[1] Agere Syst, Bell Labs, Lucent Technol, Murray Hill, NJ 07974 USA
[2] Adv Light Source, Berkeley, CA 94720 USA
[3] Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA
[4] Adv Light Source, Berkeley, CA 94720 USA
[5] Stanford Synchrotron Radiat Labs, Stanford, CA USA