The Journal of Physical Chemistry A最新文献

{"title":"Ground and First Excited States of the NaSr Molecule: Experimental and Theoretical Study.","authors":"Jacek Szczepkowski, Marcin Gronowski, Matylda Olko, Romain Vexiau, Michał Tomza, Olivier Dulieu, Paweł Kowalczyk, Włodzimierz Jastrzebski","doi":"10.1021/acs.jpca.5c01878","DOIUrl":"10.1021/acs.jpca.5c01878","url":null,"abstract":"<p><p>We report the first spectroscopic investigation of the NaSr molecule. Spectra related to the B(2)²Σ⁺ → X(1)²Σ⁺ transition were observed with partial rotational resolution by thermoluminescence and laser-induced fluorescence techniques. Simultaneously, potential energy curves of the lowest electronic states of NaSr and transition dipole moments were calculated by using two different theoretical approaches. Comparison with theoretical results allowed to interpret the experimental spectra and deduce the salient molecular constants of the X(1)²Σ⁺ and B(2)²Σ⁺ states. Reliability of the employed theoretical methods was tested.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4496-4504"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12105035/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143951578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Hydrogen Bonding on Ultrafast Intersystem Crossing in 7-Diethylaminothiocoumarin.","authors":"Abhijit Dutta, Suman Bhowmik, Sujit Kumar Ghosh, Vaidhyanathan Ramamurthy, Pratik Sen","doi":"10.1021/acs.jpca.5c00901","DOIUrl":"10.1021/acs.jpca.5c00901","url":null,"abstract":"<p><p>Thiocarbonyls exhibit unique photophysical properties, characterized by rapid intersystem crossing (ISC) due to favorable singlet-triplet energetics and enhanced spin-orbit coupling. However, the role of hydrogen bonding in modulating the ISC remains underexplored. This study investigates the effect of solvent-solute hydrogen bonding on the ISC dynamics of 7-(diethylamino)-4-methyl-2-sulfanylidene-2H-chromen-2-one (thiocoumarin 1, TC1) using steady-state and time-resolved spectroscopy, complemented by theoretical calculations. Experimental data reveal that in methanol, hydrogen bonding leads to increased fluorescence quantum yield, prolonged singlet-state lifetime, and reduced triplet yield compared to aprotic acetonitrile. Time-resolved spectroscopy identifies an additional long-lived emissive singlet state in methanol, attributed to a hydrogen-bonded state, which slows ISC. Theoretical calculations demonstrate that hydrogen bonding alters the electronic structure and constrains ISC along key nuclear coordinates, including the C═S bond vibration and dihedral angles, leading to decreased triplet formation. These findings provide mechanistic insights into hydrogen-bonding-mediated control of ISC in thiocoumarins, with implications for designing functional materials with tunable photophysical properties.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4414-4425"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143955964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deciphering the Structural and Electronic Properties of RuSi₃^-/0 Clusters: Insights from Anion Photoelectron Spectroscopy and Theoretical Analysis.","authors":"Sheng-Jie Lu, Zhong-Xin Sun","doi":"10.1021/acs.jpca.5c01905","DOIUrl":"10.1021/acs.jpca.5c01905","url":null,"abstract":"<p><p>Transition metal (TM) silicides have attracted significant attention in materials science due to their desirable physical properties and varied applications across industries ranging from microelectronics to catalysis. This study uniquely explores the structural and bonding characteristics of ruthenium-doped silicon clusters, specifically RuSi₃, presenting new experimental and computational insights into these anionic and neutral species. Mass-selected photoelectron spectroscopy, alongside advanced theoretical techniques including density functional theory (DFT) and high-precision coupled cluster (CCSD(T)) methods, was employed to probe the electronic structures and energetic properties of RuSi₃^- anion and its neutral counterpart. The results reveal the presence of multiple isomers within RuSi₃^-, characterized by distinct electronic configurations, and show a strong correlation between experimental and theoretical vertical detachment energy (VDE). Notably, the findings indicate that the covalent interactions and charge distributions in these clusters significantly influence their stability and reactivity.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4505-4512"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143951611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Phase-Space Electronic Hamiltonian for Molecules in a Static Magnetic Field II: Quantum Chemistry Calculations with Gauge Invariant Atomic Orbitals.","authors":"Mansi Bhati, Zhen Tao, Xuezhi Bian, Jonathan Rawlinson, Robert Littlejohn, Joseph E Subotnik","doi":"10.1021/acs.jpca.4c07905","DOIUrl":"10.1021/acs.jpca.4c07905","url":null,"abstract":"<p><p>In a companion paper, we have developed a phase-space electronic structure theory of molecules in magnetic fields, whereby the electronic energy levels arise from diagonalizing a phase-space Hamiltonian <i>Ĥ</i>_PS(<b>X</b>, <b>P</b>, <b>G</b>, <b>B</b>) that depends parametrically on nuclear position and momentum. The resulting eigenvalues are translationally invariant; moreover, if the magnetic field is in the <i>z</i>-direction, then the eigenvalues are also invariant to rotations around the <i>z</i>-direction. However, like all Hamiltonians in a magnetic field, the theory has a gauge degree of freedom (corresponding to the position of the magnetic origin in the vector potential), and requires either (i) formally, a complete set of electronic states or (ii) in practice, gauge-invariant atomic orbitals (GIAOs) in order to realize such translational and rotational invariance. Here we describe how to implement a phase-space electronic Hamiltonian using GIAOs within a practical electronic structure package (in our case, Q-Chem). We further show that novel phenomena can be observed with finite <b>B</b>-fields, including minimum energy structures with <b>Π</b>_min ≠ 0, indicating nonzero electronic motion in the ground-state.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4573-4590"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143952467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid Discovery of Graphene Nanoflakes with Desired Absorption Spectra Using DFT and Bayesian Optimization with Neural Network Kernel.","authors":"Şener Özönder, Hatice Kübra Küçükkartal","doi":"10.1021/acs.jpca.5c00405","DOIUrl":"10.1021/acs.jpca.5c00405","url":null,"abstract":"<p><p>Grid searching a large and high-dimensional chemical space with density functional theory (DFT) to discover new materials with desired properties is prohibitive due to the high computational cost. We propose an approach utilizing Bayesian optimization (BO) with an artificial neural network kernel to enable an efficient and low-cost guided search on the chemical space, avoiding costly brute-force grid search. This method leverages the BO algorithm, where the kernel neural network trained on a limited number of DFT results determines the most promising regions of the chemical space to explore in subsequent iterations. This approach aims to discover new materials with target properties while minimizing the number of DFT calculations required. To demonstrate the effectiveness of this method, we investigated 63 doped graphene quantum dots (GQDs) with sizes ranging from 1 to 2 nm to find the structure with the highest light absorption. Using time-dependent DFT (TDDFT) only 12 times, we achieved a significant reduction in computational cost, approximately 20% of what would be required for a full grid search. Considering that TDDFT calculations for a single GQD require about half a day of wall time on high-performance computing nodes, this reduction is substantial. Our approach can be generalized to the discovery of new drugs, chemicals, crystals, and alloys in high-dimensional and large chemical spaces, offering a scalable solution enabled by the neural network kernel.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4591-4600"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143952825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Room Temperature Gas-Phase Detection and Formation Gibbs Energy of the Water Dimethyl Ether Bimolecular Complex.","authors":"Alexander Kjaersgaard, Dhritabrata Pal, Emil Vogt, Tine Elmelund Skovbo, Henrik G Kjaergaard","doi":"10.1021/acs.jpca.5c01130","DOIUrl":"10.1021/acs.jpca.5c01130","url":null,"abstract":"<p><p>Hydrated complexes are of general interest for understanding nucleation processes in the atmosphere, where water is abundant, especially as the role of whether water enhances or inhibits nucleation is still uncertain. We have recorded the Fourier transform infrared absorption spectrum of the water dimethyl ether bimolecular complex in the gas phase at room temperature. Four distinct bands are observed and assigned. The equilibrium constant of complex formation is determined from the experimental integrated absorbance of the bands and the corresponding calculated intensities. The calculated band intensities are obtained with a 9D reduced-dimensional variational local mode model with the CCSD(T)-F12a/cc-pVDZ-F12 potential energy and dipole moment surfaces. A similar equilibrium constant for a majority of the observed bands is obtained, with an average value of 0.042 ± 0.003 at <i>T</i> = 298 K. The water dimethyl ether complex studied here is similar to the water dimer, and our determined equilibrium constant may serve as a reasonable estimate for that of water dimer, which is especially relevant in atmospheric chemistry.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4438-4446"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143952827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal Stability Difference between NQ and NOG: Insights from Pyrolysis Reactions via First-Principles Molecular Dynamic and Quantum Chemistry Modeling.","authors":"Shuangfei Zhu, Yao Li, Enliang Liu, Yang Liu, Ruijun Gou, Shuhai Zhang","doi":"10.1021/acs.jpca.5c00533","DOIUrl":"10.1021/acs.jpca.5c00533","url":null,"abstract":"<p><p>The thermal stability differences between NQ and NOG were investigated by examining their initial decomposition mechanisms at both the molecular and crystalline scales using density functional theory calculations. First-principles molecular dynamics simulations revealed that NQ primarily undergoes intermolecular hydrogen or oxygen atom transfer reactions, while NOG preferentially decomposes through a ring-opening reaction. Analysis of decomposition product evolution demonstrated that NQ decomposes faster at high temperatures, with the decomposition products of both compounds being strongly dependent on their molecular structures. Quantum chemistry calculations showed that NOG molecules exhibit higher energy barriers for the same unimolecular decomposition pathways compared to NQ. Furthermore, two reversible reactions, hydrogen transfer and bond rotation, were identified as key factors enhancing NOG's thermal stability. These findings significantly advance our understanding of structure-property relationships in energetic materials while providing valuable insights into studying energy release mechanisms and designing novel energetic compounds.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4394-4404"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143955523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probing Host-Guest Interactions of the Dual Anion Receptor Harmane with Halide and HSO₄^- Anions.","authors":"Xiao-Fei Gao, Wenjin Cao, Xue-Bin Wang","doi":"10.1021/acs.jpca.5c01523","DOIUrl":"10.1021/acs.jpca.5c01523","url":null,"abstract":"<p><p>Harmane is a polycyclic amine that can recognize F^- and HSO₄^- via the ═N-H or ≡N binding site. The active binding site depends on whether the solvent is protic or aprotic, but the underlying molecular mechanism remains unclear. As a first step toward obtaining such mechanisms in solutions, we investigated the interactions of harmane with halide anions (F^-, Cl^-, Br^-, and I^-) and HSO₄^- in the gas phase using negative ion photoelectron spectroscopy combined with theoretical calculations. The adiabatic/vertical detachment energies for deprotonated harmane and harmane·X^- (X = F, Cl, Br, I, and HSO₄) were determined to be 2.72/2.79, 3.25/3.38, 4.19/4.43, 4.35/4.40, 3.93/3.99, and 4.49/4.75 eV, respectively, with an uncertainty of ±0.05 eV. All the X^- anions were found to form hydrogen bonds with harmane through the ═N-H site. A nearly complete proton transfer was observed within the harmane·F^- complex anion. Larger halide anions in other harmane-halide complexes remain relatively intact. Four closely lying isomers of harmane·HSO₄^- were identified. The photodetachment locations of the harmane complex anions were also revealed by electronic state calculations and molecular orbital analyses. The current work lays out a foundation for future work on microsolvated clusters to probe how solvent molecules influence the harmane-anion binding motif.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4480-4487"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143955586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oxygen Dependence on Hydrated Electron Yields: Pulsed Radiolysis Studies Using Proton Beams.","authors":"Sarra Terfas, Guillaume Blain, Emeline Craff, Charbel Koumeir, Ferid Haddad, Freddy Poirier, Gregory Delpon, Johan Vandenborre","doi":"10.1021/acs.jpca.5c00629","DOIUrl":"https://doi.org/10.1021/acs.jpca.5c00629","url":null,"abstract":"<p><p>Understanding the yield and kinetics of the hydrated electron (e^-_aq) is critical for applications in both biological and chemical systems, especially in the context of innovative FLASH radiation therapy. Most studies have employed chemical scavenging methods to measure radical yields. Although these techniques have undeniable advantages, such as probing early processes down to nanosecond time scale, and are easy to implement, they also have significant limitations. The main one is that they are not appropriate to longer time scales, especially the microsecond one, which is a key part of the homogeneous chemistry stage. Direct measurements of hydrated electron using pulsed ion beams are rare, especially with lighter particles such as protons used in radiotherapy, mainly due to instrumental complexity. This study addresses this gap by employing a dedicated time-resolved UV-visible absorption spectrometer coupled to a pulsed ion beam to measure transient hydrated electron radiolytic yield (<i>G</i>-value) in pure water, under both aerated and deaerated conditions. Pulsed radiolysis experiments were conducted at the Arronax cyclotron facility (Nantes, France) with a 68 MeV extracted H⁺ ion beam under ultra-high-dose rate (UHDR) conditions. The pulsed proton beam provides a radiolytic yield at <i>t</i> = 2 μs as well as e^-_aq formation and decay times. The results present the following track segment (TS) yields <b><i>G</i></b>_{<b>TS_2μ<i>s</i></b>}(e^-_aq) = (1.00 ± 0.17) × 10^-7 mol·J^-1 under deaerated conditions (≤0.04% O₂) with a half-life of 8.8 ± 1.5 μs, and <b><i>G</i></b>_{<b>TS_2μ<i>s</i></b>}(e^-_aq) = (0.90 ± 0.20) × 10^-7 mol·J^-1, <b><i>G</i></b>_{<b>TS_2μ<i>s</i></b>}(e^-_aq) = (0.62 ± 0.24)×10^-7 mol·J^-1, and <b><i>G</i></b>_{<b>TS_2μ<i>s</i></b>}(e^-_aq) = (0.13 ± 0.04) × 10^-7 mol·J^-1 under oxygen concentrations of 0.4, 1, and 21% O₂, respectively. These results represent the yields measured directly at the homogeneous chemistry stage, without the use of scavengers, and offer new data within several oxygen contents, allowing a better understanding of the dependence of oxygen on <i>G</i>_TS(e^-_aq). They are essential to explore UHDR chemistry dedicated to FLASH radiation therapy and to produce reliable data to validate Monte Carlo codes, such as Geant4-DNA and Topas-nBio.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144118341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"OH Roaming as a Key Pathway in the Anti-CH₃CHOO + H₂O Reaction Yielding CH₃COOH and H₂O.","authors":"Lijie Liu, Hao Wu, Yanlin Fu, Xiaoxiao Lu, Xingan Wang, Dong H Zhang, Bina Fu","doi":"10.1021/acs.jpca.5c00449","DOIUrl":"10.1021/acs.jpca.5c00449","url":null,"abstract":"<p><p>The reaction of <i>anti</i>-CH₃CHOO with H₂O is a crucial atmospheric process, resulting in the end products CH₃COOH + H₂O through the dissociation of the intermediate hydroxyethyl hydroperoxide (CH₃CH(HO)OOH, HEHP). Based on an accurate full-dimensional PES, we have obtained detailed dynamics information for this reaction through quasi-classical trajectory simulations. We report two reaction mechanisms for the CH₃COOH + H₂O product channel: one involving a direct mechanism through the transition state and the other an intriguing OH roaming mechanism. The roaming pathway proceeds via the dissociation of HEHP into OH and the hydroxyethoxy radical (CH₃CH(HO)O, HEO), where the OH radical roams near HEO and abstracts a hydrogen atom, subsequently forming H₂O and CH₃COOH. The presence of this roaming pathway significantly increases the yield of CH₃COOH + H₂O. This work provides new dynamical support for the study of the <i>anti</i>-CH₃CHOO + H₂O reaction and enriches our understanding of atmospheric chemistry.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4364-4373"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143956099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}