AN HARD X-RAY WAVEGUIDE FOR SUBMICROMETER COHERENT BEAM PRODUCTION. S. Lagomarsino^#, W. Jark^$, S. Di Fonzo^$, A. Cedola^#*, C. Riekel^*. ^#Istit. Elettronica Stato Solido - CNR, Rome, Italy; ^$Sincrotrone Trieste, Padriciano, Trieste, Italy; ^*ESRF- Grenoble, France

A submicrometer line-focus beam with one dimension down to 150 nm has been obtained with a hard x-ray waveguide based on a resonance effect in thin films. Only for well determined incidence angles corresponding to different resonance orders the waveguide allows an enhancement of the e.m. field inside the thin film and a propagating resonant beam. A flux of 108 ph/s from the waveguide has been measured with an incident monochromatic beam of 13 KeV from BL1 of ESRF. The transverse dimension of the beam has been measured by means of a test lithographic pattern, yielding an effective beam dimension of 400 nm at about 0.1 mm from the waveguide. Considering the divergence of the beam this corresponds to about 150 nm at the waveguide exit. The spatial intensity distribution of the beam exiting from the waveguide has been measured in the far field by means of a pin-diode detector with an angular acceptance of 0.55 mrad. The Fraunhofer diffraction pattern for the different resonance orders has been measured and fitted by considering two coherent beams exiting from the waveguide with an angular aperture between them of twice the internal reflecting angle.

Considerable flux enhancement (5x109 ph/s/0.1 Å) has been obtained by using a multilayer beam with a bandpass of 10-2 at 15 KeV. In practice the whole energy range is transmitted through the waveguide. Test diffraction patterns of Al₂O₃ and polyethilene have been obtained with the submicrometer beam.