Atomic physics using short-wavelength coherent radiation

Laser spectroscopy of free atoms has been pursued for 25 years starting in the visible region and with a constant thrust towards shorter wavelengths. A review of generation schemes and atomic-physics experiments in the short-wavelength region is given. Processes in ions and inner shells occur on a very fast timescale setting special demands on the sources. Using picosecond laser technology efficient frequency conversion and an adequate time resolution is achievable, but the spectral resolution is often impaired with such sources. Methods to achieve temporal as well as spectral resolution in the short-wavelength region are discussed. The use of high-order harmonics as tunable short-pulse radiation is described more in detail. Future possibilities for laser spectroscopy and atomic physics at short wavelengths are finally discussed.