1 research outputs found
Single-Shot Aspect Ratio and Orientation Imaging of Nanoparticles
Plasmonic nanoparticles
with surface plasmon resonance (SPR) and
scattering response dependent on their geometry and surrounding environment
are predestinated to be used as optical probes for sensing and imaging.
Optical microscopy is capable of observing nanoparticles in various
media, but their geometry remains hidden below the diffraction limit.
Here, a wide-field optical imaging technique is demonstrated, restoring
the aspect ratio and orientation of individual nanoparticles via the
polarization anisotropy (PA) measurement of the scattered light. The
PA is mapped into a single nanoparticle image, formed by decomposing
the scattered light into longitudinal and transverse SPR modes and
manipulating their angular momentum. The wide-field images provide
the aspect ratio and orientation of many deposited nanoparticles allowing
their assessment in heterogeneous suspensions or time-resolved measurements.
In calibration experiments, orientation measurement accuracy and excellent
sensitivity to nanoparticles with specific aspect ratios are demonstrated.
Subsequently, the method is deployed in the automatic shape-dependent
categorization of hundreds of nanoparticles in a heterogeneous mixture.
The single-shot capability is demonstrated in the time-resolved imaging
of the electrophoretic deposition process