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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Cathodoluminescence | 2/2 | https://en.wikipedia.org/wiki/Cathodoluminescence | reference | science, encyclopedia | 2026-05-05T10:03:53.622728+00:00 | kb-cron |
In scanning electron microscopes a focused beam of electrons impinges on a sample and induces it to emit light that is collected by an optical system, such as an elliptical mirror. From there, a fiber optic will transfer the light out of the microscope where it is separated into its component wavelengths by a monochromator and is then detected with a photomultiplier tube. By scanning the microscope's beam in an X-Y pattern and measuring the light emitted with the beam at each point, a map of the optical activity of the specimen can be obtained (cathodoluminescence imaging). Instead, by measuring the wavelength dependence for a fixed point or a certain area, the spectral characteristics can be recorded (cathodoluminescence spectroscopy). Furthermore, if the photomultiplier tube is replaced with a CCD camera, an entire spectrum can be measured at each point of a map (hyperspectral imaging). Moreover, the optical properties of an object can be correlated to structural properties observed with the electron microscope. The primary advantages to the electron microscope based technique is its spatial resolution. In a scanning electron microscope, the attainable resolution is on the order of a few ten nanometers, while in a (scanning) transmission electron microscope (TEM), nanometer-sized features can be resolved. Additionally, it is possible to perform nanosecond- to picosecond-level time-resolved measurements if the electron beam can be "chopped" into nano- or pico-second pulses by a beam-blanker or with a pulsed electron source. These advanced techniques are useful for examining low-dimensional semiconductor structures, such a quantum wells or quantum dots. While an electron microscope with a cathodoluminescence detector provides high magnification, an optical cathodoluminescence microscope benefits from its ability to show actual visible color features directly through the eyepiece. More recently developed systems try to combine both an optical and an electron microscope to take advantage of both these techniques.
== Extended applications == Although direct bandgap semiconductors such as GaAs or GaN are most easily examined by these techniques, indirect semiconductors such as silicon also emit weak cathodoluminescence, and can be examined as well. In particular, the luminescence of dislocated silicon is different from intrinsic silicon, and can be used to map defects in integrated circuits. Recently, cathodoluminescence performed in electron microscopes is also being used to study surface plasmon resonances in metallic nanoparticles. Surface plasmons in metal nanoparticles can absorb and emit light, though the process is different from that in semiconductors. Similarly, cathodoluminescence has been exploited as a probe to map the local density of states of planar dielectric photonic crystals and nanostructured photonic materials.
== See also == Electron-stimulated luminescence Luminescence Photoluminescence Scanning electron microscopy
== References ==
== Further reading == Coenen, T. (2014). Angle-resolved cathodoluminescence nanoscopy (Thesis). University of Amsterdam. hdl:11245/1.417564. Electron beams set nanostructures aglow [PDF], E. S. Reich, Nature 493, 143 (2013) Lähnemann, J. (2013). Luminescence of group-III-V nanowires containing heterostructures (pdf) (PhD Thesis). Humboldt-Universität zu Berlin. Kuttge, M. (2009). Cathodoluminescence plasmon microscopy (pdf) (Thesis). Utrecht University. Scanning Cathodoluminescence Microscopy, C. M. Parish and P. E. Russell, in Advances in Imaging and Electron Physics, V.147, ed. P. W. Hawkes, P. 1 (2007) Quick look cathodoluminescence analyses and their impact on the interpretation of carbonate reservoirs. Case study of mid-Jurassic oolitic reservoirs in the Paris Basin Archived 2018-09-25 at the Wayback Machine, B. Granier and C. Staffelbach (2009) Cathodoluminescence Microscopy of Inorganic Solids,, B. G. Yacobi and D. B. Holt, New York, Springer (1990)
== External links == Application laboratory time-resolved cathodoluminescence spectroscopy at Paul-Drude-Institut LumiSpy – Luminescence spectroscopy data analysis with python Scientific Results about High Spatial Resolution Cathodoluminescence Archived 2020-07-27 at the Wayback Machine