(19)

(11)

EP 1 018 138 A1

(12)

(43) Date of publication: 12.07.2000 Bulletin 2000/28 (21) Application number: 98953178.5 (22) Date of filing: 22.09.1998

(51) International Patent Classification (IPC)7: H01J 37/20, G01B 7/34 (86) International application number: PCT/US9819/764 (87) International publication number: WO 9916/102 (01.04.1999 Gazette 1999/13)

(84) Designated Contracting States: AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE (30) Priority: 22.09.1997 US 59471 P (71) Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA Oakland, CA 94612-3550 (US)	(72) Inventors: XIANG, Xiao-Dong Alameda, CA 94502 (US) GAO, Chen Alameda, CA 94501 (US) (74) Representative: Cross, Rupert Edward Blount et al BOULT WADE TENNANT,Verulam Gardens70 Gray's Inn Road London WC1X 8BT London WC1X 8BT (GB)