Probe Spectroscopy Research Articles

Impact of Surface Adsorption on DNA Structure and Stability: Implications for Environmental DNA Interactions with Iron Oxide Surfaces.

Environmental DNA (eDNA), i.e., DNA found in the environment, can interact with various geochemical surfaces, yet little is known about these interactions. Mineral surfaces may alter the structure, stability, and reactivity of eDNA, impacting the cycling of genetic information and the reliability of eDNA-based detection tools. Understanding how eDNA interacts with surfaces is crucial for predicting its fate in the environment. In this study, we examined the surface interaction and stability of herring testes DNA, a model system for eDNA, on two common iron oxide phases present in the environment: α-FeOOH (goethite) and α-Fe2O3 (hematite). Utilizing spectroscopic probes, including attenuated total reflection Fourier-transform infrared (ATR-FTIR) and UV-vis spectroscopy, we quantified the DNA adsorption capacity at pH 5 and determined its secondary structure. DNA adsorbed irreversibly at pH 5 and 25 °C, primarily through its phosphate groups, and retained the solution-phase B-form structure. However, the infrared data also indicated some distortion of the B-form likely due to additional interactions between nitrogenous bases when adsorbed on the α-Fe2O3 particle surfaces. The distortion in the double helical structure of adsorbed DNA on α-Fe2O3 led to a lower melting temperature (Tm) of 60 °C compared to 70 °C for DNA in solution. In contrast, DNA adsorbed on α-FeOOH melted at higher temperatures relative to solution-phase DNA and in two distinct phases. Upon testing adsorbed DNA stability at higher pH values, there were distinct differences between the two iron oxide phases. For α-FeOOH, nearly 50% of the DNA desorbed from the surface when the solution pH changed from 5 to 8, while less than 5% desorbed from α-Fe2O3 under the same conditions. Overall, these findings underscore the importance of mineral-specific eDNA-surface interactions and their role in adsorbed eDNA stability, in terms of DNA melting and the impact of solution-phase pH changes.

Neutral Phosphorus-Based Beryllium Scorpionate Complexes as Spectroscopic Probes for Base Strength and Electron Donation.

The synthesis and properties of tris(diisopropylphosphanylmethyl)phenylborate ([TP(iPr)]-) beryllium complexes [TP(iPr)]BeL with L = Cl, Br, I, CN, SCN, OCN, N3, and CF3SO3 are described. In these compounds, the 1JPBe NMR coupling constant can be used as a sensitive probe for the basicity and electron-donating properties of the L- anions in solution.

Aerosol Fluorescent Labeling via Probe Molecule Volatilization.

The physicochemical properties of aerosols, including hygroscopicity, phase state, pH, and viscosity, influence important processes ranging from virus transmission and pulmonary drug delivery to atmospheric light scattering and chemical reactivity. Despite their importance, measurements of these key properties in aerosols remain experimentally challenging due to small particle sizes and low mass densities in air. Fluorescence probe spectroscopy is one of the only analytical techniques that is capable of experimentally determining these properties in situ in a nondestructive and minimally perturbative manner. However, the application of fluorescence probe spectroscopy to important classes of aerosols including exhaled respiratory and ambient atmospheric aerosols has been limited due to a typical reliance on premixing the probe molecule with particle constituents prior to particle generation, which is not always possible. Here, a method for aerosol fluorescent labeling based on probe molecule volatilization is developed. The method is first applied to label model polyethylene glycol (PEG) aerosols with two different polarity-sensitive probes, Nile red and Prodan. The similarity of the relative humidity-dependent fluorescent emission of each probe between prelabeled and volatilized-probe PEG particles validated the methodology. A preliminary application of the technique to indicate the hygroscopicity of artificial saliva respiratory particles and model atmospheric secondary organic aerosol particles is demonstrated. The methodology developed here paves the way for future studies applying powerful fluorescent probe-based analytical techniques to study exhaled or natural aerosols for which fluorescent prelabeling is not possible.

Sensitivity analysis of bent sensing elements of the fiber probes for mid-IR spectroscopy

Sensitivity analysis of bent sensing elements of the fiber probes for mid-IR spectroscopy

Understanding the protein conformation transition within polymer hydrogels using a near-infrared water spectroscopy probe

Understanding the protein conformation transition within polymer hydrogels using a near-infrared water spectroscopy probe

Nanoparticle-protein interactions: Spectroscopic probing of the adsorption of serum albumin to graphene oxide‑gold nanocomplexes surfaces

Graphene oxide‑gold nanocomposites (GO-AuNCPs) are promising candidates in nanomedicine. They will inevitably bind with biomolecules such as serum albumin (SA) in the body while they enter the organism. The interaction between GO-AuNCPs and human serum albumin (HSA)/bovine serum albumin (BSA) were investigated by using multispectroscopic methods, elucidating the binding principles through molecular simulations. The results of ultraviolet-visible (UV–vis) absorption spectroscopy and steady-state fluorescence spectroscopy indicated that GO-AuNCPs interacted with HSA/BSA with different degrees of interaction. The binding of GO-AuNCPs and HSA/BSA was a spontaneous endothermic reaction, and the quenching mechanism is static quenching. The binding constant (Ka) value of BSA binding to GO-AuNCPs at the same temperature was greater than that for HSA, indicating a stronger affinity of BSA for GO-AuNCPs. Molecular simulation revealed that the binding sites of GO-AuNCPs on HSA/BSA were located within the slits of the subdomains IB and IIIA, rather than within any known binding regions. This significant finding was validated by using of site markers phenylbutazone (PB) and flufenamic acid (FA). Synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, and circular dichroism (CD) spectroscopy showed that the conformation of HSA/BSA was altered upon the addition of GO-AuNCPs, resulting in slight structural changes of tryptophan and tyrosine residues. Although the secondary structure of HSA/BSA was changed, the α-helix remained dominant. The results provide a theoretical and experimental foundation for developing of safe and effective nanomaterials, which is of great theoretical significance.

Single crystal zircon doped with europium and vanadium simultaneously in order to support intensive luminescence under UV-light

Crystals of zircon, ZrSiO4, doped with Eu and V simultaneously have been grown for the first time by the flux method. The use of both (Eu + V) has supported higher Eu3+ incorporation into zircon lattice and respective increase of luminescence intensity under UV-light (220 and 365 nm) in comparison with zircon doped with Eu3+ only. The irregular distribution of vanadium and appearance of blue color in some zones of crystal matrix have been observed and studied using optical and scanning electron microscopy, electron probe microanalysis, cathodoluminescence imaging and spectroscopy. Further research is proposed on study of valence states of vanadium in zircon lattice and possible improvement of synthesis conditions in order to avoid formation of blue color suppressing the luminescence.

(Invited) In Situ Measurements during ALD/ALE Processes

Atomic layer deposition (ALD) and atomic layer etching (ALE) provide exquisite control over the addition and removal of thin film materials and are invaluable tools for semiconductor manufacturing and a wide range of other applications. However, it is not always clear why some ALD/ALE processes succeed while others fail. Performing in situ measurements during ALD/ALE can unravel the detailed surface chemistries underlying these processes to elucidate the reaction mechanisms and ultimately yield more robust and reliable processes. In this presentation, I will motivate the need for in situ measurements during ALD/ALE and provide detailed examples of the techniques used under typical ALD conditions including quartz crystal microbalance, mass spectrometry, infrared spectroscopy, spectroscopic ellipsometry, and optical emission spectroscopy for plasma-based processes. I will also describe some of the high vacuum in situ methods that have been exploited such as X-ray photoelectron spectroscopy and scanning probe microscopy. In addition, I will discuss synchrotron X-ray based methods for in situ study of ALD/ALE reactions.

Real-Time In Situ Tracking of the Penetration and Uptake Behavior of Nano-pesticides in Tea Plants Using Surface-Enhanced Raman Spectroscopy.

In situ monitoring of the uptake and transportation process of nano-pesticides during crop growth remains challenging thus far. In this report, the different three sizes of surface-enhanced Raman spectroscopy probes of nano-pesticides loaded with ferbam and acetamiprid are representative non-systemic or systemic pesticides, respectively. The probes were verified to have strong signals of the Raman spectrum enhancement effect. They were further applied on the leaves and roots of tea plants. Within 5 h, the nano-pesticides of 50 nm and 100 nm except 150 nm probes could rapidly penetrate young tea leaves to a depth of about 150-290 μm. Whereas none of the probes were observed to penetrate mature leaves and roots of tea plants. The result showed that the penetration rate depended on the size of the nano-pesticides and the structure or maturity of the plant tissue rather than the loaded pesticides. The penetration rate of small-sized nano-pesticides in young tea leaves is the fastest.

Comparison of Different Vibrational Spectroscopic Probes (ATR-FTIR, O-PTIR, Micro-Raman, and AFM-IR) of Lipids and Other Compounds Found in Environmental Samples: Case Study of Substrate-Deposited Sea Spray Aerosols

Comparison of Different Vibrational Spectroscopic Probes (ATR-FTIR, O-PTIR, Micro-Raman, and AFM-IR) of Lipids and Other Compounds Found in Environmental Samples: Case Study of Substrate-Deposited Sea Spray Aerosols

Effects of Al Substitution for Fe in Na₅FeSi₄O₁₂ (5.1.8) Glasses: Structure and Crystallization

In this study, the effects of substituting Al for Fe in 5Na2O∙(Al2O3)x∙(Fe2O3)1-x∙8SiO2 glass, x=0 to 1, and Na5AlxFe1-xSi4O12 (5.1.8) crystal, were investigated using thermal analysis, Fe K-edge X-ray absorption, X-ray diffraction, Raman spectroscopy, and Electron Probe Microanalysis. In both glass and crystallized glass, nearly all the Fe was tetrahedrally coordinated Fe3+, as expected from the high concentration of Na2O. The substitution of Al for Fe in the glasses caused the glass transition temperature to increase as polymerization increased, as evidenced by Raman, likely due to both field strength differences of Al vs Fe and a small amount of Fe2+ network modifier present with Fe. After heat treatment at 700 °C for 24 hours, the glasses had crystallized, forming Na2SiO3 and NaAlSiO4 in compositions with high Al concentrations and the 5.1.8 crystal in compositions with high Fe concentrations. Through electron microprobe, it was determined that <0.04 formula unit Al incorporated into the 5.1.8 crystal, i.e. Na5Fe0.96Al0.04Si4O12. The 5.1.8 crystal only formed when Fe concentration was higher than Al in the starting glass.

Experimental investigation on high heat flux plasma parameters of HIT-PSI device in argon discharges

Abstract Researches on plasma-facing materials/components (PFMs/PFCs) have become a focus in magnetic confinement fusion studies, particularly for advanced tokamak operation scenarios. Similarly, spacecraft surface materials must maintain stable performance under relatively high temperatures and other harsh plasma conditions, making studies of their thermal and ablation resistance critical. Recently, a low-cost, low-energy-storage for superconducting magnets, and compact linear device, HIT-PSI, has been designed and constructed at Harbin Institute of Technology (HIT) to investigate the interaction between stable high heat flux plasma and PFMs/PFCs in scrape-off-layer (SOL) and divertor regions, as well as spacecraft surface materials. The parameters of the argon plasma beam of HIT-PSI are diagnosed using a water-cooled planar Langmuir probe and emission spectroscopy. As magnetic field rises to 2 T, the argon plasma beam generated by a cascaded arc source achieves high density exceeding 1.2×1021 m−3 at a distance of 25 cm from the source with electron temperature surpassing 4 eV, where the particle flux reaches 1024 m−2s−1, and the heat flux loaded on the graphite target measured by infrared camera reaches 4 MW/m2. Combined with probe and emission spectroscopy data, the transport characteristics of the argon plasma beam are analyzed.

Ultrafast terahertz conductivity in epitaxial graphene nanoribbons: an interplay between photoexcited and secondary hot carriers

Abstract Optical pump-terahertz probe spectroscopy has been used to investigate ultrafast photo-induced charge carrier transport in 3.4 µm wide graphene ribbons upon scaling the optical pump intensity. For low pump fluences, the deposited pump energy is rapidly redistributed through carrier–carrier scattering, producing secondary hot carriers: the picosecond THz photoconductivity then acquires a negative sign and scales linearly with an increasing pump fluence. At higher fluences, there are not enough equilibrium carriers able to accept the deposited energy, directly generated (excess) carriers start to contribute significantly to the photoconductivity with a positive sign leading to its saturation behavior. This leads to a non-monotonic variation of the carrier mobility and plasmonic resonance frequency as a function of the pump fluence and, at high fluences, to a balance between a decreasing carrier scattering time and an increasing Drude weight. In addition, a weak carrier localization observed for the polarization parallel to the ribbons at low pump fluences is progressively lifted upon increasing the pump fluence as a result of the rise of initial carrier temperature.

Low temperature exciton lifetime enhancement of MAPbBr3 studied by broadband terahertz spectroscopy

Over the past few years, lead halide perovskites have demonstrated significant potential in the field of solar cells, light-emitting diodes, and field-effect transistors. We investigated the transient photoconductivity and temperature-induced phase transitions in MAPbBr3 thin films, using ultrabroadband optical pump-terahertz probe spectroscopy with varying excitation fluences and temperature conditions. As the temperature drops from 293 to 123 K, MAPbBr3 undergoes two phase transitions, resulting in a significant extension of exciton lifetime in the tetragonal phase near 150 K, where MAPbBr3 exhibits a longer exciton lifetime. Our research contributes to a better understanding of the temperature-induced phase transition mechanism of MAPbBr3, enhancing its potential applications in optoelectronic devices.

Spectroscopic Investigation of the Interaction of Silicate Ions with Lead Carbonates Under Drinking Water Conditions.

The presence of lead has been identified as a critical health risk in drinking water systems serviced by Pb-bearing plumbing. Among several corrosion control strategies, the use of sodium silicates has attracted interest due to the advantages it offers compared to other approaches, such as phosphate dosage. However, the interaction of silicate ions with lead corrosion scales and other ubiquitous dissolved species such as Al ions in drinking water is not well understood. In this work, surface and bulk spectroscopic analysis of the solid scale is combined with quantitative analysis of the aqueous phase. A detailed spectroscopic probing of the transformations taking place on the solid phase enables us to develop a mechanistic framework for reports published in the last four years in the open literature, suggesting that silicates may not be an adequate corrosion control option in drinking water systems rich in solid lead carbonates. The spectroscopic data obtained demonstrate that in the presence of chlorine residual, silicates inhibit Pb(II) carbonates from oxidizing into less soluble Pb(IV) oxides thus, negatively impacting water quality. Furthermore, aluminum ions interact with silicates resulting in the formation of solid allophane phase over the lead scale surface, extending into the bulk. However, the formation of this new solid allophane phase does not protect against lead dissolution.

A Spectroscopic Study on the Amyloid-β Interaction with Clicked Peptide-Porphyrin Conjugates: a Vision Toward the Detection of Aβ Peptides in Aqueous Solution.

Alzheimer's disease (AD) is a multifactorial form of dementia mainly affecting people in the elderly, but no effective cure is available. According to the amyloid hypothesis the aggregation of Amyloid-β (Aβ) into oligomeric toxic species is believed to concur with the onset and progression of the disease heavily. By using a click chemistry approach, we conjugated a suitable designed peptide sequence to a metalloporphyrin moiety to obtain three hybrid peptide systems to be studied for their interaction with Amyloid-β peptides. The aim is to get new tools for the diagnosis and therapy in AD. The results described in this study, which were obtained through spectroscopic techniques (UV-Vis, CD, bis-Ans and intrinsic porphyrin Fluorescence), Microfluidics (GCI) and cell biology (MTT, Live cell imaging and flow cytometry), reveal interesting features about the structure-activity relationships connecting these conjugates with the interaction with Aβ, as well as on their potential use as sensing systems. In our opinion the data reported in this paper make the porphyrin-peptide conjugates highly compelling for further exploration as spectroscopic probes to detect Aβ biomarkers in biological fluids.

Witnessing Entanglement and Quantum Correlations in Condensed Matter: A Review

AbstractThe detection and certification of entanglement and quantum correlations in materials is of fundamental and far‐reaching importance, and has seen significant recent progress. It impacts both the understanding of the basic science of quantum many‐body phenomena as well as the identification of systems suitable for novel technologies. Frameworks suitable to condensed matter that connect measurements to entanglement and coherence have been developed in the context of quantum information theory. These take the form of entanglement witnesses and quantum correlation measures.The underlying theory of these quantities, their relation to condensed matter experimental techniques, and their application to real materials are comprehensively reviewed. In addition, their usage in, e.g., protocols, the relative advantages and disadvantages of witnesses and measures, and future prospects in, e.g., correlated electrons, entanglement dynamics, and entangled spectroscopic probes, are presented. Consideration is given to the interdisciplinary nature of this emerging research and substantial ongoing progress by providing an accessible and practical treatment from fundamentals to application. Particular emphasis is placed on quantities accessible to collective measurements, including by susceptibility and spectroscopic techniques. This includes the magnetic susceptibility witness, one‐tangle, concurrence and two‐tangle, two‐site quantum discord, and quantum coherence measures such as the quantum Fisher information.

The First Combined Hα and Rest-UV Spectroscopic Probe of Galactic Outflows at High Redshift

We investigate the multiphase structure of gas flows in galaxies. We study 80 galaxies during the epoch of peak star formation (1.4 ≤ z ≤ 2.7) using data from the Keck/Low-Resolution Imaging Spectrometer (LRIS) and the Very Large Telescope/K-Band Multi-Object Spectrograph (KMOS). Our analysis provides a simultaneous probe of outflows using UV emission and absorption features and Hα emission. With this unprecedented data set, we examine the properties of gas flows estimated from LRIS and KMOS in relation to other galaxy properties, such as star formation rate (SFR), SFR surface density (ΣSFR), stellar mass (M *), and main-sequence offset (ΔMS). We find no strong correlations between outflow velocity measured from rest-UV line centroids and galaxy properties. However, we find that galaxies with detected outflows show higher averages in SFR, ΣSFR, and ΔMS than those lacking outflow detections, indicating a connection between outflow and galaxy properties. Furthermore, we find a lower average outflow velocity than previously reported, suggesting greater absorption at the systemic redshift of the galaxy. Finally, we detect outflows in 49% of our LRIS sample and 30% in the KMOS sample and find no significant correlation between outflow detection and inclination. These results may indicate that outflows are not collimated and that Hα outflows have a lower covering fraction than low-ionization interstellar absorption lines. Additionally, these tracers may be sensitive to different physical scales of outflow activity. A larger sample size with a wider dynamic range in galaxy properties is needed to further test this picture.

A compact inertial nanopositioner operating at cryogenic temperatures.

Nano-positioning plays a very important role in applications such as scanning probe microscopy and optics. We report the development of a compact inertial nanopositioner along with fully computer interfaced electronics operating down to 2K and its use in our fully automated needle-anvil type Point Contact Andreev Reflection (PCAR) apparatus. We also present the fully automated operational procedures using the LabVIEW interface with our home-built electronics. The point contact spectroscopy probe has been successfully used to perform PCAR measurements on elemental superconductors at low temperatures. The small footprint of our nanopositioner makes it ideally suited for incorporation in low temperature scanning probe microscopes and makes this design versatile for various research and industrial purposes.

Investigation on the Surface Properties of Annealed Copper Selenide Thin Films with Various Compositional Ratios

Copper‐based metal chalcogenides are versatile materials used for a variety of electronic devices, yet realizing the full scope of copper‐based composite materials is hindered by limited understanding of their chemical properties. In this work, copper selenide thin films (TFs) are fabricated using radio frequency (RF) magnetron co‐sputtering to investigate the effects of composition and annealing temperature on the films. The surface composition of the TFs is examined using energy dispersive X‐Ray spectroscopy (EDS) and X‐Ray photoelectron spectroscopy (XPS). In the unannealed films, an increase in Se composition leads to smaller grain sizes and smoother surfaces. The influence of higher Se content on the dispersive surface free energy (SFE) is shown through contact angle measurements. Work functions (WFs), determined by Kelvin probe (KP) and ultraviolet photoelectron spectroscopy (UPS), rose with increasing Se content. After annealing, the TFs exhibited opposite trends. As the films transitioned from an amorphous to a crystalline phase due to annealing, their roughness significantly increased.