[1] Univ Delhi, Deshbandhu Coll, Dept Phys, New Delhi 110019, India
[2] Univ Missouri, Dept Chem & Biochem, St Louis, MO 63121 USA
[3] Univ Missouri, Dept Phys & Astron, St Louis, MO 63121 USA
[4] Ohio State Univ, Visual & Biomed Opt Lab, Columbus, OH 43212 USA
[5] Florida Int Univ, Biomol Sci Inst, Miami, FL 33199 USA