[1] Sandia Natl Labs, Albuquerque, NM 87185 USA
[2] Univ New Mexico, Dept Nucl Med, Albuquerque, NM 87131 USA
[3] Northwestern Univ, Dept Chem, Evanston, IL USA
[4] Northwestern Univ, Dept Mat Sci & Engn, Evanston, IL 60208 USA
[5] Northwestern Univ, Dept Elect & Comp Engn, Evanston, IL USA
[6] Sandia Natl Labs, Ctr Integrated Nanotechnol CINT, Albuquerque, NM 87123 USA