USE OF LEAD-GLASS CAPILLARIES FOR MICRO-FOCUSING OF HIGHLY-ENERGETIC (O-60 KEV) SYNCHROTRON-RADIATION

The performance of ellipsoidally shaped lead-glass capillaries for foc using the polychromatic synchrotron beam produced by a bending magnet of the DORIS positron storage ring (Hasylab, Hamburg, Germany) is disc ussed. The size, intensity and energy distribution of the focused beam produced by such capillaries are compared with those of beams generat ed by means of straight borosilicate capillaries, indicating that beam sizes of ca, 4 mu m at the sample surface can be obtained with a tota l flux density that is ca. ten times higher than when a collimated bea m is employed, Synchrotron radiation with energies up to 60 keV is foc used, leaving the original energy distribution of the white synchrotro n beam virtually unchanged. The analytical characteristics of the mu-X RF set-up at Beamline L of Hasylab, when equipped with a lead-glass ca pillary, were investigated by means of NIST SRMs and indicate that int erference-free absolute/relative detection limits in the 1-10 fg/0.8-2 ppm range are achievable from 100 mu m silicate-type samples for the elements from Mn (Z=25) to Gd (Z=64) using their K alpha lines within 1000 s counting time. Elemental yields are situated in the 10-100 coun ts s(-1) per 100 mA per (mu g cm(-2)) range. As illustrations of the t ype of investigations these highly energetic, micrometre-sized beams m ake possible, the two-dimensional mapping of the distribution of REEs (rare earth elements) and other heavy elements in geological igneous r ock samples and the three-dimensional non-destructive analysis of heav y metals (such as V, Fe, Ni and Mo) in individual fly-ash particles by means of fluorescence microtomography are briefly described.