Detecting strain wave propagation through quantum dots by pump-probe spectroscopy: A theoretical analysis

Femtosecond pump–probe spectroscopy reveals ultrafast carrier dynamics in mid-infrared (MIR) colloidal HgTe nanoparticles with a bandgap of 2.5 μm at a mean energy dissipation rate of 0.36 eV ps−1 irrespective of excitation wavelength.

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Long-Lifetime Nonlinear Absorption of PbS Quantum Dots

MRS Proceedings ◽

10.1557/proc-737-e13.23 ◽

2002 ◽

Vol 737 ◽

Author(s):

Feiran Huang ◽

Aleksey Filin ◽

Pratima G.N. Rao ◽

Robert H. Doremus ◽

Peter D. Persans

Keyword(s):

Quantum Dots ◽

Narrow Size Distribution ◽

Optical Absorption Spectra ◽

Electron Hole ◽

Pump Probe ◽

Electron Hole Pair ◽

Long Lifetime ◽

Average Size ◽

Probe Spectroscopy ◽

Pbs Quantum Dots

ABSTRACTWe have fabricated PbS particles in glass of average size from 1.2 nm to 3 nm. This allows us to tune the energy of the lowest electron-hole pair transition from 1.7 eV to 0.8 eV respectively. Optical absorption spectra show a pronounced quantum peak, implying a narrow size distribution. We have performed pump-probe spectroscopy where the probe is cw and the pump is nanosecond; this allows us to investigate a wide time scale. We have observed bleaching of the lowest quantum peak with lifetimes of ∼2 microseconds. We interpret this in terms of trapped carriers. Phenomenological description of observed effect is also presented.

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Ultrafast Electron/Energy Transfer and Intersystem Crossing Mechanisms in BODIPY-Porphyrin Compounds

Processes ◽

10.3390/pr9020312 ◽

2021 ◽

Vol 9 (2) ◽

pp. 312

Author(s):

Yusuf Tutel ◽

Gökhan Sevinç ◽

Betül Küçüköz ◽

Elif Akhuseyin Yildiz ◽

Ahmet Karatay ◽

...

Keyword(s):

Energy Transfer ◽

Fluorescence Spectra ◽

Visible Region ◽

Energy Transfer Mechanism ◽

Free Base ◽

Pump Probe ◽

Harvesting Efficiency ◽

Probe Spectroscopy ◽

Absorption Features ◽

Transfer Mechanisms

Meso-substituted borondipyrromethene (BODIPY)-porphyrin compounds that include free base porphyrin with two different numbers of BODIPY groups (BDP-TTP and 3BDP-TTP) were designed and synthesized to analyze intramolecular energy transfer mechanisms of meso-substituted BODIPY-porphyrin dyads and the effect of the different numbers of BODIPY groups connected to free-base porphyrin on the energy transfer mechanism. Absorption spectra of BODIPY-porphyrin conjugates showed wide absorption features in the visible region, and that is highly valuable to increase light-harvesting efficiency. Fluorescence spectra of the studied compounds proved that BODIPY emission intensity decreased upon the photoexcitation of the BODIPY core, due to the energy transfer from BODIPY unit to porphyrin. In addition, ultrafast pump-probe spectroscopy measurements indicated that the energy transfer of the 3BDP-TTP compound (about 3 ps) is faster than the BDP-TTP compound (about 22 ps). Since the BODIPY core directly binds to the porphyrin unit, rapid energy transfer was seen for both compounds. Thus, the energy transfer rate increased with an increasing number of BODIPY moiety connected to free-base porphyrin.

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