Intensity Of Spectra Research Articles

Localized and Excimer Triplet Electronic States of Naphthalene Dimers: A Computational Study

We perform DFT calculations with different hybrid (ωB97X-D and M05-2X) and double hybrid (B2PLYP-D3 and ωB2PLYP) functionals to characterize the lowest energy triplet excited states of naphthalene monomer and dimers in different stacking arrangements and to simulate their absorption spectra. We show that both excimer and localized triplet minima exist. In the former, the spin density is delocalized over the two monomers, adopting a face-to-face arrangement with a short inter-molecular distance. In the latter, the spin density is localized on a single naphthalene molecule, and different minima or pseudo-minima are possible, the most stable one corresponding to a slipped parallel arrangement. According to B2PLYP-D3 calculations, excimer minima are the most stable, in line with the indications of ADC(2) studies. However, the relative stability of the minima is reverted when including thermal and vibrational effects. Excimer minima exhibit a very intense absorption spectrum, peaking above 500 nm. The computed absorption spectra of localized minima significantly depend on the stacking geometry and do not coincide with that of isolated naphthalene. Hybrid functionals provide very accurate vibronic absorption spectra for naphthalene monomer, both in the singlet and in the triplet state, but underestimate the stability of the excimer triplet.

Coupling of single nanodiamonds hosting SiV color centers to plasmonic double bowtie microantennas.

Color centers are promising single-photon emitters owing to their operation at room temperature and high photostability. In particular, using nanodiamonds as a host material is of interest for sensing and metrology. Furthermore, being a solid-state system allows for incorporation to photonic systems to tune both the emission intensity and photoluminescence spectrum and therefore adapt the individual color center to desired properties. We show successful coupling of a single nanodiamond hosting silicon-vacancy color centers to a plasmonic double bowtie antenna structure. To predict the spectrum of the coupled system, the photoluminescence spectrum of the SiV centers was measured before the coupling process and convoluted with the antenna resonance spectrum. After transferring the nanodiamond to the antenna the combined spectrum was measured again. The measurement agrees well with the calculated prediction of the coupled system and therefore confirms successful coupling.

Vocal Instabilities in Untrained Female Singers.

This study aimed to identify voice instabilities across registration shifts produced by untrained female singers and describe them relative to changes in fundamental frequency, airflow, intensity, inferred adduction, and acoustic spectra. Multisignal descriptive study. Five untrained female singers sang up to 30 repetitions of octave scales. They first produced these octave scales "naturally," followed by productions that were either deliberately smooth or deliberately unsteady. With all types of scaleproductions, participants sang with both /α/ and /i/ vowels, at two different dynamic levels, and across both the upper and lower predetermined register transitions. Recorded scales were categorized into three groups (Smooth, Middle, Unsteady) based on researcher-based perceptual smoothness of the auditory signals. These groups allowed for determination of salient features of unsteadiness based on observations and analyses of the acoustic, airflow, intensity, and electroglottography (EGG) waveforms. A total of 13 different types of instabilities were observed. The number of instabilities within a single scale ranged from zero to fourteen. Most Smooth scales had zero to three instabilities, most Middle scales had four to six, and most Unsteady scales had six or more instabilities within the scale. More obvious instabilities, such as aphonic segments, were present only in Unsteady scales, while more subtle instabilities, such as those related to EGG signal changes, were common in all scale categories, including Smooth scales. This study revealed that untrained singers can sing smoothly throughout octave scales, and the primary unsteadiness variable was an aphonic segment and corresponding abrupt and large intensity reduction. Particular instabilities may be related to subtle aspects of register change and vocal control. Some objective measures appear to be more visually and numerically salient than auditorily perceived events relative to unsteadiness in the production of scales.

Spectroscopic study of energy transfer in collisions between vibrational excited H2 and CO2.

The collisional energy transfer between vibrational excited H2(1, 7) and CO2 was investigated by exciting H2 to a vibrational excited state of v = 1, J = 7 by the stimulated Raman scattering technique. The coherent anti-Stokes Raman spectroscopy (CARS) technique determined that H2 was excited to the H2(1, 7) state. Varying the cuvette temperature, the number of H2(1, 7) particles was found to increase with the increase in H2 molar ratio α by scanning the intensity of the CARS spectrum, with peaks at different α at a temperature of 363 ± 15K, but the peak temperature was not sensitive to α. Scanning CARS spectra after H2 collisions yielded that the energies of the excited states of H2 were mainly distributed in the vibrational and translational states, proving that the collisions between the excited states of H2 were linear collisions. The collisional transfer rate coefficients of H2(1, 7) and CO2 were obtained by fitting the Stern-Volmer equation as kv(H2) = (2.89 ± 0.30) × 10-13cm3s-1 and kv(CO2) = (8.23 ± 0.42) × 10-13cm3s-1. Exciting H2 to different states, it was found that the collisional transfer rate coefficient of CO2 was less affected by the energy of the vibrational excited H2. The rotational temperature was obtained from the Boltzmann distribution of the rotational dynamics, and it was found that the rotational temperature of CO2(0000, J) was about 3.4 times higher than that of CO2(0001, J), which proved that the energy of the vibrational excited H2 was mainly allocated to the higher rotational state of CO2(0000).

Correlations between spectrum-based and other ground-motion intensity measures considering various damping ratios

Spectral acceleration at a given period, SA( T), is usually combined with other intensity measures (IMs) for vector-valued ground-motion selection and seismic hazard assessment. The correlations between SA( T) and other IMs have been extensively studied, based on the SA-related IM pairs with a damping ratio ( ξ) of 5%. Yet, ξ varies notably with various types of structures. This article thus investigates the correlations of SA( T, ξ) with 10 commonly used non-SA IMs (e.g. Arias intensity), and the correlations of damping-specific acceleration spectrum, spectrum, and displacement spectrum intensities, namely ASI( ξ), SI( ξ), and DSI( ξ), with the other IMs. Comprehensive correlation analyses are conducted to derive the correlations for the IM pairs considered based on the NGA-West2 database and compatible ground-motion models. The results indicate that increasing ξ generally yields stronger correlations, and the difference between the ξ-specific and 5%-damped correlation coefficients could be larger than 0.2. The neural network and polynomial regressions are subsequently used to develop parametric models for estimating the correlations of SA( T, ξ)-containing pairs and the other IM pairs, respectively. All the models developed exhibit good performance in terms of predictive accuracy. The application of the proposed models is demonstrated within the generalized conditional IM approach. The models proposed could be useful for ground-motion selection and seismic demand or risk assessment for structures with various ξ values.

Photophysics of Hydrophobic Corroles in the Aqueous Micellar Media and in the Presence of Graphene Oxide and Bioanalytes.

Here two A2B type corrole has been synthesized and solubilized in water via pluronic micellar system by avoiding the utmost mandatory multistep non-environment friendly strategies for bringing hydrophobic non-ionic corroles in aqueous medium. Both the corroles were extremely insoluble in water as no absorption spectra of corrole was available in water. However, corrole 2 in the aqueous solution of F127 exhibit characteristic Soret and Q bands due to efficient solubilization of corrole in F127, the micelles formed by block copolymer act as a "cargo hold" for the corrole molecules. Intense emission spectra were observed for both the corroles in the aqueous solution of F127. We further observed that fluorescence properties of corrole-F127 micelle systems are quenched in presence of graphene oxide (GO) without change in the wavelength or shape of the emission band. The possibility of a dynamic quenching is probed more quantitatively by recording the emission decay profiles of corrole-F127-GO system. This quenching of fluorescence intensity of graphene oxide dispersed corrole-F127 micellar system was partially re-established in the presence of bioanalytes such as dopamine, ascorbic acid. Therefore, the present work has a future potential application for analyzing the interaction with different bioanalytes in biological systems using corrole-GO composite.

Evaluation of Breast Cancer Gene Type 1 (BRCA1) Protein Levels in Cancer Tissue Using Surface-Enhanced Raman Spectroscopy.

Raman spectroscopy is a chemical process that utilizes the interaction between light and matter to get significant insights into the structure or characteristics of matter. Raman spectroscopy techniques, such as quantitative evaluation, early diagnostic capabilities, and elucidation of the spectral properties of tissues, are excellent candidates for use in research. In cancer, changes in genes and proteins expressed by related genes are associated with a poor prognosis and aggressive tumor characteristics. Due to modifications and regulatory steps in protein translation, the results of the messenger RNA (mRNA) expression of genes may not correctly reflect the results of protein expression. For this reason, the mRNA and protein expressions of genes are studied in parallel in molecular studies on cancer. In our study, the breast cancer gene type 1 (BRCA1) gene, which is frequently studied in breast cancer and is relatively more difficult to measure by traditional methods due to its high molecular weight, was selected, and protein quantification was performed in tissue samples by Raman spectroscopy. With Raman spectroscopy, it is possible to obtain rapid and precise quantitative results even with a small amount of sample, so it is quite advantageous compared to traditional methods. In our study, we performed surface-enhanced Raman spectroscopy (SERS) to analyze the quantitative protein amount. SERS is a highly sensitive method for detecting compounds at low concentrations. For this purpose, magnetic nanoparticles modified with protein antibodies were used, and the target protein was withdrawn from the complex environment and transferred to an appropriate buffer environment. The calibration curve for BRCA1, which plots Raman intensity against concentration, was derived by calculating the average response reading from duplicate assays conducted under identical conditions. The BRCA1 protein levels of cells were determined from the regression curve of the BRCA1 protein. The relation between the concentration of BRCA1 protein and SERS spectrum intensity was determined to be logarithmic in the range of 300 µg·mL-1 to 292 ng·mL-1 (R2 = 0.9928, limit of detection = 10.41 µg·mL-1, and limit of quantitation = 31.24 µg·mL-1).

Correlation between spin-dependent recombination centers and long-lived polarons generated in organic photovoltaic devices revealed by successive ESR and EDMR measurements

Using a successive detection technique with electron spin resonance (ESR) and electrically detected magnetic resonance (EDMR), this study clarifies the quantitative correlation between photoinduced spin amounts and spin-dependent recombination (SDR) currents in organic photovoltaic devices (OPVs). Using this unique method of sequentially switching between ESR and EDMR measurements under light irradiation, we find that the intensities of light-induced ESR and EDMR spectra increase along with the light irradiation power. Although positive correlation exists between the number of photo-generated radicals and the SDR currents, the relation is not proportional, which demonstrates that most of the photo-generated radicals are residual accumulated charges. Additionally, phases of the EDMR spectra under light irradiation were found to be changed because of a delay of modulated EDMR signals. The phase variation is probably caused by recombination centers: positive polarons that have arrived at the interface between an aluminum electrode and an active layer by charge drifting after charge separation. Because positive polarons are expected to transport positive charges to the opposite-side electrode of the aluminum as a negative charge collector, this leakage current can be a factor of disturbing an optimal charge collection. This combined technique of ESR and EDMR is useful to explore the different roles of polarons in the photovoltaic conversion processes, thereby providing important information for improving the fill factors and open-circuit voltages of the OPVs, which generate long-lived polarons.

Interactions of hydrophobically associating polymers with anionic surfactant sodium dodecylbenzene sulfonate: Experiments and simulations

Herein, the interaction of the hydrophobically associating polymer HP-1 with the anionic surfactant sodium dodecylbenzene sulfonate (SDS) was investigated using solution viscosity by Brookfield viscometer, rheology including steady shear rheology and dynamic frequency sweep rheology, ambient scanning electron microscopy, and fluorescence measurements and then simulated and analyzed using dissipative particle dynamics simulations (DPD). The results showed that as SDS concentration increased, the solution viscosity of the HP-1/SDS system first declined, then increased, reached a peak, and then decreased again before gradually leveling off. The rheology and microscopic morphology of the system exhibited similar patterns of change. The system’s solution shear rheology and viscoelasticity decreased with increasing SDS concentration, then increased and ultimately decreased, and the system’s reticulation structure changed from loose to tight and then again to loose, according to the law of composite viscosity. Moreover, the ratio of the emission peak intensities of the monomer fluorescence spectra of pyrene molecules in solution at 372 and 383 nm (I3/I1) first decreased, then increased, and finally stabilized. This implies that the above phenomenon is associated with the change in the number of HP-1’s hydrophobic interaction. Thus, SDS affects both the binding efficiency and number of binding groups of HP-1, resulting in a change in the properties of the solution. Finally, DPD simulations were performed to study the interaction between SDS and HP-1, confirming the experimental data-derived supposition. Upon the addition of SDS, it began to interact with HP-1 hydrophobic groups until all of the hydrophobic groups were coated with SDS, resulting in coiling of the HP-1 polymer chains. Meanwhile, SDS molecules adsorbed onto the polymer chain and aggregated with each other to form micelles, altering the properties of the solution.

SCExAO/CHARIS Near-infrared Scattered-light Imaging and Integral Field Spectropolarimetry of the AB Aurigae Protoplanetary System

We analyze near-infrared integral field spectropolarimetry of the AB Aurigae protoplanetary disk and protoplanet (AB Aur b), obtained with SCExAO/CHARIS in 22 wavelength channels covering the J, H, and K passbands (λ 0 = 1.1–2.4 μm) over angular separations of ρ ≈ 0.″13 to 1.″1 (∼20–175 au). Our images resolve spiral structures in the disk in each CHARIS channel. At the longest wavelengths, the data may reveal an extension of the western spiral seen in previous polarimetric data at ρ < 0.″3 out to larger distances clockwise from the protoplanet AB Aur b, coincident with the Atacama Large Millimeter/submillimeter Array–detected CO gas spiral. While AB Aur b is detectable in complementary total intensity data, it is a nondetection in polarized light at λ > 1.3 μm. While the observed disk color is extremely red across JHK, the disk has a blue intrinsic scattering color consistent with small dust grains. The disk’s polarization spectrum is redder than AB Aur b’s total intensity spectrum. The polarization fraction peaks at ∼0.6 along the major disk axis. Radiative transfer modeling of the CHARIS data shows that small, porous dust grains with a porosity of p = 0.6–0.8 better reproduce the scattered-light appearance of the disk than more compact spheres (p = 0.3), especially the polarization fraction. This work demonstrates the utility of integral field spectropolarimetry to characterize structures in protoplanetary disks and elucidate the properties of the disks’ dust.

Побудова моделі базової лінії диференціальних сигналів вимірювання

Introduction. Environmental pollution has a significant impact on people’s lives. Drinking water pollution with heavy metals is especially noticeable for humans. To solve this problem, it is necessary to ensure continuous monitoring of water quality, which will allow determining the concentration of toxic elements in it. It is necessary to isolate the useful component of the signal containing information on unknown concentrations of the measured elements, against the background of a mixture of various signals of elements present in the background solution. For this purpose, a method for constructing a basic model is proposed, according to which it is possible to separate the differential signal of the inversion of chemical elements in water from the background signal of impurities present in water. Due to this, a spectrum of a multicomponent intensity signal is formed in pure form, the analysis of which allows one to accurately estimate the unknown concentrations of a mixture of these dissolved elements. Purpose. To develop a method for constructing an approximation function for the lower envelope of the background intensity signal in different classes of basic functions using GMDH in the problem of determining the concentrations of chemical elements in multicomponent signals when measuring the ecological state of environmental objects using electrochemical methods of inversion chronopotentiometry. Methods. The methods that are used in this article are of inversion chronopotentiometry method and GMDH neural network. Results. The problem of constructing a baseline for the multicomponent signal of the intensity of inverse chronopotentiometry, the determination of which allows to estimate the concentration of various chemical elements dissolved in water quite accurately, is investigated. To solve this problem, an approach to construction of the approximation function of the lower envelope line of the differential signal in different classes of basic functions with the use of GMDH is proposed. The approach was used for constructing the best model of the differential signal baseline on the real example of measuring the Zn concentration under the presence of ions Cd, Pb, Cu. The built model of optimal complexity is the sum of arguments with the direct and inverse degrees which is necessary for clearing the intensity signal from background to obtain the intensity spectrum of the measured chemical elements. Conclusion. Produced in the C2 class, it can be recommended for use in the task of providing the baseline of a differential signal, since it can practically be the same R2, but also the richly shortening MAPE.

Spin-Selective Charge Transfer-SERS Driven Label-Free Enantioselective Discrimination of Chiral Molecules on Ag Nanoparticle-Decorated Ni Nanorod Arrays.

Enantioselective discrimination is critical in several fields, particularly in pharmaceutics and clinical drug research. Chiral molecules possess unique charge transfer properties, showing an enantioselective preference for electron spin orientation when interacting with the magnetic surface. Here, we developed spin-selective charge transfer (SSCT)-based label-free surface-enhanced Raman scattering (SERS) achiral magnetic substrates for the enantioselective discrimination of chiral molecules without creating asymmetric chiral adsorption sites. The e-beam-based glancing angle deposition (GLAD) technique was utilized to construct achiral magnetic surface-enhanced Raman scattering (SERS) substrates by decorating Ag nanoparticles over Ni nanorods. SERS spectroscopy was carried out on significant enantiomers, including cystine, alanine, and DOPA (l-3-(3,4-dihydroxyphenyl) alanine). An external electromagnet was used to manipulate the magnetic substrate's spin polarization by altering the magnetic field's direction. Subsequently, SERS spectra were acquired. Based on the magnetic field's direction, there is a complementary variation in the intensities of SERS spectra of the enantiomers. The SSCT process between molecule-metal complexes synergized with the magnetic field direction to control the electron spin, leading to SERS-based enantioselective discrimination. This label-free, easy, yet practical approach offers a characteristic paradigm shift from the recent complex approaches for chiral detection and separation.

Kinematical and Physiological Responses of Overground Running Gait Pattern at Different Intensities.

Runners achieve forward locomotion through diverse techniques. However, understanding the behavior of the involved kinematical variables remains incomplete, particularly when running overground and along an intensity spectrum. We aimed to characterize the biomechanical and physiological adaptations while running at low, moderate, heavy and severe intensities. Ten middle- and long-distance runners completed an incremental intermittent protocol of 800 m steps until exhaustion (1 km·h-1 velocity increments and 30 s intervals) on an outdoor track field. Biomechanical data were captured using two high-resolution video cameras, and linear and angular kinematic variables were analyzed. With the intensity rise, a decrease in stride, step and contact times ([0.70-0.65], [0.35-0.33] and [0.42-0.37] s) and an increase in stride length and frequency and flight time ([3.13-3.52] m, [1.43-1.52] Hz and [0.28-0.29] s; p < 0.05) were observed, together with an increase in oxygen uptake and blood lactate concentrations ([54.7-67.6] mL∙kg-1∙min-1 and [3.1-10.2] mmol∙L-1). A more flexed hip at initial contact and toe-off (152.02-149.36] and [165.70-163.64]) and knee at initial contact ([162.64-159.57]; p < 0.05) were also observed. A consistent gait pattern along each protocol step was exhibited, with minor changes without practical significance. Runners are constantly adapting their gait pattern, reflected in both biomechanical and physiological responses, both of which should be considered for better characterization.

Design and synthesis of star-shaped non-fullerene acceptors based on triarylamine core for organic photovoltaic applications

Abstract Non-fullerene acceptors were synthesized with triphenylamine (TPA) and 9-phenylcarbazole core functionalized with oxindole moiety, as well as electron accepting groups such as cyano and trifluoromethyl groups, leading to precisely tuned molecular electronic structures and intermolecular arrangements. This approach maintained high thermal stability and excellent electron mobility while optimizing optoelectronic properties, providing a novel strategy for developing organic photovoltaic materials. LUMO levels of three receptors were comparable to PC61BM. The decomposition temperatures of all three acceptors exceeded 380 °C under N2 flow, indicating the exceptional thermal stability. Notably, the acceptor consisting of TPA core with three oxindole moieties exhibited the red-shifted and intense UV-vis absorption spectrum and the narrowest optical bandgap (Egopt = 2.14 eV). Furthermore, the higher electron mobility was observed in this compound compared to analogues with 9-phenylcarbozle unit. The power conversion efficiency of the device based on TPA core acceptor and regio-regular poly(3-hexylthiophene) surpassed those of the devices based on the other two acceptors.

Enzyme-assisted upconversion fluorescence-encoded biosensing system for simultaneous detection of multiple sites EGFR mutation.

Epidermal growth factor receptor (EGFR) mutations play a key role in the development of a variety of cancers. Rapid detection and screening of EGFR mutation types in patients are of great significance for early treatment of patients. In this study, a highly sensitive fluorescent biosensing system based on lanthanide ion-doped multi-type upconversion nanoparticles (UCNPs) combined with polymerization reaction signal amplification was designed and constructed for the simultaneous detection of L858R and 19Del mutations. Two upconversion nanoparticles (NaYF4:Yb, Er and NaYF4:Yb, Tm) with unique upconversion fluorescence profiles were first prepared using Er and Tm as activators, respectively. Subsequently, the UCNPs were enriched by cDNA complementary hybridization and atom transfer radical polymerization (ATRP) reactions to enhance the signal. Next, the tDNA/cDNA hybrids were cleaved using specific restriction endonucleases to detach UCNPs aggregates from the surface of the magnetic beads. Finally, the fluorescence signal in the supernatant was detected after magnetic separation. The simultaneous quantitative detection of the two EGFR mutations was achieved by analyzing the changes in signal intensity of the characteristic upconversion fluorescence spectra of the two encoded UCNPs at their respective emission peaks. The detection range of the method was from 10 fM to 10nM, and the detection limits were 2.44 fM for L858R and 2.13 fM for 19Del. The sensing system was able to effectively differentiate between wild-type and other mutation types, and its detection results were consistent with qPCR. The excellent performance of the sensor suggests its promising application in the diagnosis and precision treatment of NSCLC.

NMR Insights into Designing Safe and Efficient Lithium-Ion-Batteries with Solid Electrolyte

The inherent risk of explosion in widely used lithium-ion-batteries has ignited greater interest in the development of more efficient and safer energy storage. Notably, there is growing attention on all-solid-state batteries for their ability of providing both safe and efficient energy storage. Among the promising candidates, we focused on argyrodite-type electrolytes exhibiting high ionic conductivity on the order of some mS/cm at room temperature.In this study, we compared dual-substituted argyrodite-type electrolytes to observe the effect of the anion substitution on the physical properties of the solid electrolytes using solid state NMR. We investigated the correlation between anion substitution and the local dynamics of lithium ions through NMR relaxometry. We measured 7Li spin-lattice relaxation times (T1) in various temperature, fitted the T1 values into the Arrhenius equation and calculated the activation energy. Furthermore, by comparing the peak intensity of NMR 1D spectra before and after cycling, we confirmed the movement of Li ions between cathode and electrolyte.In short, our findings, obtained via solid-state NMR, deepen our insights on electrolytes down to the atomic level. This work gained ground for future research to develop the efficient and safe energy storage systems and drive innovation in all-solid-state batteries.

Light Therapy for Older People with Depressive Symptoms: Systematic Review and Meta-Analysis.

Background/Objectives: Light therapy has emerged as a promising non-pharmacological treatment for depressive symptoms. This meta-analysis aims to evaluate the effectiveness of light therapy specifically for depressive symptoms in elderly populations, with a focus on how different light intensities and spectra influence treatment outcomes. Methods: A systematic search targeting studies on light therapy for depressive symptoms in older adults was performed across multiple databases, including PubMed, Google Scholar, PsycINFO, and EMBASE, covering studies from database inception until July 2024. A total of 565 records were identified, with 461 studies remaining after removing duplicates. Following the screening of titles and abstracts, 54 studies underwent full-text review, resulting in the inclusion of 22 studies with a total of 1290 participants (687 in the intervention group and 603 in the control group). Results: The overall effect size for light therapy on depressive symptoms was moderate (Hedges' g = 0.525, p < 0.001). Higher light intensities (10,000 lux and above) demonstrated significantly greater effectiveness compared to lower intensities. White light had the most substantial effect, while bluish light showed moderate efficacy. Significant heterogeneity was observed across studies (I2 = 80.459%), indicating variability in treatment outcomes based on study design, intensity, and light spectrum. Conclusions: This meta-analysis confirms that light therapy is an effective treatment for reducing depressive symptoms in older adults, particularly at higher intensities and with specific light spectra such as white light. Given the heterogeneity in results, future research should focus on optimizing treatment parameters to enhance clinical outcomes within this population.

Probing the Electronic Manifold of MgCl with Millimeter-Wave Spectroscopy and Theory: (3)2Σ+ and (4)2Σ+ States.

The millimeter/submillimeter spectrum of magnesium chloride (MgCl) has been observed in two new electronic excited states, (3)2Σ+ and (4)2Σ+, using direct absorption methods. The molecule was synthesized in a mixture of Cl2, argon, and magnesium vapor. For the (3)2Σ+ state, multiple rotational transitions were measured in the v = 0 level for all six isotopologues (24Mg35Cl, 24Mg37Cl, 25Mg35Cl, 25Mg37Cl, 26Mg35Cl, and 26Mg37Cl), as well as up to v = 13 for 24Mg35Cl. For the (4)2Σ+ state, less intense spectra were recorded for 24Mg35Cl (v = 0-2). Equilibrium rotational parameters were determined for both states for 24Mg35Cl, as well as rotational constants and 25Mg hyperfine parameters for the other isotopologues. A perturbation was observed between rotational levels of the two states due to an avoided crossing. Computations were also carried out at the CASPT2 and MRCISD+Q levels, and the resulting bond lengths for (3)2Σ+ and (4)2Σ+ states agree well with the experimental values of re = 2.536 and 2.361 Å. The computations show that the (3)2Σ+ state has a double-well potential; however, the state behaves as a single well with unperturbed vibrational levels up to v = 13 due to nonadiabatic interactions with the (4)2Σ+ state.

Impact of chlorine substitution on valence orbitals and ionization dynamics in 3-chloropyridine: Insights from high-resolution vacuum ultraviolet mass-analyzed threshold ionization study.

In this study, the effects of chlorine substitution on the valence orbitals and electronic states of 3-chloropyridine (3-CP) were investigated utilizing high-resolution vacuum ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopy and computational methods. High-quality vibrational spectra were obtained from the VUV-MATI spectra of 3-CP isotopomers (35Cl and 37Cl), revealing high-quality vibrational spectra for the lowest cationic states. The adiabatic ionization energies (AIEs) of these isotopomers were accurately determined, providing detailed information about the electronic structure and ionization dynamics. Intense spectra peaks were linked with the D1 excited state of the 3-CP cation, with vibronic transitions in this state closely matching those predicted by Franck-Condon simulations. This provided insights into the cationic structure and the roles of the highest occupied molecular orbital (HOMO) and the HOMO-1. The HOMO was primarily a π orbital of the pyridine ring, while the HOMO-1 consisted of nonbonding orbitals. The AIEs suggested that meta-chlorine substitution stabilizes nonbonding orbitals less effectively than ortho substitution, indicating closely spaced electronic states in the 3-CP cation. Minor discrepancies in vibrational frequencies and intensities, particularly above 800cm-1, suggested the presence of vibronic coupling, warranting further investigation. Overall, this study provided a comprehensive understanding of the vibronic and ionization properties of 3-CP, emphasizing the influence of the position of the chlorine substitution on molecular orbitals and the value of advanced theoretical and experimental approaches for analyzing the vibrational spectra of complex molecules.

Assessing Vertical Bioturbation Intensity from Bedding Planes

Bedding planes hold significant value in ichnological analyses as they improve the recognition of ichnotaxa and yield important insights into the distribution and morphology of trace fossils. However, a significant limitation lies in the challenge of accurately estimating bioturbation intensity from bedding planes. This is in part because current approaches do not establish a connection between bioturbation intensity as seen on bedding planes (plan view) and in cross-section (elevation view). This disconnect complicates the integration of bedding plane assessments into more conventional datasets collected from elevation view. Seventy-seven million Monte Carlo simulations were performed on 11 non-palimpsest Skolithos assemblages, each with varying constraints on burrow length and diameter. These simulations were used to investigate the range and frequency of cross-sectional bioturbation intensities across a spectrum of bedding plane intensities (2-50%). The results show that elevation view bioturbation intensity can be reliably approximated by multiplying plan view bioturbation intensity by the average burrow length relative to the bed thickness, independent of burrow diameter. These findings improve the ichnological analysis of bedding planes for vertical trace fossil assemblages and offer a framework for future research into more complex assemblages.