1. School of Physical Sciences, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, Arkansas 72204, United States
2. Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
3. Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, Arkansas 72204, United States