Femtosecond Molecular Dynamics in the Liquid Phase Studied by Time-Resolved CARS

Author(s):  
H. Okamoto ◽  
R. Inaba ◽  
K. Yoshihara ◽  
M. Tasumi
Author(s):  
Yurema Teijeiro-Gonzalez ◽  
Alessandro Crnjar ◽  
Andrew J. Beavil ◽  
Rebecca L. Beavil ◽  
Jakub Nedbal ◽  
...  

2006 ◽  
Vol 59 (2) ◽  
pp. 81 ◽  
Author(s):  
Ales Charvat ◽  
Andreas Bógehold ◽  
Bernd Abel

Liquid water beam desorption mass spectrometry is an intriguing technique to isolate charged molecular aggregates directly from the liquid phase and to analyze them employing sensitive mass spectrometry. The liquid phase in this approach consists of a 10 µm diameter free liquid filament in vacuum which is irradiated by a focussed infrared laser pulse resonant with the OH-stretch vibration of bulk water. Depending upon the laser wavelength, charged (e.g. protonated) macromolecules are isolated from solution through a still poorly characterized mechanism. After the gentle liquid-to-vacuum transfer the low-charge-state aggregates are analyzed using time-of-flight mass spectrometry. A recent variant of the technique uses high performance liquid chromatography valves for local liquid injections of samples in the liquid carrier beam, which enables very low sample consumption and high speed sample analysis. In this review we summarize recent work to characterize the ‘desorption’ or ion isolation mechanism in this type of experiment. A decisive and interesting feature of micro liquid beam desorption mass spectrometry is that — under certain conditions — the gas-phase mass signal for a large number of small as well as supramolecular systems displays a surprisingly linear response on the solution concentration over many orders of magnitude, even for mixtures and complex body fluids. This feature and the all-liquid state nature of the technique makes this technique a solution-type spectroscopy that enables real kinetic studies involving (bio)polymers in solution without the need for internal standards. Two applications of the technique monitoring enzyme digestion of proteins and protein aggregation of an amyloid model system are highlighted, both displaying its potential for monitoring biokinetics in solution.


2018 ◽  
Vol 60 (5) ◽  
pp. 846
Author(s):  
Г.М. Полетаев ◽  
Д.В. Новоселова ◽  
И.В. Зоря ◽  
М.Д. Старостенков

AbstractThe formation of an excess free volume in triple junctions during crystallization has been studied by the molecular dynamics model using nickel as an example. It is shown that an excess free volume that forms during nickel crystallization in triple junctions predominantly forms as a result of the fixation of the liquid phase volume when contacting three crystallization fronts that contains, after crystallization, a high fraction of the free volume. In some cases, as the free volume is concentrated in triple junctions, a comparatively small crystalline subgrain (from one to several nanometers in diameter) forms, and the subgrain has the orientation different from those of contacting grains and exists in the extended state.


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