Ultraschnelle Elektronenkristallographie: Anbruch einer neuen Ära

Thomas, John Meurig

doi:10.1002/ange.200301746

Cited by 6 publications

(3 citation statements)

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“…In 1991 he prophesied [7] that if the structural determination of transient chemical species, then achieved by picosecond electron diffraction on molecular beams, could be carried over to the condensed phases, it would mark the dawn of a new era. This prophecy has been fulfilled, [8,9] and the new era is admirably described by its initiator, A. H. Zewail, in his contribution. He focuses mainly on the development of the revolutionary four-dimensional electron microscopy, which is based on the premise that trajectories of coherent and timed single-electron packets can provide the equivalent image of N electrons in conventional microscopes.…”

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confidence: 96%

Physical Biology.From Atoms to Medicine. Edited by Ahmed Zewail.

Chergui

2009

Angew Chem Int Ed

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mentioning

confidence: 96%

Physical Biology.From Atoms to Medicine. Edited by Ahmed Zewail.

Chergui

2009

Angew Chem Int Ed

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“…A. H. Zewail, der Vorreiter auf diesem Gebiet, beschreibt in seinem Beitrag, wie ihm dies gelungen ist. [8,9] …”

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Physical Biology.From Atoms to Medicine. Herausgegeben von Ahmed Zewail.

Chergui

2009

Angewandte Chemie

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“…We report herein our first study on the structure and dynamics of mono‐ and bilayer phospholipids, the essential elements of biological membranes, by using ultrafast electron crystallography (UEC) 1. 2 The phospholipid was immobilized as a Langmuir–Blodgett film on hydrophilic or hydrophobic silicon substrates.…”

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confidence: 99%

Ultrafast Electron Crystallography of Phospholipids

2006

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We report herein our first study on the structure and dynamics of mono-and bilayer phospholipids, the essential elements of biological membranes, by using ultrafast electron crystallography (UEC). [1,2] The phospholipid was immobilized as a Langmuir-Blodgett film on hydrophilic or hydrophobic silicon substrates. From the diffraction patterns we determined that the dimyristoyl phosphatidic acid (DMPA; Figure 1) molecules were aligned with their aliphatic chains perpendicular to the substrate surface, and resolved the subunit cell -CH 2 -CH 2 -CH 2 -distance to be c 0 = 2.54 . After a femtosecond temperature jump in the substrate we observed, through changes in the position and intensity of the diffraction, structural dynamics on different time scales: a coherent, non-equilibrium expansion (wave-type) along the aliphatic chains on the picosecond timescale, as well as contraction and restructuring at longer times. Moreover, transient structural ordering was revealed on the ultrashort time scale. For this complex system, UEC allowed us to picture the atomic forces involved in structural dynamics at far-from-equilibrium configurations, whose collective and coherent effects may otherwise be obscured.The resemblance of both lipid Langmuir films at water surfaces and Langmuir-Blodgett (LB) films to naturally occurring biological membranes means they often serve as model systems for studying membrane structures and properties, [3,4] such as head-group organization and hydration, [5] phase transitions, [6] interactions with membrane proteins, [7,8] and proton diffusion, [9] besides other applications in molecular electronics [10] and biological sensors.[11] Studies on the structure of lipid LB films have mostly been focused on fatty acids and fatty acid salts, [12] but for phospholipids, although more complex and less studied, their structures have been probed by a variety of techniques, including electron diffraction, [13][14][15] X-ray diffraction, [5,16] infrared spectroscopy, [17,18] scanning tunneling microscopy, [19] and atomic force microscopy. [20] Structural ultrafast dynamics have not been reported. Ultrafast optical spectroscopy has been used to probe the dynamics of water solvation, [21] and inelastic neutron scattering has enabled the deduction of time scales of collective motions from the dispersion relationships.[22] UEC is well suited for the study of structural changes because of its high sensitivity, low damage at low electron flux, [23] and spatiotemporal resolutions. All experiments were carried out in our UEC apparatus, [2,24] in which the electrons are incident at a grazing angle of q i = 0-58 and are scattered by the lipid molecules to form the diffraction patterns in the far field. The scattered electrons are recorded with a low-noise, imageintensified, charge-coupled device (CCD) camera assembly capable of single-electron detection.[23]The change of the structure was initiated by a femtosecond infrared laser pulse (800 nm, 120 fs, 1 kHz repetition rate) focused onto the sample surface at an inciden...

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Ultraschnelle Elektronenkristallographie: Anbruch einer neuen Ära

Cited by 6 publications

References 33 publications

Physical Biology.From Atoms to Medicine. Edited by Ahmed Zewail.

Physical Biology.From Atoms to Medicine. Edited by Ahmed Zewail.

Physical Biology.From Atoms to Medicine. Herausgegeben von Ahmed Zewail.

Ultrafast Electron Crystallography of Phospholipids

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