The realization of sub-nanosecond pump and probe experiments at the ESRF. European Synchrotron Radiation Facility.
We present beamline ID09B that is designed for pump and probe experiments to 50 ps time-resolution. The beamline has been refurbished with a narrow-bandwidth undulator for Laue diffraction and diffraction from liquids. The new undulator has 235 poles, a 17 mm magnetic period and is operated at 6.5 mm gap. It produces a spectral flux of 2.0 x 10(8) photon/0.1% bw/pulse (10 mA) at the fundamental at 15.5 keV and an integral flux of 1.1 x 10(10) photon pulse(-1) in a 2.5% bandwidth. The optics has been renewed with a high-precision toroidal mirror and a cryogenic monochromator. The X-ray chopper used for single pulse selection is also described together with the femtosecond laser. Finally the diffraction from excited iodine molecules in CCl4 is investigated on the nanosecond time-scale. It turns out that the high-angle scattering is insensitive to the thermal chock from the laser: these oscillations are therefore readily used for structure determination. Conversely, the low-angle scattering probes the hydrodynamics of the liquid over longer length scales and the oscillations are believed to originate from thermal stress and expansion of the solvent.
Wullf
Michael
M
European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, Grenoble Cedex 38043, France.
Plech
Anton
A
Eybert
Laurent
L
Randler
Rudolf
R
Schotte
Friedrich
F
Anfinrud
Philip
P