Anomalous Dispersion of Longitudinal Optical Phonons inNd1.86Ce0.14CuO4+δDetermined by Inelastic X-Ray Scattering

Inelastic x-ray scattering (IXS) with very high (meV) energy resolution has become a valuable spectroscopic tool, complementing the well established coherent inelastic neutron scattering (INS) technique for phonon dispersion investigations. In the study of crystalline systems IXS is a viable alternative to INS, especially in cases where only small samples are available. Using IXS, we have measured the phonon dispersion of Nd1.86Ce0.14CuO4 + δ along the [ξ, 0, 0] and [ξ, ξ, 0] in-plane directions. Compared to the undoped parent compound, the two highest longitudinal optical (LO) phonon branches are shifted to lower energies because of Coulomb-screening effects brought about by the doped charge carriers. An additional anomalous softening of the highest branch is observed around q = (0.2, 0, 0). This anomalous softening, akin to what has been observed in other compounds, provides evidence for a strong electron-phonon coupling in the electron-doped high-temperature superconductors.

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Inelastic x-ray scattering study of superconductingSmFeAsO1−xFysingle crystals: Evidence for strong momentum-dependent doping-induced renormalizations of optical phonons

Physical Review B ◽

10.1103/physrevb.80.220504 ◽

2009 ◽

Vol 80 (22) ◽

Cited By ~ 26

Author(s):

M. Le Tacon ◽

T. R. Forrest ◽

Ch. Rüegg ◽

A. Bosak ◽

A. C. Walters ◽

...

Keyword(s):

Optical Phonons ◽

X Ray ◽

X Ray Scattering ◽

Scattering Study ◽

Ray Scattering

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Overbending of the longitudinal optical phonon branch in diamond as evidenced by inelastic neutron and x-ray scattering

Physical Review B ◽

10.1103/physrevb.66.241202 ◽

2002 ◽

Vol 66 (24) ◽

Cited By ~ 32

Author(s):

J. Kulda ◽

H. Kainzmaier ◽

D. Strauch ◽

B. Dorner ◽

M. Lorenzen ◽

...

Keyword(s):

Optical Phonon ◽

Longitudinal Optical ◽

Inelastic Neutron ◽

Longitudinal Optical Phonon ◽

Phonon Branch ◽

X Ray ◽

X Ray Scattering ◽

Optical Phonon Branch ◽

Ray Scattering

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Theory of X-ray scattering in the anomalous dispersion region and the problem of atomic-ternary-correlation-function determination in amorphous media

Journal of Physics Condensed Matter ◽

10.1088/0953-8984/4/28/016 ◽

1992 ◽

Vol 4 (28) ◽

pp. 6155-6169 ◽

Cited By ~ 13

Author(s):

R V Vedrinskii ◽

V L Kraizman ◽

A A Novakovich ◽

V Sh Machavariani

Keyword(s):

Correlation Function ◽

Anomalous Dispersion ◽

X Ray ◽

Dispersion Region ◽

X Ray Scattering ◽

Amorphous Media ◽

Ray Scattering

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Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077402 ◽

1983 ◽

Vol 41 ◽

pp. 766-767

Author(s):

Eva-Maria Mandelkow ◽

Eckhard Mandelkow ◽

Joan Bordas

Keyword(s):

Electron Microscopy ◽

Dynamic Equilibrium ◽

Time Resolved ◽

X Ray ◽

Additional Information ◽

X Ray Scattering ◽

Low Concentrations ◽

Microtubule Growth ◽

Ray Patterns ◽

Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

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Time-Resolved Cryo-Electron Microscopy of Oscillating Microtubules

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100181269 ◽

1990 ◽

Vol 48 (1) ◽

pp. 502-503

Author(s):

Eva-Maria Mandelkow ◽

Ron Milligan

Keyword(s):

Electron Microscopy ◽

Dynamic Instability ◽

Entire Solution ◽

Reaction Scheme ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

A Chain ◽

Ray Scattering

Microtubules form part of the cytoskeleton of eukaryotic cells. They are hollow libers of about 25 nm diameter made up of 13 protofilaments, each of which consists of a chain of heterodimers of α-and β-tubulin. Microtubules can be assembled in vitro at 37°C in the presence of GTP which is hydrolyzed during the reaction, and they are disassembled at 4°C. In contrast to most other polymers microtubules show the behavior of “dynamic instability”, i.e. they can switch between phases of growth and phases of shrinkage, even at an overall steady state [1]. In certain conditions an entire solution can be synchronized, leading to autonomous oscillations in the degree of assembly which can be observed by X-ray scattering (Fig. 1), light scattering, or electron microscopy [2-5]. In addition such solutions are capable of generating spontaneous spatial patterns [6].In an earlier study we have analyzed the structure of microtubules and their cold-induced disassembly by cryo-EM [7]. One result was that disassembly takes place by loss of protofilament fragments (tubulin oligomers) which fray apart at the microtubule ends. We also looked at microtubule oscillations by time-resolved X-ray scattering and proposed a reaction scheme [4] which involves a cyclic interconversion of tubulin, microtubules, and oligomers (Fig. 2). The present study was undertaken to answer two questions: (a) What is the nature of the oscillations as seen by time-resolved cryo-EM? (b) Do microtubules disassemble by fraying protofilament fragments during oscillations at 37°C?

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