B. Hafke, T. Witte, D. Janoschka, P. Dreher, F. Meyer Zu Heringdorf, M. Horn-von Hoegen
{"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":"E. coli DHFR complex with a reaction intermediate","authors":"H. Cao, J. Skolnick","doi":"10.2210/PDB6MR9/PDB","DOIUrl":"https://doi.org/10.2210/PDB6MR9/PDB","url":null,"abstract":"Time-resolved crystallography is a powerful technique to elucidate molecular mechanisms at both spatial (angstroms) and temporal (picoseconds to seconds) resolutions. We recently discovered an unusually slow reaction at room temperature that occurs on the order of days: the in crystalline reverse oxidative decay of the chemically labile (6S)-5,6,7,8-tetrahydrofolate in complex with its producing enzyme Escherichia coli dihydrofolate reductase. Here, we report the critical analysis of a representative dataset at an intermediate reaction time point. A quinonoid-like intermediate state lying between tetrahydrofolate and dihydrofolate features a near coplanar geometry of the bicyclic pterin moiety, and a tetrahedral sp3 C6 geometry is proposed based on the apparent mFo-DFc omit electron densities of the ligand. The presence of this intermediate is strongly supported by Bayesian difference refinement. Isomorphous Fo-Fo difference map and multi-state refinement analyses suggest the presence of end-state ligand populations as well, although the putative intermediate state is likely the most populated. A similar quinonoid intermediate previously proposed to transiently exist during the oxidation of tetrahydrofolate was confirmed by polarography and UV-vis spectroscopy to be relatively stable in the oxidation of its close analog tetrahydropterin. We postulate that the constraints on the ligand imposed by the interactions with the protein environment might be the origin of the slow reaction observed by time-resolved crystallography.","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":"6 1","pages":"024701-024701"},"PeriodicalIF":2.8,"publicationDate":"2019-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43526956","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}
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