The mechanisms of temperature-dependent nonradiative processes (thermal quenching) in NPs(CdSe, CdSe, ZnSe, and CdTe ) which exhibit reversible thermal quenching are of two types- Thermal quenching having dynamic (affecting the luminescence lifetimes) and static (affecting the fraction of particles that are bright versus dark) components.

In both the cases, the extent is strongly dependent on the composition of the surface( nature of the surface ligands or types of particles) and the density of empty surface chalcogenide orbitals and the valence band energies.

[1] Dynamic thermal quenching is due to thermally activated trapping dynamics that occur on the same time scale as the radiative lifetime.

[I] In the static thermal quenching, the dominant mechanism involves thermal promotion of valence band electrons to empty chalcogenide (p) orbitals on the particle surfaces. This leaves a hole in the valence band, and subsequent photoexcitation produces a positive trion*. The trion undergoes relatively rapid nonradiative Auger relaxation**, rendering the particle dark.

* A trion is a localized excitation which consists of three charged quasiparticles. A negative trion consists of two electrons and one hole and a positive trion consists of two holes and one electron and can be considered to be somewhat similar to an excitation which is a complex of one electron and one hole. The trion has a ground state spin = 1/2 and an excited state spin = 3/2. Trion states were predicted theoretically and then observed experimentally in various optically excited semiconductors especially in quantum dots and quantum well structures.

** Auger effect is based on the analysis of energetic electrons emitted from an excited atom after a series of internal relaxation events (See under Auger electron spectroscopy).

No ! PL of a direct band gap semiconductor completely vanishes after deposition of metal nanoparticles. I wanted to know more about that.

The quenching of PL intensity of semiconductors in presence of metal nanoparticles are most the cases associated with resonance energy transfer phenomena. The best thing is to first analyse if there exist any overlapping between metal nanoparticle surface plasmon absorption spectra and emission spectra of semiconductor.

The mechanisms of temperature-dependent nonradiative processes (thermal quenching) in NPs(CdSe, CdSe, ZnSe, and CdTe ) which exhibit reversible thermal quenching are of two types- Thermal quenching having dynamic (affecting the luminescence lifetimes) and static (affecting the fraction of particles that are bright versus dark) components.

In both the cases, the extent is strongly dependent on the composition of the surface( nature of the surface ligands or types of particles) and the density of empty surface chalcogenide orbitals and the valence band energies.

[1] Dynamic thermal quenching is due to thermally activated trapping dynamics that occur on the same time scale as the radiative lifetime.

[I] In the static thermal quenching, the dominant mechanism involves thermal promotion of valence band electrons to empty chalcogenide (p) orbitals on the particle surfaces. This leaves a hole in the valence band, and subsequent photoexcitation produces a positive trion*. The trion undergoes relatively rapid nonradiative Auger relaxation**, rendering the particle dark.

* A trion is a localized excitation which consists of three charged quasiparticles. A negative trion consists of two electrons and one hole and a positive trion consists of two holes and one electron and can be considered to be somewhat similar to an excitation which is a complex of one electron and one hole. The trion has a ground state spin = 1/2 and an excited state spin = 3/2. Trion states were predicted theoretically and then observed experimentally in various optically excited semiconductors especially in quantum dots and quantum well structures.

** Auger effect is based on the analysis of energetic electrons emitted from an excited atom after a series of internal relaxation events (See under Auger electron spectroscopy).

Thanks for such an elaborate answer, manohar.

@Ehsan. brother, do you have paper that elaborate those ideas ? it will be my pleasure to know more about it. thank you

Look at Section 5.6.3 in the book of J. Garcia Sole et al. "An introduction to the optical spectroscopy of inorganic solids"

Dear. Ehsan. i need proper link about this article

Quenching may occur due to several facts. Please go through...

http://onlinelibrary.wiley.com/doi/10.1002/adom.201601021/abstract

Thanks.