Synchrotron radiation pulses

Tanaka, Y. Hara, T. Kitamura, H. Ishikawa, T. (2000). Timing Control of an Intense Picosecond Pulse Laser to the SPiing-8 Synchrotron Radiation Pulses. Reoiew of Scientific Instruments, Vol.71, No.3, (March 2000), pp. 1268-1274, ISSN 0034-6748 Tanaka, Y. Fukuyama, Y. Yasuda, N. Kim, J. Murayama, H. Kohara, S. Osawa, H. ... 

In order to monitor the real-time dynamics of gas molecules interacting with surface, time-resolved study is required. It is generally known that the time domains for the gas adsorption/desorption on surface are within pico-second regime while the molecular vibration on surface is within femto-second regime. To accommodate this time-requirement as well as chemical analysis on surface, a type of pump and probe experiment is required, which makes use of synchronization between a laser pulse and a synchrotron radiation pulse of AP-XPS endstation. For example, the carrier dynamics and reaction mechanism of photocatalysts under AP conditions can be an ideal system to look at with this time-resolved experimental set-up. At present, the synchronization technique has been well developed as shown in a block diagram (Fig. 9.24). This time-resolved set-up can be further refined and adapted into advanced system when the free electron X-ray source is available. 

F. Schotte, S. Techert, P. Anhnrud, V. Srajer, K. Moffat, and M. Wulff, Picosecond structural studies using pulsed synchrotron radiation. In D. M. Mills (ed.), Third-Generation Hard X-Ray Synchrotron Radiation Sources Source Properties, Optics, and Experimental Techniques, Chap. 10, p. 345-402. John Wiley Sons, Hobokon, NJ, 2002. 

Synchrotron radiation can also be used as an excitation source with the advantage of almost constant intensity versus wavelength over a very broad range, but the pulse width is in general of the order of hundreds of picosecond or not much less. There are only a few sources of this type in the world. 

We describe beamline ID09B at the European Synchrotron Radiation Facility (ESRF), a laboratory for optical pump and x-ray probe experiments to 100-picosecond resolution. The x-ray source is a narrow-band undulator, which can produce up to 1 x 1010 photons in one pulse. The 3% bandwidth of the undulator is sufficiently monochromatic for most diffraction experiments in liquids. A Ti sapphire femtosecond laser is used for reaction initiation. The laser mns at 896 Hz and the wavelength is tunable between 290-1160 nm. The doubled (400 nm) and tripled wavelength (267 nm) are also available. The x-ray repetition frequency from the synchrotron is reduced to 896 Hz by a chopper. The time delay can be varied from 0 ps to 1 ms, which makes it possible to follow structural processes occurring in a wide range of time scales in one experiment. 

F. Schotte, S. Techert S, P. A. Anfinrud, V. Srajer, K. Moffat and M. Wulff. Recent Advances in the Generation of Pulsed Synchrotron Radiation Suitable for Picosecond Time-resolved X-ray Studies. Third-Generation Hard X-ray Synchrotron Radiation Sources. Edited by Dennis Mills, (ISBN 0-471-31433-1). 345-401, 2002... 

Synchrotron radiation of 115 to 170 nm has been used to dissociate SiH4 in a pulsed supersonic free jet, and the abundance of SiH2 was measured by quadrupole mass spectrometry using 11 V sub-ionization threshold electron-impact energy301. The possible detection of SiH2 in the outer envelope of a stellar object has been reported302. 

Very recently. LET effects on fluorescence lifetimes of low molecular polyethylene model compounds (n-alkane) have been studied by many kinds of pulse radiolysis - methods such as electron beam, ion beam and synchrotron radiation (SR) [40] pulse radiolysis techniques [41]. Figure 10 shows time profiles of the fluorescence from neat n-dodecane liquids irradiated many kinds of radiation with different LET. The fluorescence lifetimes from irradiated neat... 

Fig. 10. Decay curves observed in electron beam, synchrotron radiation (SR), and ion beam pulse radiolysis of neat n-dodecane liquids...

One kind of X-ray lasers is a subcase of the so-called free electron laser. Electrons, accelerated are forced, to almost the speed of light ("relativistic electrons") by klystrons and then bent or wiggled in special magnets called undulators are forced to emit some of their energy as synchrotron radiation inside the undulator, the synchrotron pulses can induce in-phase synchrotron emission by other electrons, thus producing a pulse at X-ray wavelengths. This was recently demonstrated as almost possible (2009). 

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.)... 

Most recently, the range of asymmetric photochemistry was extended to shorter wavelengths by the use of synchrotron radiation and two-photon excitation. New developments are visible with high-intensity and ultrashort pulse lasers (see Sec. D of this chapter and Chap. 2 of this book). 

David WIF (1987) The scope and possibilities of crystallography with pulsed neutrons. In Carrondo MA, Jeffrey GA (eds) Chemical crystallography with pulsed neutrons and synchrotron radiation. NATO ASI, C221, Reidel, Dordrecht, pp 27-57... 

The types of radiations that are used in structural crystallography are mainly x-rays, neutrons, and electrons. The use of electrons is still difficult for structure determination but can be a useful tool for the detection of structural transitions (see Section X). White or monochromatic x-ray beams can conveniently be obtained from sealed tubes, rotating anode generators, or synchrotron sources [5], with relative flux magnitudes on the order of 1, 10, >100, respectively. The first two x-ray sources are continuous and are generally designed to produce almost monochromatic beams, while synchrotron radiation is pulsed and white. Neutron sources are comparatively much weaker and are either continuous (nuclear reactor) or pulsed (spallation source [6]). 

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