2008 Volume 77 Issue 2 Pages 136-142
High-density plasma created near a solid surface by an intense femtosecond laser pulse emits ultrashort X-ray pulses that are synchronized with the laser pulse. It is expected that the ultrafast response of optically excited materials will be observed by employing X-rays from femtosecond-laser-produced plasmas in the pump-probe scheme. With this in mind, efforts have been made to demonstrate time-resolved diffraction and absorption measurements. We can extract microscopic information on materials, such as the electronic states of the atoms, chemical bonds, and local structures, from an X-ray absorption spectrum. Therefore, by employing short X-ray pulses to measure the X-ray absorption of optically excited materials, we can expect to directly probe such transition states as structural and phase changes induced by the laser field. In this paper, we will describe examples of time-resolved soft X-ray absorption spectroscopy using a femtosecond laser-produced plasma soft X-ray pulse as a dynamic probe.
