Search for "frequency characterization" in Full Text gives 2 result(s) in Beilstein Journal of Nanotechnology.
Beilstein J. Nanotechnol. 2014, 5, 964–972, doi:10.3762/bjnano.5.110
Beilstein J. Nanotechnol. 2012, 3, 294–300, doi:10.3762/bjnano.3.33