Recently there has been incredible effort geared towards the development of a coherent x-ray source, which may be readily usable for numerous applications such as high-resolution biological imaging, medical applications and generation of ultra high energy radiations. Nowadays, several coherent soft x-ray sources have been reported. Numerous methods have been employed to generate this radiation including high-order harmonic generation, discharge-pumped soft x-ray lasers, free-electron lasers and Thompson scattering sources. However, none of these sources has proven capable of generating kilovolt radiation with a high brightness level.

An extremely effective method of generating this coherent radiation would be to create a controlled population inversion in the inner shells of high-Z atoms. If the majority of the atoms in an ensemble have the inverted electron configuration, then this is referred to as a population inversion. To this end, a large body of experimental work has been performed in the generation if inner-shell hollow atom spectra, in attempts to construct a coherent source of this type.

In our laboratory we study coherent x-ray radiation generating hollow atom L-shell and M-shell spectra from xenon clusters using a sub-picosecond laser source. In our case the rare gas clusters excited by ultra-intense (~ 10^19 W/cm2) ultraviolet laser radiation.

The generated coherent powerful x-ray radiation have been used for:
(a) biological microimaging at the molecular level (a program of activity aimed at the mechanisms underlining cell cycle control and apoptosis),
(b) x-ray lithography, and
(c) the use of cryptography for the organization of both physical particle mass states and bioinformatics data pertaining to protein structures and information.

We are planning to use the beam for other applications as well.