[1] Univ Calif Berkeley, Chem & Biomol Engn, Berkeley, CA 94720 USA
[2] Univ Calif Berkeley, Vis Sci Grp, Berkeley, CA 94720 USA
[3] Stanford Univ, Chem Engn, Stanford, CA 94305 USA
[4] SLAC Natl Accelerator Lab, Stanford Synchrotron Radiat Light Source, Menlo Pk, CA USA