ACS Physical Chemistry Au最新文献

{"title":"“Button-on-a-String” Mechanism in Water, the Ultrafast UV-to-Heat Conversion by Mycosporine-like Amino Acid Porphyra-334 of Natural Sunscreen Compound","authors":"Makoto Hatakeyama*,&nbsp; and ,&nbsp;Shinichiro Nakamura,&nbsp;","doi":"10.1021/acsphyschemau.4c0010710.1021/acsphyschemau.4c00107","DOIUrl":"https://doi.org/10.1021/acsphyschemau.4c00107https://doi.org/10.1021/acsphyschemau.4c00107","url":null,"abstract":"<p >Mycosporine-like amino acids (MAAs) are a family of hydrophilic sunscreen compounds synthesized by aquatic organisms, such as algae and cyanobacteria. In this study, we demonstrate that porphyra-334, which is a common MAA, decays nonradiatively within several hundred femtoseconds after ultraviolet (UV) light absorption in water by rotating the intramolecular cyclohexenimine ring. The ring rotation resulted from the UV excitation of the intramolecular π-conjugation, and the ring rotation proceeded while preserving the hydrogen bonds with the surrounding water molecules. The hydrogen bonds were preserved due to the structural flexibility of the ring-attached amino acids of porphyra-334. The amino acids maintained their center of mass positions during the ring-rotating nonradiative decay. The amino acids and cyclohexenimine ring are analogous to the string and button of a button-on-a-string spinner, otherwise known as button whirligigs. Thus, we refer to the ring-rotating nonradiative decay of porphyra-334 as a button-on-a-string mechanism. We also show that this mechanism results from porphyra-334 itself rather than from the surrounding water molecules. The present results indicate that the molecular “spinner” exists in aquatic organisms and protects them from UV with the aid of water.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"5 3","pages":"274–282 274–282"},"PeriodicalIF":3.7,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsphyschemau.4c00107","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144146483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Celebrating 5 Years of the ACS Au Journal Family","authors":"Paul D. Goring,&nbsp;Amelia Newman,&nbsp;Christopher W. Jones* and Shelley D. Minteer*,&nbsp;","doi":"10.1021/acsphyschemau.5c0001110.1021/acsphyschemau.5c00011","DOIUrl":"https://doi.org/10.1021/acsphyschemau.5c00011https://doi.org/10.1021/acsphyschemau.5c00011","url":null,"abstract":"","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"5 2","pages":"112–114 112–114"},"PeriodicalIF":3.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsphyschemau.5c00011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143696369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Celebrating 5 Years of the ACS Au Journal Family.","authors":"Paul D Goring, Amelia Newman, Christopher W Jones, Shelley D Minteer","doi":"10.1021/acsphyschemau.5c00011","DOIUrl":"https://doi.org/10.1021/acsphyschemau.5c00011","url":null,"abstract":"","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"5 2","pages":"112-114"},"PeriodicalIF":3.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11950843/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143754838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoabsorption and Photoionization Cross-Sections and Asymmetry Parameters of Pyrrole in the Vacuum-Ultraviolet Energy Range","authors":"Mariana B. M. S. Medeiros,&nbsp;Josenilton N. Sousa,&nbsp;Manuela S. Arruda,&nbsp;Milton M. Fujimoto,&nbsp;Manoel G. P. Homem,&nbsp;Helder K. Tanaka,&nbsp;Bruno Credidio,&nbsp;Ricardo R. T. Marinho and Frederico V. Prudente*,&nbsp;","doi":"10.1021/acsphyschemau.4c0010110.1021/acsphyschemau.4c00101","DOIUrl":"https://doi.org/10.1021/acsphyschemau.4c00101https://doi.org/10.1021/acsphyschemau.4c00101","url":null,"abstract":"<p >We carried out a joint experimental and theoretical investigation of the interaction of vacuum-ultraviolet radiation with pyrrole molecules in the gas phase. A double-ion chamber spectrometer was used to measure the absolute photoabsorption cross-sections and the photoionization quantum yields from the ionization threshold to 21.5 eV using synchrotron radiation. Moreover, photoionization and neutral-decay cross-sections on an absolute scale were derived directly from the measured data. In addition, theoretical results of the photoionization cross-section (PICS) and asymmetric parameters were obtained from the ionization threshold to 50.0 eV considering all valence orbitals. These calculations were performed using the Padé approximant technique to solve the Lippmann–Schwinger equation at the static-exchange (SE) and static-exchange-polarization (SEP) levels of approximation. Comparisons are also made with the experimental and theoretical data available in the literature. We report, for the first time, experimental ionization efficiency, neutral decay cross-sections, theoretical photoionization cross-sections for each valence orbital, and several asymmetry parameters. In general, the results are consistent and in good agreement with the available data.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"5 3","pages":"254–265 254–265"},"PeriodicalIF":3.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsphyschemau.4c00101","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144146510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoabsorption and Photoionization Cross-Sections and Asymmetry Parameters of Pyrrole in the Vacuum-Ultraviolet Energy Range.","authors":"Mariana B M S Medeiros, Josenilton N Sousa, Manuela S Arruda, Milton M Fujimoto, Manoel G P Homem, Helder K Tanaka, Bruno Credidio, Ricardo R T Marinho, Frederico V Prudente","doi":"10.1021/acsphyschemau.4c00101","DOIUrl":"10.1021/acsphyschemau.4c00101","url":null,"abstract":"<p><p>We carried out a joint experimental and theoretical investigation of the interaction of vacuum-ultraviolet radiation with pyrrole molecules in the gas phase. A double-ion chamber spectrometer was used to measure the absolute photoabsorption cross-sections and the photoionization quantum yields from the ionization threshold to 21.5 eV using synchrotron radiation. Moreover, photoionization and neutral-decay cross-sections on an absolute scale were derived directly from the measured data. In addition, theoretical results of the photoionization cross-section (PICS) and asymmetric parameters were obtained from the ionization threshold to 50.0 eV considering all valence orbitals. These calculations were performed using the Padé approximant technique to solve the Lippmann-Schwinger equation at the static-exchange (SE) and static-exchange-polarization (SEP) levels of approximation. Comparisons are also made with the experimental and theoretical data available in the literature. We report, for the first time, experimental ionization efficiency, neutral decay cross-sections, theoretical photoionization cross-sections for each valence orbital, and several asymmetry parameters. In general, the results are consistent and in good agreement with the available data.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"5 3","pages":"254-265"},"PeriodicalIF":3.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12123551/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144200234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural Elucidation of Lithium Borate Glasses Using XRD, FTIR, and EPR Spectroscopy.","authors":"Mohamed A Morsy, Thomas F Garrison, Michael R Kessler, Mohammad H A Mhareb, Hosny Zahr El-Deen","doi":"10.1021/acsphyschemau.4c00106","DOIUrl":"10.1021/acsphyschemau.4c00106","url":null,"abstract":"<p><p>A detailed investigation of the structural changes of lithium borate (LiB) glass 25Li₂O-(75 - <i>x</i>)B₂O₃ was conducted in the absence and presence of lead(II) oxide or aluminum oxide (<i>x</i> = 10 mol %) glass modifiers. X-ray diffraction (XRD), Fourier transform infrared (FTIR), and electron paramagnetic resonance (EPR) spectroscopy were used to explore the structural properties of LiB glass by incorporating trace amounts of manganese(III) oxide (0.00-0.25 mol %) as a probe. Differential thermal analysis and XRD results for the glasses and their ceramics confirmed the integration of aluminum atoms into the glass framework by forming a lithium aluminum boron oxide Li₂(AlB₅O₁₀) crystalline phase. Lead atoms were located interstitially, which disordered the borate glass structure and produced a lithium tetraborate crystalline phase. Semiempirical modeling of the glass structures was conducted to estimate the fundamental vibrational modes of the glass materials using a parametric method 3 (PM3MM) with molecular mechanics corrections to elucidate the geometry of the borate (BO₃) groups and their possible vibrational modes. Our analysis revised the conventional representation of the tetrahedral BO₄ units, which were not observed, to \"distorted-trigonal\" BO₃ groups and associated with nonbridging oxygen (NBO) atoms. EPR spectroscopy established a link between the NBO in oxides and the well-defined peak at <i>g</i>-factor ∼4.2 in glass materials, which had been assigned to iron(III) ions according to the literature.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"5 2","pages":"227-238"},"PeriodicalIF":3.7,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11950853/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143754581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superior Oxygen Exchange Kinetics on Bi₂O₃-Based Mixed Conducting Composites.","authors":"Linn Katinka Emhjellen, Vincent Thoréton, Wen Xing, Reidar Haugsrud","doi":"10.1021/acsphyschemau.4c00111","DOIUrl":"10.1021/acsphyschemau.4c00111","url":null,"abstract":"<p><p>The kinetics of oxygen exchange dictate the rate of redox reactions, which is crucial for electrochemical-based sustainable technologies. In this study, we use isotope exchange pulse responses to elucidate the oxygen exchange mechanism for (Bi_0.8Tm_0.2)₂O_3-δ (BTM)-(La_0.8Sr_0.2)_0.99MnO_3-δ (LSM) composites. With an optimized composition and microstructure, these composites can achieve polarization resistances below 0.01 Ω·cm² at 700 °C. Analysis of the oxygen exchange rate, , by splitting it into elementary processes using the serial two-step scheme, demonstrates that both the dissociative adsorption and incorporation of oxygen are accelerated in BTM-LSM compared to the parent phases. Dissociative adsorption of molecular oxygen is rate-limiting below 900 °C in the range 0.002-0.05 atm O₂ and below 850 °C in 0.21 atm O₂. Cation interdiffusion or changes in the electronic structure at the interface between the two materials create an electrocatalytically active region spanning 1-40 nm around the BTM-LSM phase boundary. Oxygen exchange coefficients within this region were estimated to be 2-3 orders of magnitude higher compared to those of the entire composite surface. We propose two potential pathways for oxygen exchange in BTM-LSM, with calculated <i>p</i> _O₂ dependencies for each rate-determining step (<i>rds</i>). The <i>p</i> _O₂ dependency of reveals that molecular oxygen is involved in the <i>rds</i>.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"5 2","pages":"239-248"},"PeriodicalIF":3.7,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11950862/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143754584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural Elucidation of Lithium Borate Glasses Using XRD, FTIR, and EPR Spectroscopy","authors":"Mohamed A. Morsy*,&nbsp;Thomas F. Garrison,&nbsp;Michael R. Kessler,&nbsp;Mohammad H. A. Mhareb and Hosny Zahr El-Deen,&nbsp;","doi":"10.1021/acsphyschemau.4c0010610.1021/acsphyschemau.4c00106","DOIUrl":"https://doi.org/10.1021/acsphyschemau.4c00106https://doi.org/10.1021/acsphyschemau.4c00106","url":null,"abstract":"<p >A detailed investigation of the structural changes of lithium borate (LiB) glass 25Li₂O-(75 – <i>x</i>)B₂O₃ was conducted in the absence and presence of lead(II) oxide or aluminum oxide (<i>x</i> = 10 mol %) glass modifiers. X-ray diffraction (XRD), Fourier transform infrared (FTIR), and electron paramagnetic resonance (EPR) spectroscopy were used to explore the structural properties of LiB glass by incorporating trace amounts of manganese(III) oxide (0.00–0.25 mol %) as a probe. Differential thermal analysis and XRD results for the glasses and their ceramics confirmed the integration of aluminum atoms into the glass framework by forming a lithium aluminum boron oxide Li₂(AlB₅O₁₀) crystalline phase. Lead atoms were located interstitially, which disordered the borate glass structure and produced a lithium tetraborate crystalline phase. Semiempirical modeling of the glass structures was conducted to estimate the fundamental vibrational modes of the glass materials using a parametric method 3 (PM3MM) with molecular mechanics corrections to elucidate the geometry of the borate (BO₃) groups and their possible vibrational modes. Our analysis revised the conventional representation of the tetrahedral BO₄ units, which were not observed, to “distorted-trigonal” BO₃ groups and associated with nonbridging oxygen (NBO) atoms. EPR spectroscopy established a link between the NBO in oxides and the well-defined peak at <i>g</i>-factor ∼4.2 in glass materials, which had been assigned to iron(III) ions according to the literature.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"5 2","pages":"227–238 227–238"},"PeriodicalIF":3.7,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsphyschemau.4c00106","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143696327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superior Oxygen Exchange Kinetics on Bi2O3-Based Mixed Conducting Composites","authors":"Linn Katinka Emhjellen,&nbsp;Vincent Thoréton,&nbsp;Wen Xing and Reidar Haugsrud*,&nbsp;","doi":"10.1021/acsphyschemau.4c0011110.1021/acsphyschemau.4c00111","DOIUrl":"https://doi.org/10.1021/acsphyschemau.4c00111https://doi.org/10.1021/acsphyschemau.4c00111","url":null,"abstract":"<p >The kinetics of oxygen exchange dictate the rate of redox reactions, which is crucial for electrochemical-based sustainable technologies. In this study, we use isotope exchange pulse responses to elucidate the oxygen exchange mechanism for (Bi_0.8Tm_0.2)₂O_3−δ (BTM)–(La_0.8Sr_0.2)_0.99MnO_3−δ (LSM) composites. With an optimized composition and microstructure, these composites can achieve polarization resistances below 0.01 Ω·cm² at 700 °C. Analysis of the oxygen exchange rate, <span><img></span>, by splitting it into elementary processes using the serial two-step scheme, demonstrates that both the dissociative adsorption and incorporation of oxygen are accelerated in BTM–LSM compared to the parent phases. Dissociative adsorption of molecular oxygen is rate-limiting below 900 °C in the range 0.002–0.05 atm O₂ and below 850 °C in 0.21 atm O₂. Cation interdiffusion or changes in the electronic structure at the interface between the two materials create an electrocatalytically active region spanning 1–40 nm around the BTM–LSM phase boundary. Oxygen exchange coefficients within this region were estimated to be 2–3 orders of magnitude higher compared to those of the entire composite surface. We propose two potential pathways for oxygen exchange in BTM–LSM, with calculated <i>p</i>_O₂ dependencies for each rate-determining step (<i>rds</i>). The <i>p</i>_O₂ dependency of <span><img></span> reveals that molecular oxygen is involved in the <i>rds</i>.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"5 2","pages":"239–248 239–248"},"PeriodicalIF":3.7,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsphyschemau.4c00111","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143696328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In Spite of the Chemist's Belief: Metastable Hydrates of CsCl.","authors":"Kamila Závacká, Ľubica Vetráková, Johannes Bachler, Vilém Neděla, Thomas Loerting","doi":"10.1021/acsphyschemau.4c00093","DOIUrl":"10.1021/acsphyschemau.4c00093","url":null,"abstract":"<p><p>In this work, we focus on the low-temperature behavior of concentrated aqueous solutions of cesium chloride and discover two hydrates of CsCl. We employ four different methods, namely, (i) simple cooling at rates between 0.5 and 80 K s^-1, (ii) simple cooling followed by pressurization, (iii) hyperquenching at 10⁶ to 10⁷ K s^-1, and (iv) hyperquenching followed by pressurization. Depending on the method, different types of phase behaviors are observed, which encompass crystallization involving freeze-concentration, pressure-induced amorphization, full vitrification, and polyamorphic transformation. The CsCl hydrates discovered in our work cold-crystallize above 150 K upon heating after ultrafast vitrification (routes iii and iv) and show melting temperatures <i>below</i> the eutectic temperature of 251 K. We determine the composition of these hydrates to be CsCl·5H₂O and CsCl·6H₂O and find evidence for their existence in ESEM, calorimetry, and X-ray diffraction. The dominant and less metastable hydrate is the hexahydrate, where the pentahydrate appears as a minority species. We also reveal the birthplace for the CsCl hydrates, namely, the freeze-concentrated solution (FCS) formed upon cold-crystallization of the fully glassy solution (from iii and iv). The spongy FCS produced upon <i>cooling</i> of the liquid (from i and ii) is incapable of crystallizing CsCl-hydrates. By contrast, the FCS produced upon <i>heating</i> the glassy solution (from iii and iv) shows tiny, fine features that are capable of crystallizing CsCl-hydrates. Our findings contradict the current knowledge that alkali chlorides only have hydrates for the smaller cations Li⁺ and Na⁺, but not for the larger cations K⁺, Rb⁺, and Cs⁺ and pave the way for future determination of CsCl-hydrate crystal structures. The pathway to metastable crystalline materials outlined here might be more generally applicable and found in nature, e.g., in comets or on interstellar dust grains, when glassy aqueous solutions crystallize upon heating.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"5 2","pages":"195-206"},"PeriodicalIF":3.7,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11950848/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143754556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}