Cathodoluminescence microscopy: Optical imaging and spectroscopy with deep-subwavelength resolution

Abstract

This article describes a new microscope, based on angle-resolved cathodoluminescence (CL) imaging spectroscopy, which enables optical imaging and spectroscopy at deepsubwavelength spatial resolution. We used a free electron beam in a scanning electron microscope as a direct excitation source for polarizable materials, and we collected the emitted coherent visible/infrared CL radiation using a specially designed optical collection system that is integrated in the electron microscope. We have demonstrated the use of this new technique for the excitation of plasmons in single metal nanoparticles, surface plasmon polaritons at metal surfaces, resonant Mie modes in dielectric nanostructures, and cavity modes and Bloch modes in photonic crystals. Using angle-resolved detection, we are able to derive the nature of localized modes and the dispersion of propagation modes in dielectric and plasmonic geometries. An outlook about new directions and applications of CL imaging spectroscopy is also provided.

Effectiveness of different final irrigation techniques and placement of endodontic sealer into dentinal tubules

“…12 Cathodoluminescence is a powerful tool in the field of quantum emitters, 29 in which electrons impacting a luminescent material result in the emission of photons that may present wavelengths in the visible spectrum. 30 CLSM as well as SEM evaluations allow the measurement of maximum depth and percentage of sealer penetration. SEM is limited to a superficial view.…”

Spectrally and Spatially Resolved Smith-Purcell Radiation in Plasmonic Crystals with Short-Range Disorder

“…Such a measurement is particularly interesting for light-electron interactions involving structural defects, or when resolving the dynamics of surface-emitted light. In contrast, other CL setups collect the emitted light with a fiber [18,47] or a parabolic mirror, with the latter allowing angular-resolved CL collection [19,[48][49][50][51]. Yet, despite these techniques, no direct spatially resolved imaging of the light emission has been performed before, to the best of our knowledge.…”

“…To date, angularly resolved CL collection has been particularly useful for measuring local photonic and plasmonic cavities and resonances on a surface, when excited locally by a free electron and then emitting to the hemisphere above the surface [48][49][50][51]. However, angular CL only records the emission angle and does not provide a direct way to detect the origin of the emitted light; this is particularly important in cases where light propagates away from the local excitation spot before it is emitted.…”

“…These include the excitation of dipoles in localized resonances and other kinds of CL-related effects [18,[47][48][49][50][51], some coming from atomic transitions of The sample is held so that its surface is almost parallel to the path of the electron beam. The emitted light is collected by an objective, directing the emitted light into an enclosure box holding the rest of the optical setup.…”

Scanning cathodoluminescence microscopy: applications in semiconductor and metallic nanostructures

“…CL spectroscopy is usually operated in scanning electron microscopy (SEM) 11 , although it is also possible to perform measurements in transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) 12 . When the focused electron beam passes through the aperture hole of the parabolic mirror and hits on the sample surface, CL generated from the luminescent material can be reflected by the mirror and collected by photomultiplier tube (PMT) or a charge-coupled device (CCD) where CL images can be obtained.…”