[1] Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA
[2] Stanford Univ, Dept Chem Engn, Stanford, CA 94305 USA
[3] Stanford Univ, Dept Chem, Stanford, CA 94305 USA
[4] KTH Royal Inst Technol, S-10044 Stockholm, Sweden
[5] Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA
[6] SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA