The key difference between cathodoluminescence and photoluminescence is that cathodoluminescence involves the emission of light obtained by electron excitation, whereas photoluminescence involves the emission of light obtained by optical excitation.
Luminescence is a phenomenon that involves the absorption of light at a specific wavelength via a chemical molecule and the emission of light at a longer wavelength. These are called the excitation wavelength and the emission wavelength, respectively.
CONTENTS
1. Overview and Key Difference
2. What is Cathodoluminescence
3. What is Photoluminescence
4. Cathodoluminescence vs Photoluminescence in Tabular Form
5. Summary – Cathodoluminescence vs Photoluminescence
What is Cathodoluminescence?
Cathodoluminescence is an electromagnetic and optical phenomenon where electrons impacting a luminescent material cause the emission of photons, which may have wavelengths in the visible spectrum. A common luminescent material is phosphor. When we consider some real-life applications, the generation of light by an electron beam that is scanning the phosphor-coated inner surface of the screen of a television that is using a cathode ray tube is an example of athodoluminescence. This optical phenomenon is the inverse of the photoelectric effect, where electron emission is induced by irradiation with photons.
Cathodoluminescence has many applications in microscopy, such as in geology, mineralogy, materials science, and semiconductor engineering. In these fields, a scanning electron microscope is fitted with a cathodoluminescence detector. Sometimes an optical cathodoluminescence microscope is useful in examining internal structures of semiconductors, rocks, ceramics, glass, etc.
What is Photoluminescence?
Photoluminescence is a form of luminescence that occurs with photoexcitation via photon absorption. This light emission occurs when a substance absorbs electromagnetic radiation and re-emits the radiation. This process initiates with photoexcitation. This means the electrons of the substance undergo excitations when the substance absorbs photons, and electrons move to higher energy states from lower energy states. Following these excitations, there are relaxation processes as well. In the relaxation step, photons are re-radiated or emitted. The time period between the absorption and emission of photons may vary depending on the substance.
There are several forms of photoluminescence that differ from each other according to several parameters. When considering the wavelength of absorbed and emitted wavelengths of photons, there are two major types as fluorescence and resonance fluorescence. In fluorescence, the wavelength of emitted radiation is lower than the wavelength of absorbed wavelength. In resonance fluorescence, the absorbed and emitted radiation have equivalent wavelengths.
What is the Difference Between Cathodoluminescence and Photoluminescence?
Luminescence is an optical phenomenon. It can be found in different types, and cathodoluminescence and photoluminescence are two such types. Cathodoluminescence is an electromagnetic and optical phenomenon where electrons impacting a luminescent material cause the emission of photons, which may have wavelengths in the visible spectrum. Photoluminescence, on the other hand, is a form of luminescence that occurs with photoexcitation via photon absorption. The key difference between cathodoluminescence and photoluminescence is that cathodoluminescence involves the emission of light obtained by electron excitation, whereas photoluminescence involves the emission of light obtained by optical excitation.
Below is a summary of the difference between cathodoluminescence and photoluminescence in tabular form for side-by-side comparison.
Summary – Cathodoluminescence vs Photoluminescence
Cathodoluminescence is an electromagnetic and optical phenomenon where electrons impacting a luminescent material cause the emission of photons, which may have wavelengths in the visible spectrum. Photoluminescence is a form of luminescence that occurs with photoexcitation via photon absorption. The key difference between cathodoluminescence and photoluminescence is that cathodoluminescence involves the emission of light obtained by electron excitation, whereas photoluminescence involves the emission of light obtained by optical excitation.
Reference:
1. “Cathodoluminescence.” An Overview | ScienceDirect Topics.
Image Courtesy:
1. “Diamond (side view).” By Pavel.Somov – Own work (CC BY 4.0) via Commons Wikimedia
2. “Fluorescence Rainbow” By Maxim Bilovitskiy – Own work (CC BY-SA 4.0) via Commons Wikimedia