Excited Proton Research Articles

Scintillation properties of flexible scintillator composed on polydimethylsiloxane integrated with Lu2GdAl3Ga2O12:Pr2O3 phosphors

This study explored the luminescence properties and sensitivity of a flexible scintillator composed on polydimethylsiloxane integrated with Lu2GdAl3Ga2O12 doped with 1 mol% Pr2O3 phosphors. The flexible scintillator was fabricated using a molding technique. The luminescence properties were investigated under photo, proton, and X-ray excitation at room temperature. The scintillator exhibited sharp and narrow emission peaks attributed to f-f transitions, and a decay time of 14 μs. It demonstrated a sensitivity of 0.638 μC/R cm3 under an X-ray dose of 1.841 R. This study demonstrates a high performance flexible scintillator suitable for advanced radiation detection applications in medical imaging and safety monitoring.

Ab initio calculations of anomalous seniority breaking in the πg9/2 shell for the N = 50 isotones

We performed ab initio valence-space in-medium similarity renormalization group (VS-IMSRG) calculations based on chiral two-nucleon and three-nucleon interactions to investigate the anomalous seniority breaking in the neutron number N=50 isotones: 92Mo, 94Ru, 96Pd, and 98Cd. Our calculations well reproduced the measured low-lying spectra and electromagnetic E2 transitions in these nuclei, supporting partial seniority conservation in the first πg9/2 shell. Recent experiments have revealed that, compared to the symmetric patterns predicted under the conserved seniority symmetry, the 41+→21+E2 transition strength in 94Ru is significantly enhanced and that in 96Pd is suppressed. In contrast, the 61+→41+ and 81+→61+ transitions exhibit the opposite trend. We found that this anomalous asymmetry is sensitive to subtle seniority breaking effects, providing a stringent test for state-of-the-art nucleon-nucleon interactions and nuclear models. We analyzed the anomalous asymmetry using VS-IMSRG calculations across various valence spaces. Our ab initio results suggest that core excitations of both proton and neutron across the Z=50 shell are ascribed to the observed anomalous seniority breaking in the N=50 isotones.

Biomass-derived multiatom-doped carbon dots for water sensing based on excited state intraparticle proton transfer in organic solvents

The presence of trace water impurities in organic solvents can significantly influence chemical reactions and product quality; thus, the accurate detection of water content in these solvents is a critical requirement for industrial applications. Accordingly, an eco-friendly, effective, and economical sensor for detecting trace quantities of miscible water in organic solvents is required for industrial applications. In this study, we synthesized biomass-derived multi-atom-doped carbon dots (MACDs) as fluorescent probes and employed them for the detection of trace amounts of water impurities in several water-miscible organic solvents. The MACDs exhibited stable dual-color fluorescence emission under ultraviolet light irradiation and red and blue emissions in organic solvents and water. The fluorescence quantum yield was approximately 11 %, which indicates an excited intraparticle proton transfer response due to an increase in the water content within a wide response range from 0 % to 100 % (v/v) in organic solvents. The intensity of the red emission signal at 670 nm gradually decreased with an increase in the water content in the organic solvent. The MACDs could detect water with an instant response time of 55 s, a high sensitivity, and low limits of detection of 0.08 %, 1.36 %, 0.03 %, 0.04 %, 0.12 %, and 0.05 % (v/v) in ethanol, acetonitrile, dimethylformamide, methanol, isopropanol, and tetrahydrofuran, respectively. Hence, biomass-derived MACDs can serve as efficient and eco-friendly water sensors in organic solvents.

Concentration Dependence Orange Light Generation Through Sm3+‐Doped Soda Lime Alumino Borate Glasses for Orange Laser Medium Material

The melt‐quenching technique is used to fabricate calcium sodium aluminum borate glasses (Sm: ANCB) doped with varying concentrations of Sm3+ ions. Characteristics of ANCBSm glasses, including density, molar volume, refractive index, absorption, emission (via visible light, X‐ray, and proton excitation), decay time, and CIE color coordinates, are analyzed. The density, molar volume, and refractive index of ANCBSm glass increased with Sm2O3 concentration. Sm3+ ions enabled photon absorption in both visible and NIR regions, with a strong reddish‐orange emission at 600 nm due to the 6H5/2 → 6P3/2 transition under various excitations. X‐ray excitation is also compared with BGO scintillation crystals. The J–O theory predicted the radiative properties of Sm3+ ion emission levels. Decay curves of the 6H5/2 levels showed a single exponential nature with a millisecond‐order lifetime. CIE chromaticity of ANCBSm glasses is in the reddish‐orange region. ANCBSm glasses have potential applications in orange laser medium material.

Theoretical investigation on regulating photophysical properties and proton transfer behavior by electronegativity for near-infrared emitting styryl dyes.

Our main focus is to explore the atomic electronegativity-dependent photoinduced behavior of styryl derivatives (HBO, HBS, and HBSe). The results of structural parameter calculation by the DFT method show that the intramolecular hydrogen bonds of normal and tautomer form are strengthened and weakened, respectively, in an excited state (S1), which is conducive to the excited intramolecular proton transfer (ESIPT) process. The enhancement of excited hydrogen bond is beneficial to the ESIPT process from the aspects of infrared vibration frequency (IR), Mulliken's charge analysis, and density gradient reduction (RDG). Additionally, by determining the bond energy with the band critical point (BCP) parameter, we found that the lower the electronegativity of the atom, the larger the hydrogen bond strength at the excited state and the more likely ESIPT reaction occurs. Meanwhile, the intramolecular H-bonds O-H…N in HBO, HBS, and HBSe are enhanced with the weakened electron-withdrawing capacity of the atom (from O to S and Se). Subsequently, frontier molecular orbital (FMOs) and charge density difference (CDD) analyses essentially revealed that electron redistribution induces the ESIPT process. Low atomic electronegativity exhibits the high chemical activity of the excited state. Furthermore, to demonstrate the electronegativity-dependent ESIPT behavior of the system, we built potential energy curves (PECs) and located the transition states (TS) of proton transfer processes.

Ortho-Vanillin-based fluorescent sensor with ESIPT characteristics for selective detection of Al(III) in aqueous solutions and its application for plant and live-cell imaging

A new acylhydrazone fluorescent sensor (VN62) with excited intramolecular proton transfer (ESIPT) characteristics has been designed and synthesized through condensation of o-vanillin with 6‑hydroxy-2-naphthoic hydrazide for selective detection of Al3+ in aqueous medium. The structure of the VN62 sensor was characterized by various techniques such as 1H and 13C NMR and mass spectrometry, and also confirmed by single crystal X-ray diffraction. The VN62 sensor showed a remarkable fluorescence enhancement response to Al3+ over a broad pH range in a nearly 100 % aqueous solution without interference by most of tested metal ions and anions. Through fluorescence titration and a Job's plot experiment, the binding stoichiometry of VN62 with Al3+ was found to be 1:1. The limit of detection of VN62 toward Al3+ was determined as 39.6 nM and the binding constant was 2.66 × 104 M−1. Comprehensive analyses by HR-MS, 1H NMR and density functional theory calculations illustrated that the VN62 sensor coordinated with Al3+, forming a stable trigonal bipyramid structure complex, which blocked the ESIPT and photoinduced electron transfer processes and simultaneously promoted an intramolecular charge transfer process, thereby leading to strong cyan fluorescence. Moreover, VN62-loaded test strips were successfully applied for rapid and visual detection of Al3+. Furthermore, the VN62 sensor was used to visualize Al3+in plants and live cells. The results indicated that the VN62 sensor has great potential for detecting Al3+in biological systems.

Selective recognition of Zn(II) by a novel Schiff base chemosensor with the formation of an AIE active Zn(II) complex having picric acid detection ability: Application in live cell imaging study

The present work highlights the development and spectroscopic identification of a Schiff base chemosensor, (Z)-4-bromo-2-(((1-methoxybutan-2-yl)imino)methyl)phenol, (HL), for selective detection Zn(II) via turn-on fluorescence among a number of competing cations in a 9:1 DMSO-water media. The high binding constant value, measured during titration of HL and Zn(II), boosts to conduct a straightforward condensation reaction between HL and Zn(II) which results in solid crystals of Zn(II) complex (complex 1). In 7:3 DMSO-water media, complex 1 display Aggregation Induced Emission (AIE) behavior, as a result of which, with increasing the water percentage, under UV light optically the cyan color complex 1 solution converts to green color with the enhancement of fluorescence intensity. The UV, fluorescence, DLS, and SEM studies, fully approve the probe's AIE active behavior. The AIE active property of complex 1 is implemented to detect picric via turn-off fluorescence. The chelation-induced enhanced fluorescence (CHEF) on and Excited state internal proton transfer (ESIPT) off are the key factors in showing the luminescence property of complex 1 and the distortion of aggregation behavior of complex 1 in the presence of picric acid leads to the turn-off fluorescence of the complex 1 solution. The mass spectral and IR spectral analysis supports the 1:1 stoichiometric addition of the probe and analyte and the structure of the probe-analyte complexes is optimized using density Functional Theory (DFT) study. Finally, the live cell imaging study enables us to independently verify the biosensing behavior of complex 1 and HL towards Zn(II) and picric acid respectively.

An alternative viewpoint on the nuclear structure towards 100Sn: Lifetime measurements in 105Sn

This work aims at presenting an alternative approach to the long standing problem of the B(E2) values in Sn isotopes in the vicinity of the N=Z double-magic nucleus 100Sn, until now predominantly measured with relativistic and intermediate-energy Coulomb excitation reactions. The direct measurement of the lifetime of low-lying excited states in odd-even Sn isotopes provides a new and precise guidance for the theoretical description of the nuclear structure in this region. Lifetime measurements have been performed in 105Sn for the first time with the coincidence Recoil Distance Doppler Shift technique. The lifetime results for the 7/21+ first excited state and the 11/21+ state, 2+(104Sn) ⊗ν1g7/2 multiplet member, are discussed in comparison with state-of-the-art shell model and mean field calculations, highlighting the crucial contribution of proton excitation across the core of 100Sn. The reduced transition probability B(E2) of the 11/21+ core-coupled state points out an enhanced staggering with respect to the B(E2; 21+→01+) in the even-mass 104Sn and 106Sn isotopes.

A proton pairing isomer in 174Hf: Reinterpretation of data and support for the split prolate–oblate pairing approximation for deformed nuclei

The available data on the even–even isotope 174Hf are reinterpreted to conclude that the low-lying 02+ level, usually regarded as a “β vibration”, is actually a proton (2p–2 h) excitation known as a Pairing Isomer. This is the first identification of a Pairing Isomer based on Proton Nilsson Orbitals. Its identification demonstrates that Pairing Isomers can exist anywhere in the Nuclear Chart if the positioning of the Fermi Surface is favourable with respect to relevant Nilsson orbitals.

A smart metasurface for scanning deep brain tissues at 1.5T MRI

Magnetic resonance imaging (MRI) is a dual phase clinical diagnostic procedure based on nuclear magnetic resonance (NMR). In the transmission phase, the body protons are stimulated by an externally applied RF field. During the reception phase, the excited protons release RF signals which are used for imaging. The signal-to-noise ratio (SNR) of scanned images can be improved by enhancing the RF magnetic flux density. However, high strength of RF magnetic fields during excitation might cause tissue heating and inhomogeneous field distribution in the subject under scan. Selective enhancement of RF magnetic flux density solely during the imaging phase is required for averting tissue heating and image artifacts while maintaining high SNR. In order to facilitate this, we report a nonlinear metasurface which could act as a dynamic supplement to transceiver MRI coils for obtaining images with higher spatial resolution or faster acquisition while maintaining low specific absorption rate (SAR).

A multifunctional fluorescent probe based on Schiff base with AIE and ESIPT characteristics for effective detections of Pb2+, Ag+ and Fe3+

In this work, three Schiff-based fluorescent probes with aggregation-induced emission (AIE) and excited intramolecular proton transfer (ESIPT) characters were synthesized by grafting 2-aminobenzothiazole group onto 4-substituted salicylaldehydes. More important, a rare tri-responsive fluorescent probe (SN-Cl) was developed by purposeful variation of substituents in the molecule. It could selectively identify Pb2+, Ag+ and Fe3+ in different solvent systems or with the help of masking agent and show complete fluorescence enhancement without interference of other ions. Meanwhile, the other two probes (SN-ON and SN-N) could only recognize Pb2+ in DMSO/Tris-HCl buffer (3: 7, v/v, pH = 7.4). According to Job’s plot, density functional theory (DFT) calculations and NMR analysis, coordination between SN-Cl and Pb2+/Ag+/Fe3+ was determined. The LOD values for three ions were as low as 0.059 μM, 0.012 μM and 8.92 μM, respectively. Ideally, SN-Cl showed satisfactory performance in real water samples detection and test paper experiments for three ions. Also, SN-Cl could be used as an excellent imaging agent for Fe3+ in HeLa cells. Therefore, SN-Cl has the ability to be a “single fluorescent probe for three targets”.

Цифровая осциллография полимерных мембран с протонной проводимостью

Polyvinyl alcohol-based cast membranes have promising application in creating commonly available fuel cells and fuel synthesizers, as well as inexpensive water sources and microelectromechanical systems. In order to control the properties of such membranes a deep understanding of the charge transfer mechanisms and their relationship with the structure formed at a certain composition and manufacturing technology is required. A method for studying the structure of the proton-conductive polymer membranes using digital oscillography of ion currents excited by the low-frequency rectangular pulses with the amplitudes below the threshold voltage of the ionic conductivity in a dehydrated membrane, and for the analysis of the resulting ion current pulses (spikes) in the frames of the model of a proton pump acting in each layer of the membrane is proposed in this paper. Fast Fourier transform of these oscillograms reveals from 2 to 4 branches or spike sequences corresponding to the phases with different ionic conductivity and makes it possible to determine the thicknesses of both high-conductivity phase layers (7–30 µm) and low-conductivity phase interlayers (1–7 µm) formed in the process of polymerization. The reason of spike merging into bursts is described in terms of successively induced increase in the excited proton density over a threshold value in highly conductive layers. The resonance observed in dry proton membranes at the frequencies of about 2.2 to 3.0 kHz is interpreted as the burst merge point with the further increase in impedance due to proton lagging and respective decrease in the effective thickness of active layers. The effective charge carrier concentrations (as small as 1012 to 1013 cm−3) and the velocity (from 5 to 18 cm/s for the highly conductive phases which turned out to be much higher than those observed in solutions) are estimated. The asymmetry of the cast membranes, which becomes apparent at low frequencies and causes the generation of a direct ion current in response to excitation by a purely alternating current, is studied. It is found that the apparent conductivity determining contribution to the total ohmic resistance is made by a thin interlayer with a very low ion velocity, presumably surface layer, rather than the main layers. The conclusion on the optimization of the production technology and the composition of the proton membranes for various applications is made.

Caught in the act: real-time observation of the solvent response that promotes excited-state proton transfer in pyranine.

Photo-induced excited-state proton transfer (ESPT) reactions are of central importance in many biological and chemical processes. Identifying mechanistic details of the solvent reorganizations that facilitate proton transfer however, is challenging for current experimental and theoretical approaches. Using optical pump THz probe (OPTP) spectroscopy and molecular dynamics simulations, we were able to elucidate the ultrafast changes in the solvation environment for three derivatives of pyranine: the photoacid HPTS, the methoxy derivative MPTS, and the photobase OPTS. Experimentally, we find damped oscillations in the THz signal at short times and our simulations enable their assignment to vibrational energy transfer beatings between the photoexcited chromophore and nearby solvent molecules. The simulations of HPTS reveal strikingly efficient sub-ps energy transfer into a particular solvent mode, that is active near 4 THz, and which can provide the requisite energy required for solvent reorganization promoting proton transfer. Similar oscillations are present in the THz signal for all three derivatives, however the signal is damped rapidly for HPTS (within 0.4 ps) and more slowly for MPTS (within 1.4 ps) and OPTS (within 2.0 ps). For HPTS, we also characterize an additional phonon-like propagation of the proton into the bulk with a 140 ps period and an 83 ps damping time. Thermalization of the solvent occurs on a time scale exceeding 120 ps.

Multielectron ionization contributions in valence‐to‐core x‐ray emission spectra of third‐row elements

AbstractThe valence‐to‐core (VtC) K x‐ray emission spectroscopy (XES) in the tender x‐ray range is emerging as a powerful analytical technique used to study the electronic structure of third‐row elements within complex bulk materials. With dedicated tender x‐ray emission spectrometer coupled with laboratory excitation source, such analysis can be successfully performed also in a smaller lab. In this work, we have gathered VtC x‐ray emission spectra of several sulfur and chlorine compounds measured previously in our home lab using Johansson type tender x‐ray emission spectrometer and MeV proton excitation. Measured spectra are compared to the results of one‐electron density functional theory (DFT) calculations. Theoretical spectra were found in good agreement with the experimental data with few exceptions where systematic discrepancies were observed. The latter was attributed to the simultaneous K and M shell ionization induced by MeV protons, which is not included in the one‐electron DFT theoretical framework. In order to confirm this also experimentally, VtC x‐ray emission spectra of few selected S and Cl compounds induced with three different proton energies were recorded yielding characteristic KM ionization satellite lines, confirmed by their emission energies as well as the dependence of their relative intensity on proton energy.

Enhanced proton pseudocapacitive of Ti3C2Tx in neutral electrolyte activated by acid regulation dynamic pillars

Aqueous Zinc ion capacitors (ZICs) using 2D transition metal carbides or nitrides (MXenes) have extraordinary energy density and wide potential range. However, low pseudocapacitance and slowly divalent charges (e.g., zinc ions) transfer in MXene nano sheets are the essential issues in exploring MXene-based ZICs of greater energy densities. Herein, the strategy of using Al3+ as dynamic acid regulation pillars is demonstrated to address these issues. Attributing to dynamically expanded layer spacing, adjustable acid of electrolyte and excited proton pseudocapacitance, enhanced capacity values of 277.9 F g-1 with a high voltage range from -1 to 0.3 V is achieved. The energy density of asymmetric ZICs constructed applied this strategy exhibits superior energy densities of 37.7 Wh kg-1 with outstanding cycling stability, which has been greatly improved compared with traditional acidic and neutral electrolytes. DFT calculations reveal the enhancement mechanism of acid regulation dynamic pillars on electrochemical performance. Our study provides a pathway for precise control of Ion selectivity in MXene energy storage process, and could be further used for other electrolyte systems and aqueous Zn-ion electrodes as well.

A benzothiazole-based “on-off” fluorescence probe for the specific detection of Cu2+ and its application in solution and living cells

In this paper, a novel fluorescent probe HBT-H based on benzothiazole has been designed and synthesized. The probe has excellent selectivity and can be used for specific detection of Cu2+. Under 360 nm UV excitation, the probe HBT-H itself has a fluorescence emission peak at 487 nm, emitting cyan blue fluorescence, fluorescence quenching after added Cu2+. The detection limit of Cu2+ recognition by HBT-H probe was calculated as 3.08 × 10−7 M. According to Job's plot and high resolution mass spectrometry, the complexation ratio of HBT-H to Cu2+ was 2:1. The sensor mechanism was confirmed as excited intramolecular proton transfer (ESIPT). Surprisingly, the probe HBT-H system responded well to pH, showing green fluorescence under acidic conditions and cyan blue fluorescence under alkaline conditions. In addition, the probe HBT-H has excellent membrane permeability and low cytotoxicity, which could not only detect Cu2+ in actual water samples, but also recognize Cu2+ in human breast cancer cells (MCF-7).

A flavonol-derived fluorescent probe for highly specific and sensitive detection of hydrazine in actual environmental samples and living zebrafish

Hydrazine (N2H4) is a significant chemical reagent and widely applied in industrial field, which can bring potential risk to environmental safety and human health due to its high toxicity and potential carcinogenicity. In this paper, a flavonol-derived fluorescent probe named TB-N2H4 was rationally developed for detecting N2H4 based on the excited intramolecular proton transfer (ESIPT) principle. TB-N2H4 exhibited a remarkable fluorescence turn-on response toward N2H4 with a large Stokes shift of 191 nm. Moreover, TB-N2H4 could selectively recognize N2H4 over other competitive analytes, and displayed high sensitivity toward N2H4 with a low detection limit of 0.117 μM. The sensing mechanism of the probe TB-N2H4 for N2H4 was confirmed by theoretical calculation and HRMS analysis. This probe was able to quantitatively determine N2H4 in environmental water and soil samples. Additionally, TB-N2H4 was also successfully utilized for real-time tracking of the distribution of N2H4 in living zebrafish.

Multistep Coulomb excitation of Ni64 : Shape coexistence and nature of low-spin excitations

The structure of $^{64}\mathrm{Ni}$, the heaviest stable Ni isotope, has been investigated via high-statistics, multistep safe Coulomb excitation to search for shape coexistence, a phenomenon recently observed in neutron-rich $^{66}\mathrm{Ni}$ and $^{70}\mathrm{Ni}$ as well as in doubly magic, $N=40, ^{68}\mathrm{Ni}$. The study was motivated by recent, state-of-the-art Monte Carlo shell-model calculations (MCSM), where a Hamiltonian with effective interactions incorporating the monopole tensor force predicts the existence of shape coexistence, also in the lower-mass $^{62,64}\mathrm{Ni}$ isotopes. A set of transition and static $E2$ matrix elements for both yrast and near-yrast structures was extracted from the differential Coulomb excitation cross sections. From comparisons between the new results and MCSM as well as other shell-model calculations, a clearer picture of the structure of $^{64}\mathrm{Ni}$ emerges. Specifically, the low-spin states are shown to be dominated by proton and neutron excitations mainly within the $fp$ shell, with minimal contribution from the ${g}_{9/2}$ shape-driving neutron orbital. The agreement between experimental data and MCSM results indicates a small oblate deformation for the ${0}_{2}^{+}$ level and a spherical shape for the ${0}_{3}^{+}$ state. In addition, the small upper limit determined for the $B(E2)$ probability of a transition associated with the decay of the recently observed 3463-keV, ${0}_{4}^{+}$ state agrees with its proposed assignment to a prolate shape, herewith providing first evidence for triple shape coexistence in a stable Ni isotope.

Reinvestigation of the level structures of the N=49 isotones Zr89 and Mo91

Excited states of $^{89}\mathrm{Zr}$ and $^{91}\mathrm{Mo}$ have been investigated using the fusion reaction $^{6}\mathrm{Li}+^{89}\mathrm{Y}$ at beam energy of 34 MeV. Based on new experimental data, about 16 (13) new transitions have been added to the level scheme of $^{89}\mathrm{Zr}$ ($^{91}\mathrm{Mo}$). The level structures are investigated in the framework of the spherical-basis shell model using the effective interactions JUN45 and GWBXG. Reasonable agreement is obtained between the experimental results and the calculations. The calculated results indicate the newly proposed states are characterized by proton excitations from the $1{f}_{5/2}, 2{p}_{3/2}, 2{p}_{1/2}$ orbits to the high-$j 1{g}_{9/2}$ orbit. The systematic features of low lying states in the $N=49$ isotones are discussed.

Triple electron-electron-proton excitations and second-order approximations in nuclear-electronic orbital coupled cluster methods.

The accurate description of nuclear quantum effects, such as zero-point energy, is important for modeling a wide range of chemical and biological processes. Within the nuclear-electronic orbital (NEO) approach, such effects are incorporated in a computationally efficient way by treating electrons and select nuclei, typically protons, quantum mechanically with molecular orbital techniques. Herein, we implement and test a NEO coupled cluster method that explicitly includes the triple electron-electron-proton excitations, where two electrons and one proton are excited simultaneously, using automatic differentiation Our calculations show that this NEO-CCSDTeep method provides highly accurate proton densities and proton affinities, outperforming any previously studied NEO method. These examples highlight the importance of the triple electron-electron-proton excitations for an accurate description of nuclear quantum effects. Additionally, we also implement and test the second-order approximate coupled cluster with singles and doubles (NEO-CC2) method as well as its scaled-opposite-spin (SOS) versions. The NEO-SOS'-CC2 method, which scales the electron-proton correlation energy as well as the opposite-spin and same-spin components of the electron-electron correlation energy, achieves nearly the same accuracy as the NEO-CCSDTeep method for the properties studied. Because of its low computational cost, this method will enable a wide range of chemical and photochemical applications for large molecular systems. This work sets the stage for a variety of developments and applications within the NEO framework.