[1] UNIV PARIS 11, F-91405 ORSAY, FRANCE
[2] UNIV PARIS 06, F-75230 PARIS 05, FRANCE
[3] CENS, F-91190 GIF SUR YVETTE, FRANCE
[4] IBM CORP, THOMAS J WATSON RES CTR, YORKTOWN HTS, NY 10598 USA
[5] LAB UTILISAT RAYONNEMENT ELECTROMAGNET, ORSAY, FRANCE
[6] CTR NATL RECH SCI, GRENOBLE, FRANCE