Photoluminescence of Carbon Films

U N D E R   C O N S T R U C T I O N

  • Define: Photoluminescence (PL) and Photostimulated Luminescence (PSL).

  •        Photoluminescence (PL) is an optical phenomenon in which a material absorbs, upon excitation, an electromagnetic radiation of one wavelength and then re-radiates another electromagnetic radiation at a different wavelength. Photostimulated Luminescence (PSL) is also an optical phenomenon, just like photoluminescence (PL), which releases an electromagnetic radiation when a material with stored electron-hole pairs is stimulated with another electromagnetic radiation (usually a laser beam).

  • Describe the optical absorption phenomenon. Draw the log(absorption coefficient) vs photon energy plot, and mark the three absorption regimes.

  •        Optical absorption is a phenomenon in which the energy of a photon of an electromagnetic radiation is absorbed by the electrons of a material. Region A (called as Tauc Plot), Region B (Urbach Tail), and Region C are the three absorption regimes in the plot as shown below.

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  • Explain Beer-Lambert's law, Tauc's law, Urbach's tail.


  • Explain the optical absorption phenomenon by defects in materials.


  • What is the reason behind strong PL background in Raman spectra of hydrogenated carbon films?


  • How is the PL intensity related to hydrogen content in hydrogenated carbon films?


  • How is the PL intensity estimated in a Raman spectrum of hydrogenated carbon films?