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Past Events
Public Seminar of RPg Student:
Acoustic Phonon Effect in Lorentz Broadening of So-called Zero-phonon Luminescence Lines in Solids
| Speaker: | Mr. Yitian BAO |
| Affiliation: | The University of Hong Kong |
| Date: | September 4, 2018 (Tuesday) |
| Time: | 1:20 p.m. |
| Venue: | Rm 105, 1/F, Chong Yuet Ming Physics Building, HKU |
Abstract
It has been known that phonons play an essential role in spectral line broadening in solids. However, it is extremely difficult to quantitatively handle the phonon effect in spectral line broadening in solids due to the complicated many-body nature of such issue. As an outcome, so-called zero-phonon lines (ZPL) have to be assumed and adopted. In this work, we attempt to reconsider the natural and homogeneous broadening of ZPL lines by countless acoustic phonons. Starting from a general approach developed by O’Rouke (Phys. Rev. 91, 265 (1953)), we derive unified formulas to calculate luminescence spectrum of electron-phonon coupling system. It is revealed that so-called ZPL lines exhibit almost perfect Lorentz lineshape broadened by many acoustic phonons, especially at low temperatures. In addition, theoretical formulas have been applied to quantitatively interpret the variable-temperature photoluminescence spectra of several realistic samples including ZnO and diamond. Good agreement between theory and experiment leads to a state-of-the-art understanding of the crucial role of acoustic phonons in the natural and homogeneous broadening of ZPL luminescence lines of trapped electron in solids.
Anyone interested is welcome to attend.