Time-resolved synchrotron X-ray diffraction

Figure 22.6. (A) Temperature variation profile during, and (B) three-dimensional plots of the results obtained from, a time-resolved synchrotron X-ray diffraction experiment on SOS (1,3-distearoyl-2-oleoyl-.sn-glycerol) without annealing, a and (3 polymorphic forms LC1 liquid crystalline structure 1. (Reproduced with permission from Sato et al., 1999.)...

From the analysis of the data in the LIPID AT database (41), more than 150 different methods and method modifications have been used to collect data related to the lipid phase transitions. Almost 90% of the data is accounted for by less than 10 methods. Differential scaiming calorimetry strongly dominates the field with two thirds of all phase transition records. From the other experimental techniques, various fluorescent methods account for 10% of the information records. X-ray diffraction, nuclear magnetic resonance (NMR), Raman spectroscopy, electron spin resonance (ESR), infrared (IR) spectroscopy, and polarizing microscopy each contribute to about or less than 2-3% of the phase transition data records in the database. Especially useful in gaining insight into the mechanism and kinetics of lipid phase transitions has been time-resolved synchrotron X-ray diffraction (62,78-81). 

Fig. 1. Simultaneous DSC/WAXS/SAXS design. Experimental setup of the microcalorimeter cell in the time-resolved synchrotron X-ray diffraction environment The cell is positioned with sample-containing capillary perpendicular to the beam in such a way that the diffraction patterns are recorded in the vertical plane including the beam by one or two one-dimensional proportional detectors (Position Sensitive Linear Detector 1 and LD2). Counting Electronic (Counting Elect.), Nanovoltmeter (mVter), and Temperature Controller (T Ctrl) are all monitored by the same PC Computer (PC Comp.). Temperature-Controlled Bath (TCB) is kept at constant temperature (e.g., 20°C). Figure is adapted from Reference 3.

Coppens P, Gerlits O, Vorontsov II et al (2004) A very large Rh-Rh bond shortening on excitation of the [Rh2(l,8-diisocyano-p-menthane)4] ion by time-resolved synchrotron X-ray diffraction. Chem Comm 2144-2145... 

Joe Wong, T, Ressler and J.W. Elmer, Dynamics of phase transformations and microstructure evolution in carbon-manganese steel arc welds using time-resolved synchrotron x-ray diffraction, J. Synchrotron Rad. (2002) submitted. 

Lasocha W, Schenk H (1997) A simplified, textirre-based method for intensity determination of overlapping reflectiorts in powder diffraction. J Appl Crystallogr 30 561-564 Lee Y, Cahill C, Hanson J, Parise JB, Carr S, Myrick ML, Preckwinkel UV, Phillips JC (1999) Characterization of K -ion exchange into Na-MAX using time resolved synchrotron X-ray powder diffraction and rietveld refinement. In 12th Int l Zeolite Assoc Meeting, Baltimore, Maryland, IV 2401-2408... 

An interesting experiment of real-time growth process of LAO/STO was performed by time-resolved surface X-ray diffraction (SXRD) on the beamline 33-ID at the advanced photon source (APS) synchrotron in Argonne, showing the formation and evolution of the LAO epitaxial layers [62]. 

Microscopic time-resolved measurements of the hydrate phase during gas hydrate formation, decomposition, and inhibition began only in the mid-1990s. These techniques include in situ synchrotron x-ray diffraction (Koh et al., 1996 Klapproth et al., 2003 Uchida et al., 2003), neutron diffraction (Henning et al., 2000 Koh et al., 2000 Halpern et al., 2001 Staykova et al., 2003), Raman spectroscopy (Subramanian and Sloan, 2002 Komai et al., 2004), and NMR spectroscopy (Moudrakovski et al., 2001 Kini et al., 2004 Gupta et al., 2007). 

An interesting feature of polarized IR spectroscopy is that rapid measurements can be performed while preserving molecular information (in contrast with birefringence) and without the need for a synchrotron source (X-ray diffraction). Time-resolved IRLD studies are almost exclusively realized in transmission because of its compatibility with various types of tensile testing devices. In the simplest implementation, p- and s-polarized spectra are sequentially acquired while the sample is deformed and/or relaxing. The time resolution is generally limited to several seconds per spectrum by the acquisition time of two spectra and by the speed at which the polarizer can be rotated. Siesler et al. have used such a rheo-optical technique to study the dynamics of multiple polymers and copolymers [40]. 

Fast reactions between pure metal powders (A1 + Ni, A1 + Ti and A1 + Ni + Ti) have been studied by Javel etal. (1997) by using time-resolved X-ray diffraction with the help of synchrotron radiation. The sample (20 X 10 X 2 to 3 mm3 was prepared under purified argon by cold pressing the metal powders mixed in the required proportion. It was then placed in a reaction chamber kept under He gas. A mylar window allows the incident and diffracted X-ray beams to pass in and out. Two small heating devices (tungsten coils on alumina supports) were included. The first one was used to keep the sample at a uniform temperature before ignition and the second one to start the self-propagating reaction at one end of the sample. X-rays irradiated the centre of the specimen. 

The development of synchrotron radiation as a source for x-ray diffraction and the investigation of the structure and contractile mechanism of insect flight muscle have had a symbiotic relationship since the early 1970 s. While it is perhaps true that, until a few years ago, synchrotrcm radiation research had benefitted more from this than insect flight muscle research, recent time-resolved work has begun to fulfill the promise of those first diffraction experiments carried out by Rosenbaum et al. (1971) in 1970. 

Now I return to X-ray diffraction to describe probably the oldest type of diffraction experiment, but one whose stock has soared with the advent of synchrotron radiation and powerful computer techniques for the analysis of complex diffraction data. The method, Laue diffraction, is already realizing its promise as a means to determine the structures of short-lived reaction intermediates. This method is sometimes called time-resolved crystallography, implying an attempt to take snapshots of a chemical reaction or physical change in progress. 

Sasaki, N., Shukunami, N., Matsushima, N., and Izumi, Y. (1999). Time resolved X-ray diffraction from tendon collagen during creep using synchrotron radiation. J. Biomech. 32, 285-292. 

Huxley, H. E., Faruqi, A. R., Bordas, J., Koch, M., and Milch, J. R. (1980). The use of synchrotron radiation in time-resolved X-ray diffraction studies of myosin layer line reflections during muscle contraction. Nature 284, 140-143. 

Squire, J. M., Harford, J. J., and Al-Khayat, H. A. (1994). Synchrotron radiation in time-resolved X-ray diffraction studies of molecular movements in muscle. In Synchrotron Radiation in the Biosciences. Oxford University Press, Oxford, UK. 

Figure 17. Time-resolved synchrotron radiation X-ray diffraction patterns of concentration ratio LLL/PPP = 60/40. At left is the temperature change with time (unit nm).

Detectors used for time resolved non-crystalline diffraction experiments on a synchrotron X-ray source should have most if not all of the following characteristics ... 

An alternative track which has been pursued recently is time-resolved X-ray diffraction. An important goal is to improve the time resolution such that direct observation of the dynamics of the chemical bond is possible, corresponding to the observation of the time-dependent distribution of atomic positions. Pulsed X-rays are, e.g., obtained from synchrotron radiation or plasma sources. The temporal duration of these pulses is currently in the range of 100 ps-100 fs [4], Very recently, the first free-electron laser has produced short 100-10 fs coherent and highly intense bursts of X-rays [4—6]. 

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