Ultrafast Time-Resolved Transient Structures of Solids and Liquids Studied by Means of X-ray Diffraction and EXAFS

Abstract

Picosecond and nanosecond transient structures have been observed directly using time-resolved X-ray diffraction and absorption. These experiments provide insight on the evolution of transient molecular structure on the atomic length scale during the course of a chemical reaction. Recent advances in the generation of short X-ray pulses and detectors have made time-resolved X-ray studies a reality. We discuss a few of the vast number of possible time-resolved structure studies in solids and fluids. Ultrafast relaxation dynamics of crystal lattice structures induced by picosecond and nanosecond laser pulses have been observed by means of time-resolved picosecond and nanosecond X-ray diffraction. Lattice deformation with 10 ps and 10 -3 Å resolution have been performed. The picosecond X-ray system, which we have used, is described, and its application to time-resolved ultrafast X-ray diffraction in crystals and EXAFS in liquids is discussed.

Synchrotron ultrafast techniques for photoactive transition metal complexes

“…(d) Ultrafast X-ray absorption spectroscopy: challenges and possibilities Ultrafast laser pump X-ray probe XAS experiments have been proposed since the end of the 1990s [135][136][137][138]. Initially, the time resolution of these studies was limited to the ms-ns range [139][140][141][142], except for one groundbreaking case [143].Theoretical and experimental critical issues had to be considered to extend the feasibility of time-resolved XAS characterization to the sub-ns time domain.…”

Proposal to DOE Basic Energy Sciences: Ultrafast X-ray science facility at the Advanced Light Source

“…X-rays are ideal probes of atomic structure because they interact with core electronic levels that are closely bound to the atomic nucleus. A growing number of research groups around the world are applying ultrafast x-ray techniques to investigate structural dynamics in a variety of condensed matter systems [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], however, future progress in this field is substantially limited at present due to the lack of suitable short-pulse x-ray sources.…”

“…Laser driven x-ray diodes (essentially x-ray tubes with photocathodes illuminated by femtosecond laser pulses) are also being developed for time-resolved x-ray research [7]. The properties of these sources are similar to the laser-plasma sources in that x-rays are emitted in 4π, and the spectrum consists of line emission superimposed on a continuum background.…”

“…However, the x-ray flux is determined by the charge in the electron pulse, which is limited by space-charge effects. Spacecharge effects also limit the achievable electron pulse duration, which is typically in the picosecond range [7].…”

Structures of bromoalkanes' photodissociation in solution by means of ultrafast extended x-ray absorption fine-structure spectroscopy

“…Most of these techniques use an ultrashort laser pulse to initiate the photoreaction in the sample studied followed by a delayed ultrashort electron or x-ray pulse that probes the changes that take place in the sample. In the solid state, laser-induced heat and strain propagation in metal and semiconductor single and mosaic crystals has been studied by means of nanosecond and picosecond time-resolved x-ray diffraction (2)(3)(4)(5)(6)(7)(8). Reflective low and high energy electron diffraction techniques have also been used to study laser-induced surface melting and crystal lattice thermal relaxation with nanosecond and picosecond time resolution (9)(10)(11)(12).…”