Nonequilibrium electron dynamics in pump-probe spectroscopy: Role of excited phonon populations

Understanding the role of defect sites on the mechanism and lifetime of photoexcited state relaxation is critical for the ration-al design of advanced materials. Here, the ultrafast electronic relaxation dynamics of neutral nickel oxide clusters were inves-tigated with femtosecond pump-probe spectroscopy and supported with theoretical calculations to reveal that their excited state lifetimes are strongly dependent on the nature of the electronic transition. Absorption of a UV photon produces short lived (lifetime ~110 fs) dynamics in stoichiometric (NiO)n clusters (n < 6) that are attributed to a ligand to metal charge transfer (LMCT) and produces metallic-like electron-electron scattering. Oxygen vacancies introduce excitations with Ni-3d→Ni-4s and 3d→4p character, which increases the lifetimes of the sub-picosecond response by up to 80% and enables the formation of long-lived (lifetimes > 2.5 ps) states. The atomic precision and tunability of gas phase clusters are employed to highlight a unique reliance on the Ni orbital contributions to the photoexcited lifetimes, providing new insights to the anal-ogous band edge excitation dynamics of strongly correlated bulk-scale NiO materials.

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TWO-TEMPERATURE MODEL OF NONEQUILIBRIUM ELECTRON RELAXATION: A REVIEW

International Journal of Modern Physics B ◽

10.1142/s0217979210055366 ◽

2010 ◽

Vol 24 (09) ◽

pp. 1141-1158 ◽

Cited By ~ 27

Author(s):

NAVINDER SINGH

Keyword(s):

Electronic Relaxation ◽

Temperature Model ◽

Open Problems ◽

Nonequilibrium Electron ◽

Pump Probe ◽

Nano Scale ◽

Electron Relaxation ◽

Probe Spectroscopy ◽

Kinetics Of ◽

Two Temperature

The present paper is a review of the phenomena related to nonequilibrium electron relaxation in bulk and nano-scale metallic samples. The workable Two-Temperature Model (TTM) based on Boltzmann–Bloch–Peierls kinetic equation has been applied to study the ultra-fast (femto-second) electronic relaxation in various metallic systems. The advent of new ultra-fast (femto-second) laser technology and pump-probe spectroscopy has produced wealth of new results for micro- and nano-scale electronic technology. The aim of this paper is to clarify the TTM, conditions of its validity and nonvalidity, its modifications for nano-systems, to sum-up the progress, and to point out open problems in this field. We also give a phenomenological integro-differential equation for the kinetics of nondegenerate electrons that goes beyond the TTM.

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Energy Focus: 20-fs resolution pump-probe spectroscopy reveals role of hot exciton dissociation in polymer solar cells

MRS Bulletin ◽

10.1557/mrs.2013.31 ◽

2013 ◽

Vol 38 (2) ◽

pp. 119-119

Author(s):

Elsa Couderc

Keyword(s):

Solar Cells ◽

Polymer Solar Cells ◽

Exciton Dissociation ◽

Pump Probe ◽

Probe Spectroscopy

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Simulation of pump–probe spectroscopy of a highly-charged diatomic molecule: Role of intermediate charged states and electronic and vibrational excitation in the multiple ionization of Cl2 and strong-field spectroscopy of Cl23+

The Journal of Chemical Physics ◽

10.1063/1.1506684 ◽

2002 ◽

Vol 117 (15) ◽

pp. 6991-7001 ◽

Cited By ~ 3

Author(s):

R. J. Verver ◽

J. S. Wright ◽

M. Yu. Ivanov

Keyword(s):

Diatomic Molecule ◽

Strong Field ◽

Vibrational Excitation ◽

Pump Probe ◽

Field Spectroscopy ◽

Multiple Ionization ◽

Probe Spectroscopy

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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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