Nanosecond time resolution

Kummer S, Mais S and Basche T 1995 Measurement of optical dephasing of a single terrylene molecule with nanosecond time resolution J. Chem. Phys. 99 17 078-81... 

With nanosecond time resolution, sensitive, accurate detectors, studies of these release waves have proven to be particularly revealing. First-order descriptions of release properties were obtained with rudimentary instrumentation from the earliest studies [65A01] it has required the most sophisticated modern instrumentation to provide the necessary detail to obtain a clear picture of the events. Characteristically different profiles are encountered in the strong-shock, elastic, and elastic-plastic regimes. 

The development of devices that provide a direct measure of stress or particle velocity led to observations of new rate-dependent mechanical responses and showed the power of such time-resolved measurements. The quartz gauge was the first of these devices with nanosecond time resolution, but its upper operating limit of 4 GPa limited its application. The development of the VISAR has had the most substantial impact on capabilities. VISAR systems, with time-resolution approaching 1 ns and the ability to work to pressures of 100 GPa, provide capabilities that have substantially altered the scientific descriptions of shock-compressed matter. 

The formation of 7a was also observed in solution using laser flash photolysis (LFP) with nanosecond time resolution.25,26 In Freon-113 7a shows an absorption maximum at 470 nm, and a life-time of longer than 20 xs.25 The rate of 2.9 x 109 M 1 s-1 for this reaction is almost the diffusion limit and implies a very small or absent barrier. In aqueous solution the rate constant for the reaction of la with 3Oj is 3.5 x 109 M-1 s-1, and the absorption maximum of 7a was determined as 460 nm.26 This clearly demonstrates that the oxidation of carbene la in solid argon and in solution follows the same reaction pathway. 

Analysis of rotational mobility of fluorophores by observation of fluorescence depolarization with nanosecond time resolution(28) or by variation of the lifetime (by the action of quenchers ).(9,29 30)... 

The elucidation of the intramolecular dynamics of tryptophan residues became possible due to anisotropy studies with nanosecond time resolution. Two approaches have been taken direct observation of the anisotropy kinetics on the nanosecond time scale using time-resolved(28) or frequency-domain fluorometry, and studies of steady-state anisotropy for xFvarying within wide ranges (lifetime-resolved anisotropy). The latter approach involves the application of collisional quenchers, oxygen(29,71) or acrylamide.(30) The shortening of xF by the quencher decreases the mean time available for rotations of aromatic groups prior to emission. 

With nanosecond time resolution, it was not possible to determine... 

Fluang X, Powell J, Mooney LA, Li C, Frenkel K (2001) Importance of complete DNA digestion in minimizing variability of 8-oxo-dG analyses. Free Rad Biol Med 31 1341-1351 Janata E (1982) Pulse radiolysis conductivity measurements in aqueous solutions with nanosecond time resolution. Radiat Phys Chem 19 17-21... 

Fig. 28 Schematic view of the Zeiss Plate Vision instrument which is state-of-the art for ultra-high throughput screening (uHTS) for drug discovery. The instrument resembles a 96-well parallel microscope the light of a excitation source (Xe-lamp or pulsed laser) is expanded to illuminate a microtiter plate. The excitation is structured into 96 channels by a mini-lens array (MLA) and focused into the well with a detection volume of < 100 nL. All 96 channels are read simultaneously by a gated, intensifed CCD. With this fast detector and the pulsed laser excitation, the instrument can be used to carry out miniaturized, 96 parallel lifetime measurements in microtiter plate format with nanosecond time resolution or time-gated detection [190]...

The conventional flash photolysis setup to study photochemical reactions was drastically improved with the introduction of the pulsed laser in 1970 [17], Soon, nanosecond time resolution was achieved [13], However, the possibility to study processes faster than diffusion, happening in less than 10 10 s, was only attainable with picosecond spectroscopy. This technique has been applied since the 1980s as a routine method. There are reviews covering the special aspects of interest of their authors on this topic by Rentzepis [14a], Mataga [14b], Scaiano [18], and Peters [14c],... 

Traditionally, x-ray spectroscopy measures an inhomogeneous distribution of structures, represented by the nuclear Debye Waller factors, and yields no information on the time scales of their rearrangements. Collective protein motions after fast optical triggers, on the other hand, have been studied with the help of pulsed synchrotron radiation with nanosecond time resolution (11). (See also Ref. 12 for a collection of review articles on time-resolved diffraction techniques.)... 

Since the radiation chemistry of water and aqueous solutions is well understood and the yields of the primary species are well characterised, the radiolysis of aqueous solutions has become perhaps the most versatile means of studying a wide range of free radical and redox processes in solution, especially when combined with the nanosecond time-resolution which is routinely available with pulse radiolysis. It is outside the scope of this review to consider the wide range of processes which have been studied using these techniques and the reader is referred to the paper by Buxton(68) for further information. 

Other techniques have been used for getting sub-nanosecond time resolution. These include the fast conductivity experiments of the electron in non-polar media. Streak camera detection has been used for the measurement of fluorescence from scintillators in hydrocarbon solutions. These experiments probe the role of the transfer of energy from solvent excited states to scintillators in comparison with the role of ion-recombination to form the scintillator excited states. ... 

Janata E. (1982) Pulse radiolysis conductivity measirrements in aqueous solutions with nanosecond time resolution. Radiat Phys Chem 19 17-21. 

In later PR-TRMC measurements, the after-pulse relaxation of the microwave conductivity itself in pure gases was monitored with nanosecond time-resolution and this provided a more detailed, quantitative method of monitoring electron thermalization. Of particular importance was a detailed study of thermalization in helium, which could be used to test the predictions of different theoretical treatments for this well-characterized gas. Detailed thermalization data were also obtained for oxygen, for which the concurrent three-body attachment process provides an interesting complication. The dramatic influence of small concentrations of water vapor on the thermalization process was also demonstrated for samples of dry and humid air. ° The (unexpectedly) high thermalization... 

On the basis of studies using nanosecond time resolution, Holcman and Sehested suggested that the reaction of hydroxyl radicals with dimethylaniline occurs via the intermediate formation of a hydroxyl radical-amine adduct [100], as described in Scheme 8. 

Zachariasse, K. A., Kuehnle, W., Leinhos, U., Reynders, P., Striker, G., Time resolved Monomer and Excimer Fluorescence of 1,3 Di(l pyrenyl)propane at Different Temperatures No Evidence for Distributions from Picosecond Laser Experiments with Nanosecond Time Resolution, J. Phys. Chem. 1991, 95, 5476 5488. 

To collect this volume of data, linear accelerators with nanosecond time resolution were, and still are now, routinely used around the world. Faster, picoseond linac machines were built first in Toronto and then at Argonne National Laboratory. Picosecond accelerators for pulse radiolysis have been in use for nearly three decades at Argonne, at the Osaka University Radiation Laboratory, and the University of Tokyo Nuclear Engineering Research... 

As in liquid scintillator, position reconstruction can be used to define a containment volume for the spatial coincidence between the positron and neutron. A position for each event can be reconstructed using the difference in photon arrival times among struck phototubes. The SuperKamiokande detector, similar in size to the detector considered here, has a vertex resolution of about 0.5 m in each Cartesian coordinate for 7 MeV electrons, with about 7 struck phototubes per MeV. The resolution is fixed by the number of struck phototubes, by the geometry and by the few nanosecond timing resolution of the phototubes. 

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