[1] Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA
[2] SLAC Natl Accelerator Lab, Stanford PULSE Inst, Menlo Pk, CA 94025 USA
[3] SLAC Natl Accelerator Lab, Linac Coherent Light Source, Menlo Pk, CA 94025 USA
[4] Univ Calif Davis, Dept Chem, Davis, CA 95616 USA
[5] Stanford Univ, Dept Phys, Stanford, CA 94305 USA
[6] Lawrence Berkeley Natl Lab, Chem Sci Div, Berkeley, CA 94720 USA