroscopy measurements. The cell can pressurise φ5 mm samples up to 1.5 GPa. It is non-magnetic, produces a sufficiently low and flat SANS background with a relatively good neutron transmission and can be used in combination with polarised neutrons. The cell accommodates samples of up to 55 mm3 in volume and adopts a two-layer geometry: a TiZr body (outer layer) and a CuBe2 insert (inner layer). Its design is very compact and can be employed inside cryomagnets featuring a sample bore greater than φ30 mm. We present the cell and illustrate its performances with a series of neutron scattering experiments performed on single-crystalline MnSi.

From Fundamental toward Applied SERS: Shared Principles and Divergent Approaches

AbstractOver more than 40 years since its discovery, surface‐enhanced Raman scattering/spectroscopy (SERS) has attracted substantial attention as a tool for fundamental research in surface science and for potential analytical sensing applications. This review aims to concisely summarize the essential principles of both the physical and chemical processes underlying Raman signal enhancement, as well as elements of the broader field of plasmonics that are most relevant to SERS. In order to make sense of the overwhelming variety of SERS platforms that are reported, the fabrication, properties, and operational principles of enhancing substrates are given particular attention here in the context of specific application requirements. While the high spatial precision of lithographic techniques has helped to improve the understanding of plasmonic platforms, their prohibitive cost has encouraged the exploration of more facile fabrication methods for more widespread adoption of SERS. Selected examples are introduced to illustrate common themes that recur in fundamental studies, analytical applications, and efforts to produce stable, affordable, and robust SERS sensing platforms.

Phonon Lifetime Observation in Epitaxial ScN Film with Inelastic X-Ray Scattering Spectroscopy.

Phonon-phonon scattering dominates the thermal properties in nonmetallic materials, and it directly influences device performance in applications. The understanding of the scattering has been progressing using computational approaches, and the direct and systematic observation of phonon modes that include momentum dependences is desirable. We report experimental data on the phonon dispersion curves and lifetimes in an epitaxially grown ScN film using inelastic x-ray scattering measurements. The momentum dependence of the optical phonon lifetimes is estimated from the spectral width, and the highest-energy phonon mode around the zone center is found to possess a short lifetime of 0.21ps. A comparison with first-principles calculations shows that our observed phonon lifetimes are quantitatively explained by three-body phonon-phonon interactions.

Photochromic Properties and Surface Enhanced Raman Scattering Spectra of Indoline Spiropyran in Silver-Based Nanocomposite Films

The structure and photochromic transformations of composite organometallic nanosystems composed of Ag nanoparticles covered with a layer of indoline-spiropyran (ISP) molecules from solutions were studied by spectrophotometry, surface Raman scattering spectroscopy (SERS) and quantum chemistry. Analysis of experimental data showed that studied nanostructured systems have photochromic properties, manifested in the reversible photo-induced changes both of the electronic-absorption spectra and of the relative intensity of the SERS bands. The open form of ISP, formed in the organometallic nanostructured film as a result of photochromic transformations, has an adsorption geometry, and, possibly, a conformation different from that formed as a result of chemisorption of ISP molecules on silver colloids.

The synovial fluid analysis by using Raman Scattering spectroscopy in order to educe the synovial joint pathology

In this paper, we present the results of experimental studies by using Raman-scattering spectroscopy method of synovial fluid that was obtained from the joint cavity during the surgery. Analyzing the composition of synovial fluid, it was identified that with the progress of degenerative-dystrophic process in synovial fluid of the affected joint, the gross amount of components increases at wave numbers: 1155 cm-1 (hyaluronic acid (C-O, C-C )) and 1250cm-1(Amide III). The entered optical numbers allow us to characterize synovial fluid (SF) in osteoarthrosis (OA). This specific Raman-scattering spectroscopy method may become a new diagnostic screening in order to educe the synovial joint pathology.

Novel Cationic Polyurethane Surfactants Containing Saturated Chains- Part 1: Synthesis, Characterization and Surface Activity

Novel cationic polymeric surfactants were synthesized throughout the reaction of monoester of triethanol amine and two saturated fatty acids (palmitic acid and stearic acid) and TDI (toluene diisocyanate). The obtained polyurethane (PU) then was reacted by acetyl chloride to yield the desired surfactants. The structures of the produced compounds were described by using Fourier Transform Infrared Spectroscopy (FTIR) and their average molecular weights. Silver nanocomposite of the prepared cationic PU surfactants were characterized via physical combination by chemically prepared silver nanoparticles. The structure of the silver composite was determined using: Ultra-violet spectroscopy, Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS) spectroscopy. The effect of the hydrophobic chains on the surface activities of the synthesized cationic polymeric surface active agents and their silver nanocomposite was studied.

Molecular association of small amphiphiles: Origin of ionic liquid properties in dibutyl phosphate/propylamine binary mixtures

Binary mixtures of liquid surfactants, owing to the amphiphilic nature of the molecules involved, can exhibit nano-segregation and peculiar transport properties. The amphiphilicity, and consequently the resulting self-assembly, can be tuned by changing the length of the alkyl chains and the nature of the polar head group. So, in the present study, the structural and dynamic properties of dibutyl phosphate/propylamine liquid mixtures at various compositions have been investigated by Wide Angle X-ray Scattering (WAXS), FT-IR, rheometry and dielectric spectroscopy in order to study the intermolecular association taking place when alkylphosphates and alkylamines with a small apolar part are mixed together. It was found that a proton transfer from the dibutyl phosphate PO4H group to the propilamine NH2 one takes place, due to the acidic and basic nature of the two molecules involved. This triggers the formation of charged species and an intermolecular association typical of ionic liquid systems and causing an increase in viscosity of two orders of magnitude with respect to the two pure components. Effects due to the different amine isomers have been highlighted since the steric hindrance of the amine alkyl chain can significantly contribute to the molecular slippage thus affecting the overall mixture viscosity. Surprising dielectric properties have also been observed at a specific composition: a strikingly enhanced proton conductivity and a negative value of the dielectric constant in the MHz frequency range, as a result of the local self-assembly and the competition between the mechanism of jump of “free” protons among neighboring polar headgroups and the molecularly-assisted mechanism of charge transport. This work shows news potentialities of such systems as specialized solvent media and proton conducting water-free organic-based liquid systems and, from a more general prospect, the comprehension of the molecular mechanism involved in their transport properties is pivotal for the piloted design of smart materials for specific applications.

Hydrogen Bond Dynamics of Cellulose through Inelastic Neutron Scattering Spectroscopy.

This work explores the dynamics of hydrogen bond networks in cellulose through inelastic neutron scattering (INS) and periodic CASTEP calculations. Estimated spectra were based on the crystal structure of cellulose Iα and Iβ and replicate the INS spectrum of cellulose samples with remarkable similarity, allowing a reliable assignment of INS bands to vibrational modes of cellulose. Comparison of cellulose samples from varied sources, from bacterial to kraft pulp, allows the identification of characteristic INS bands, arising from C2-OH torsional motions, which easily identify which allomorph-Iα or Iβ-is prevalent. A high crystallinity index is revealed by the presence of well-defined INS bands associated with highly cooperative CH bending modes along the chain. Hydrating kraft cellulose samples clearly affects those INS bands related with the hydroxymethyl group, identified as the preferred binding site for water molecules. At high humidity content level, a significant proportion of the water molecules is aggregated in clusters within the amorphous cellulose domains. The formation of ice microcrystals leads to a partial disruption of the hydrogen-bond network, as can be concluded from the observed red-shift of the torsional OH vibrational modes. The full assignment and interpretation of cellulose's INS spectra herein provided is a sound basis for future use of INS spectroscopy in the characterization of functionalized cellulose fibers and composite materials.

Nature of Local Symmetry Violations of Ions in the Magnetic Subsystem of Magnetoplumbite Crystal, According to Raman Scattering Spectroscopy Data

The structure of an M-type lead hexaferrite (magnetoplumbite) crystal is studied via the diffraction of synchrotron radiation. The crystal model contains two iron ions positions with dynamic disorder. The dynamics of the crystal lattice in the temperature range of 80 to 775 K is studied by Raman scattering. Particular attention is given to the discussing the nature of the local disorder of iron ions in the trigonal bipyramidal environment of oxygen ions.

Nonlinear spin conductance of yttrium iron garnet thin films driven by large spin-orbit torque

We report a study on spin conductance in ultra-thin films of Yttrium Iron Garnet (YIG), where spin transport is provided by propagating spin waves, that are generated and detected by direct and inverse spin Hall effects in two Pt wires deposited on top. While at low current the spin conductance is dominated by transport of thermal magnons, at high current, the spin conductance is dominated by low-damping non-equilibrium magnons thermalized near the spectral bottom by magnon-magnon interaction, with consequent a sensitivity to the applied magnetic field and a longer decay length. This picture is supported by microfocus Brillouin Light Scattering spectroscopy.

Surface-Enhanced Raman Spectroscopy of Carbon Nanomembranes from Aromatic Self-Assembled Monolayers.

Surface-enhanced Raman scattering spectroscopy (SERS) was employed to investigate the formation of self-assembled monolayers (SAMs) of biphenylthiol, 4'-nitro-1,1'-biphenyl-4-thiol, and p-terphenylthiol on Au surfaces and their structural transformations into carbon nanomembranes (CNMs) induced by electron irradiation. The high sensitivity of SERS allows us to identify two types of Raman scattering in electron-irradiated SAMs: (1) Raman-active sites exhibit similar bands as those of pristine SAMs in the fingerprint spectral region, but with indications of an amorphization process and (2) Raman-inactive sites show almost no Raman-scattering signals, except a very weak and broad D band, indicating a lack of structural order but for the presence of graphitic domains. Statistical analysis showed that the ratio of the number of Raman-active sites to the total number of measurement sites decreases exponentially with increasing the electron irradiation dose. The maximum degree of cross-linking ranged from 97 to 99% for the three SAMs. Proof-of-concept experiments were conducted to demonstrate potential applications of Raman-inactive CNMs as a supporting membrane for Raman analysis.

Study on the Elastic Properties and the Phase Transition Behavior of Condensed Matter by Using Brillouin Light Scattering Spectroscopy

Study on the Elastic Properties and the Phase Transition Behavior of Condensed Matter by Using Brillouin Light Scattering Spectroscopy

Disclosure of the Surface Composition of TiO2-Supported Gold–Palladium Bimetallic Catalysts by High-Sensitivity Low-Energy Ion Scattering Spectroscopy

It is well-known that there is a critical relationship between the surface composition and activity for a bimetallic catalyst. However, the surface is normally reconstructed under different conditions, which makes the surface more complicated. In this work, TiO2-supported colloidal PdxAuy-NPs with different atomic ratios were prepared and treated under oxidation, reduction, and actual catalytic reaction conditions. The surface composition and structure were measured using X-ray photoelectron spectroscopy (XPS) and high-sensitivity low-energy ion scattering spectroscopy (HS-LEIS). Phase diagrams of the surface compositions under various conditions as a function of the bulk composition were established. Oxidation induces dealloying and enrichment of PdO on the surface, while H2 reduction results in realloying with just slight surface enrichment of Pd. Gold helps Pd to resist oxidation and enhances its activity for CO oxidation at low temperature.

The Critical Role of Thioacetamide Concentration in the Formation of ZnO/ZnS Heterostructures by Sol-Gel Process.

ZnO/ZnS heterostructures have emerged as an attractive approach for tailoring the properties of particles comprising these semiconductors. They can be synthesized using low temperature sol-gel routes. The present work yields insight into the mechanisms involved in the formation of ZnO/ZnS nanostructures. ZnO colloidal suspensions, prepared by hydrolysis and condensation of a Zn acetate precursor solution, were allowed to react with an ethanolic thioacetamide solution (TAA) as sulfur source. The reactions were monitored in situ by Small Angle X-ray Scattering (SAXS) and UV-vis spectroscopy, and the final colloidal suspensions were characterized by High Resolution Transmission Electron Microscopy (HRTEM). The powders extracted at the end of the reactions were analyzed by X-ray Absorption spectroscopy (XAS) and X-ray diffraction (XRD). Depending on TAA concentration, different nanostructures were revealed. ZnO and ZnS phases were mainly obtained at low and high TAA concentrations, respectively. At intermediate TAA concentrations, we evidenced the formation of ZnO/ZnS heterostructures. ZnS formation could take place via direct crystal growth involving Zn ions remaining in solution and S ions provided by TAA and/or chemical conversion of ZnO to ZnS. The combination of all the characterization techniques was crucial to elucidate the reaction steps and the nature of the final products.

Plasmonic nanoparticle-based expansion microscopy with surface-enhanced Raman and dark-field spectroscopic imaging.

Fluorescence-based expansion microscopy (ExM) is a new technique which can yield nanoscale resolution of biological specimen on a conventional fluorescence microscope through physical sample expansion up to 20 times its original dimensions while preserving structural information. It however inherits known issues of fluorescence microscopy such as photostability and multiplexing capabilities, as well as an ExM-specific issue in signal intensity reduction due to a dilution effect after expansion. To address these issues, we propose using antigen-targeting plasmonic nanoparticle labels which can be imaged using surface-enhanced Raman scattering spectroscopy (SERS) and dark-field spectroscopy. We demonstrate that the nanoparticles enable multimodal imaging: bright-field, dark-field and SERS, with excellent photostability, contrast enhancement and brightness.