10.1021/acs.jpclett.5b01835.s001
Jason
K. Streit
Jason
K.
Streit
Sergei M. Bachilo
Sergei M.
Bachilo
Stephen R. Sanchez
Stephen R.
Sanchez
Ching-Wei Lin
Ching-Wei
Lin
R. Bruce Weisman
R. Bruce
Weisman
Variance Spectroscopy
American Chemical Society
2015
bulk spectroscopy
emissive efficiencies
particle aggregation
Variance spectroscopy
Variance SpectroscopySpectroscopic analysis
intensity variations
nanoparticle studies
covariance maps
nanoparticle samples
nanotube
Covariance analysis
fluorescence spectra
2015-12-17 09:52:14
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Variance_Spectroscopy/2054259
Spectroscopic
analysis and study of nanoparticle samples is often
hampered by structural diversity that presents a complex superposition
of spectral signatures. By probing the spectra of small volumes within
dilute samples, we can expose statistical variations in composition
to obtain information unavailable from bulk spectroscopy. This new
approach is demonstrated using fluorescence spectra of unsorted single-walled
carbon nanotube samples to deduce structure-specific abundances and
emissive efficiencies. Furthermore, correlations between intensity
variations at different wavelengths provide two-dimensional covariance
maps that isolate the spectra of homogeneous subpopulations. Covariance
analysis is also a sensitive probe of particle aggregation. It shows
that well-dispersed nanotube samples can spontaneously form loose
aggregates of a type not previously recognized. Variance spectroscopy
is a simple and practical technique that should find application in
many nanoparticle studies.