Size-dependent electronic decays and coherent phonon of CdSeTe quantum dots in glass matrix

• Our signal noise ratio of single color pump–probe measurement is bigger than 105.
• Obvious coherent phonon of CdSeTe QDs (R = 3.9 nm) in glass matrix was observed.
• Coherent phonon is attributed to resonant excitation because of Fröhlich coupling.
• The component with long lifetime (~ ns) under non-resonant excitation originated from heat accumulation.

The ultrafast decays of CdSexTe1 − x (x = 0.32) quantum dots in the glass matrix were reported by use of one-color pump probe experiments. The size varies from 7.8 to 22 nm, has a longer rising time and a much longer lifetime. Obvious coherent phonons and electronic decays of CdSexTe1 − x quantum dots (R = 3.9 nm) are found with the excitation of band-edge energy, but only long electronic decays of CdSexTe1 − x quantum dots (R = 5.3, 11.0 nm) are observed. Coherent phonon is attributed to resonant excitation because of Fröhlich coupling. The component with long lifetime under non-resonant excitation originated from heat accumulation.