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Ionization balance of l0ps KrF laser produced plasmas was investigated under various irradiation conditions. From the laser intensity dependence of relative conversion efficiencies of emissions from F-like and Ne-like Ge ions, it was found that higher ionization state was realized, when a prepulse ASE(amplified spontaneous emission) accompanying a l0ps pulse was suppressed. The absolute conversion efficiency of X-rays from 6A to 9A was also estimated.

Reported is a search for the x‐ray amplification in a recombining fluorine plasma produced by the irradiation of a 10 ps KrF laser pulse. The pulse energy was 1 J and the maximum line‐focus length was 1 mm with 20 μm width. Fluorine Hα (81 A) intensity at 50 μm showed exponential growth of gl≊2, and gl≊1.5 for 11s2P‐1s3d line (103.8 A) at 100 μm. From the spatial distributions of He‐like and Li‐like ions, we discuss the detail of the plasma produced.

Resonantly photo‐excited Al He α (7.76 A) fluorescence is observed in the configuration where the photo‐excited Al plasma expanded parallel to the blow off direction of the other Al plasma as a flash lamp. Both plasmas are produced by the irradiation of 10 ns KrF laser pulses on an Al slab target with a step‐height of around 500 μm. Doppler de‐coupling between two plasmas caused by the steep velocity gradient in expanding plasmas is reduced in this configuration. From the spatial distribution of the fluorescence, the scale length of velocity gradient is evaluated.

Soft X-ray contact microscopy has been performed using a short-lived laser-produced plasma as the X-ray source. Single-shot exposures have been recorded in X-ray photoresists, for both dried and in vivo conditions using the high-power Nd : glass and KrF excimer laser systems, available at the SERC Central Laser Facility. The short exposure times of 1 ns and 30 ns respectively allow latent images of the specimens to be recorded before the onset of radiation damage.

The feasibility of using high-power pulsed lasers (several tens of joules per pulse) to produce plasmas as soft X-ray sources for contact microscopy is discussed and demonstrated for a wide range of biological and other material. As in other forms of X-ray microscopy, complicated and probably artefact-inducing specimen preparation is not necessary. The short pulse lengths of the lasers mean that, for single shot exposures, images can be obtained before radiation damage has altered the structure of the specimen, and this higher resolutions are possible, in principle, than for other forms of X-ray microscopy.

The development of plasma sources of soft x‐rays, using pulsed KrF (600mJ) and Nd:YAG (500mJ) lasers, is described. The intensities and spectral properties of the sources have been investigated for various target materials. The use of the sources in soft x‐ray contact microscopy will be described.