[1] Georgetown Univ, Dept Phys, Washington, DC 20057 USA
[2] Georgetown Univ, Inst Soft Matter Synth & Metrol, Washington, DC 20057 USA
[3] CUNY City Coll, Benjamin Levich Inst, New York, NY 10031 USA
[4] CUNY City Coll, Dept Chem Engn, New York, NY 10031 USA