Structural Dynamics-Us最新文献

{"title":"Structure determination of the tetracene dimer in helium nanodroplets using femtosecond strong-field ionization.","authors":"Constant Schouder,&nbsp;Adam S Chatterley,&nbsp;Florent Calvo,&nbsp;Lars Christiansen,&nbsp;Henrik Stapelfeldt","doi":"10.1063/1.5118005","DOIUrl":"https://doi.org/10.1063/1.5118005","url":null,"abstract":"<p><p>Dimers of tetracene molecules are formed inside helium nanodroplets and identified through covariance analysis of the emission directions of kinetic tetracene cations stemming from femtosecond laser-induced Coulomb explosion. Next, the dimers are aligned in either one or three dimensions under field-free conditions by a nonresonant, moderately intense laser pulse. The experimental angular covariance maps of the tetracene ions are compared to calculated covariance maps for seven different dimer conformations and found to be consistent with four of these. Additional measurements of the alignment-dependent strong-field ionization yield of the dimer narrow the possible conformations down to either a slipped-parallel or parallel-slightly rotated structure. According to our quantum chemistry calculations, these are the two most stable gas-phase conformations of the dimer and one of them is favorable for singlet fission.</p>","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":"6 4","pages":"044301"},"PeriodicalIF":2.8,"publicationDate":"2019-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5118005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41216718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the multiparameter nature of EUV-visible wave mixing at the FERMI FEL.","authors":"L Foglia,&nbsp;F Capotondi,&nbsp;H Höppner,&nbsp;A Gessini,&nbsp;L Giannessi,&nbsp;G Kurdi,&nbsp;I Lopez Quintas,&nbsp;C Masciovecchio,&nbsp;M Kiskinova,&nbsp;R Mincigrucci,&nbsp;D Naumenko,&nbsp;I P Nikolov,&nbsp;E Pedersoli,&nbsp;G M Rossi,&nbsp;A Simoncig,&nbsp;F Bencivenga","doi":"10.1063/1.5111501","DOIUrl":"https://doi.org/10.1063/1.5111501","url":null,"abstract":"<p><p>The rapid development of extreme ultraviolet (EUV) and x-ray ultrafast coherent light sources such as free electron lasers (FELs) has triggered the extension of wave-mixing techniques to short wavelengths. This class of experiments, based on the interaction of matter with multiple light pulses through the <i>N</i>th order susceptibility, holds the promise of combining intrinsic ultrafast time resolution and background-free signal detection with nanometer spatial resolution and chemical specificity. A successful approach in this direction has been the combination of the unique characteristics of the seeded FEL FERMI with dedicated four-wave-mixing (FWM) setups, which leads to the demonstration of EUV-based transient grating (TG) spectroscopy. In this perspective paper, we discuss how the TG approach can be extended toward more general FWM spectroscopies by exploring the intrinsic multiparameter nature of nonlinear processes, which derives from the ability of controlling the properties of each field independently.</p>","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":"6 4","pages":"040901"},"PeriodicalIF":2.8,"publicationDate":"2019-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5111501","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41216717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FACT and FAIR with Big Data allows objectivity in science: The view of crystallography","authors":"J. Helliwell","doi":"10.1063/1.5124439","DOIUrl":"https://doi.org/10.1063/1.5124439","url":null,"abstract":"A publication is an important narrative of the work done and interpretations made by researchers securing a scientific discovery. As The Royal Society neatly states though, “Nullius in verba” (“Take nobody's word for it”), whereby the role of the underpinning data is paramount. Therefore, the objectivity that preserving that data within the article provides is due to readers being able to check the calculation decisions of the authors. But how to achieve full data archiving? This is the raw data archiving challenge, in size and need for correct metadata. Processed diffraction data and final derived molecular coordinates archiving in crystallography have achieved an exemplary state of the art relative to most fields. One can credit IUCr with developing exemplary peer review procedures, of narrative, underpinning structure factors and coordinate data and validation report, through its checkcif development and submission system introduced for Acta Cryst. C and subsequently developed for its other chemistry journals. The crystallographic databases likewise have achieved amazing success and sustainability these last 50 years or so. The wider science data scene is celebrating the FAIR data accord, namely, that data be Findable, Accessible, Interoperable, and Reusable [Wilkinson et al., “Comment: The FAIR guiding principles for scientific data management and stewardship,” Sci. Data 3, 160018 (2016)]. Some social scientists also emphasize more than FAIR being needed, the data should be “FACT,” which is an acronym meaning Fair, Accurate, Confidential, and Transparent [van der Aalst et al., “Responsible data science,” Bus Inf. Syst. Eng. 59(5), 311–313 (2017)], this being the issue of ensuring reproducibility not just reusability. (Confidentiality of data not likely being relevant to our data obviously.) Acta Cryst. B, C, E, and IUCrData are the closest I know to being both FACT and FAIR where I repeat for due emphasis: the narrative, the automatic “general” validation checks, and the underpinning data are checked thoroughly by subject specialists (i.e., the specialist referees). IUCr Journals are also the best that I know of for encouraging and then expediting the citation of the DOI for a raw diffraction dataset in a publication; examples can be found in IUCrJ, Acta Cryst D, and Acta Cryst F. The wish for a checkcif for raw diffraction data has been championed by the IUCr Diffraction Data Deposition Working Group and its successor, the IUCr Committee on Data.","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2019-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5124439","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46383757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time resolved transient circular dichroism spectroscopy using synchrotron natural polarization","authors":"François Auvray, D. Dennetiere, A. Giuliani, F. Jamme, F. Wien, B. Nay, S. Zirah, F. Polack, C. Menneglier, B. Lagarde, J. Hirst, M. Réfrégiers","doi":"10.1063/1.5120346","DOIUrl":"https://doi.org/10.1063/1.5120346","url":null,"abstract":"Ultraviolet (UV) synchrotron radiation circular dichroism (SRCD) spectroscopy has made an important contribution to the determination and understanding of the structure of bio-molecules. In this paper, we report an innovative approach that we term time-resolved SRCD (tr-SRCD), which overcomes the limitations of current broadband UV SRCD setups. This technique allows accessing ultrafast time scales (down to nanoseconds), previously measurable only by other methods, such as infrared (IR), nuclear magnetic resonance (NMR), fluorescence and absorbance spectroscopies, and small angle X-ray scattering (SAXS). The tr-SRCD setup takes advantage of the natural polarization of the synchrotron radiation emitted by a bending magnet to record broadband UV CD faster than any current SRCD setup, improving the acquisition speed from 10 mHz to 130 Hz and the accessible temporal resolution by several orders of magnitude. We illustrate the new approach by following the isomer concentration changes of an azopeptide after a photoisomerization. This breakthrough in SRCD spectroscopy opens up a wide range of potential applications to the detailed characterization of biological processes, such as protein folding and protein-ligand binding.","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2019-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5120346","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42006560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hole dynamics in a photovoltaic donor-acceptor couple revealed by simulated time-resolved X-ray absorption spectroscopy","authors":"Khadijeh Khalili, L. Inhester, C. Arnold, R. Welsch, J. W. Andreasen, R. Santra","doi":"10.1063/1.5097653","DOIUrl":"https://doi.org/10.1063/1.5097653","url":null,"abstract":"Theoretical and experimental methodologies that can characterize electronic and nuclear dynamics, and the coupling between the two, are needed to understand photoinduced charge transfer in molecular building blocks used in organic photovoltaics. Ongoing developments in ultrafast pump-probe techniques such as time-resolved X-ray absorption spectroscopy, using an X-ray free electron laser in combination with an ultraviolet femtosecond laser, present desirable probes of coupled electronic and nuclear dynamics. In this work, we investigate the charge transfer dynamics of a donor-acceptor pair, which is widely used as a building block in low bandgap block copolymers for organic photovoltaics. We simulate the dynamics of the benzothiadiazole-thiophene molecule upon photoionization with a vacuum ultraviolet (VUV) pulse and study the potential of probing the subsequent charge dynamics using time-resolved X-ray absorption spectroscopy. The photoinduced dynamics are calculated using on-the-fly nonadiabatic molecular dynamics simulations based on Tully's Fewest Switches Surface Hopping approach. We calculate the X-ray absorption spectrum as a function of time after ionization at the Hartree-Fock level. The changes in the time-resolved X-ray absorption spectrum at the sulfur K-edge reveal the ultrafast charge carrier dynamics in the molecule occurring on a femtosecond time scale. These theoretical findings anticipate that ultrafast time-resolved X-ray absorption spectroscopy using an X-ray probe in combination with a VUV pump offers a new approach to investigate the detailed dynamics of organic photovoltaic materials.","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5097653","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46409219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Is radiation damage the limiting factor in high-resolution single particle imaging with X-ray free-electron lasers?","authors":"C. Östlin, N. Tîmneanu, C. Caleman, A. V. Martin","doi":"10.1063/1.5098309","DOIUrl":"https://doi.org/10.1063/1.5098309","url":null,"abstract":"The prospect of single particle imaging with atomic resolution is one of the scientific drivers for the development of X-ray free-electron lasers. The assumption since the beginning has been that damage to the sample caused by intense X-ray pulses is one of the limiting factors for achieving subnanometer X-ray imaging of single particles and that X-ray pulses need to be as short as possible. Based on the molecular dynamics simulations of proteins in X-ray fields of various durations (5 fs, 25 fs, and 50 fs), we show that the noise in the diffracted signal caused by radiation damage is less than what can be expected from other sources, such as sample inhomogeneity and X-ray shot-to-shot variations. These findings show a different aspect of the feasibility of high-resolution single particle imaging using free-electron lasers, where employing X-ray pulses of longer durations could still provide a useful diffraction signal above the noise due to the Coulomb explosion.","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5098309","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45777561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Condensation of ground state from a supercooled phase in the Si(111)-(4 × 1) → (8 × 2)-indium atomic wire system","authors":"B. Hafke, T. Witte, D. Janoschka, P. Dreher, F. Meyer Zu Heringdorf, M. Horn-von Hoegen","doi":"10.1063/1.5111636","DOIUrl":"https://doi.org/10.1063/1.5111636","url":null,"abstract":"Strong optical irradiation of indium atomic wires on a Si(111) surface causes the nonthermal structural transition from the (8 × 2) reconstructed ground state to an excited (4 × 1) state. The immediate recovery of the system to the ground state is hindered by an energy barrier for the collective motion of the indium atoms along the reaction coordinate from the (4 × 1) to the (8 × 2) state. This metastable, supercooled state can only recover through nucleation of the ground state at defects like adsorbates or step edges. Subsequently, a recovery front propagates with constant velocity across the surface and the (8 × 2) ground state is reinstated. In a combined femtosecond electron diffraction and photoelectron emission microscopy study, we determined—based on the step morphology—a velocity of this recovery front of ∼100 m/s.","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.5111636","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41484597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Establishment of the Structural Equation of Motion","authors":"","doi":"10.1002/9781119605775.ch2","DOIUrl":"https://doi.org/10.1002/9781119605775.ch2","url":null,"abstract":"","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2019-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/9781119605775.ch2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41779399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural Dynamics of Marine Pipeline and Riser","authors":"","doi":"10.1002/9781119605775.ch8","DOIUrl":"https://doi.org/10.1002/9781119605775.ch8","url":null,"abstract":"","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2019-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/9781119605775.ch8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47395945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Index","authors":"","doi":"10.1002/9781119605775.index","DOIUrl":"https://doi.org/10.1002/9781119605775.index","url":null,"abstract":"","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2019-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/9781119605775.index","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42929805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}