scholarly journals Coherent Exciton Dynamics in Ensembles of Size-Dispersed CdSe Quantum Dot Dimers Probed via Ultrafast Spectroscopy: A Quantum Computational Study

2020 ◽  
Vol 10 (4) ◽  
pp. 1328 ◽  
Author(s):  
Hugo Gattuso ◽  
Barbara Fresch ◽  
Raphael D. Levine ◽  
Françoise Remacle
Keyword(s):  
Transient Absorption ◽  
Computational Study ◽  
Laser Pulses ◽  
Transient Absorption Spectroscopy ◽  
Basis Set ◽  
Charge Migration ◽  
Pump Probe ◽  
Electronic Response ◽  
Charge Transfer Excitons ◽  
Interdot Coupling

Interdot coherent excitonic dynamics in nanometric colloidal CdSe quantum dots (QD) dimers lead to interdot charge migration and energy transfer. We show by electronic quantum dynamical simulations that the interdot coherent response to ultrashort fs laser pulses can be characterized by pump-probe transient absorption spectroscopy in spite of the inevitable inherent size dispersion of colloidal QDs. The latter, leading to a broadening of the excitonic bands, induce accidental resonances that actually increase the efficiency of the interdot coupling. The optical electronic response is computed by solving the time-dependent Schrodinger equation including the interaction with the oscillating electric field of the pulses for an ensemble of dimers that differ by their size. The excitonic Hamiltonian of each dimer is parameterized by the QD size and interdot distance, using an effective mass approximation. Local and charge transfer excitons are included in the dimer basis set. By tailoring the QD size, the excitonic bands can be tuned to overlap and thus favor interdot coupling. Computed pump-probe transient absorption maps averaged over the ensemble show that the coherence of excitons in QD dimers that lead to interdot charge migration can survive size disorder and could be observed in fs pump-probe, four-wave mixing, or covariance spectroscopy.

scholarly journals Measuring the frequency chirp of extreme-ultraviolet free-electron laser pulses by transient absorption spectroscopy

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Thomas Ding ◽  
Marc Rebholz ◽  
Lennart Aufleger ◽  
Maximilian Hartmann ◽  
Veit Stooß ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Transient Absorption ◽  
Extreme Ultraviolet ◽  
Ultrashort Pulses ◽  
Laser Pulses ◽  
Transient Absorption Spectroscopy ◽  
Energy Structure ◽  
Frequency Chirp

AbstractHigh-intensity ultrashort pulses at extreme ultraviolet (XUV) and x-ray photon energies, delivered by state-of-the-art free-electron lasers (FELs), are revolutionizing the field of ultrafast spectroscopy. For crossing the next frontiers of research, precise, reliable and practical photonic tools for the spectro-temporal characterization of the pulses are becoming steadily more important. Here, we experimentally demonstrate a technique for the direct measurement of the frequency chirp of extreme-ultraviolet free-electron laser pulses based on fundamental nonlinear optics. It is implemented in XUV-only pump-probe transient-absorption geometry and provides in-situ information on the time-energy structure of FEL pulses. Using a rate-equation model for the time-dependent absorbance changes of an ionized neon target, we show how the frequency chirp can be directly extracted and quantified from measured data. Since the method does not rely on an additional external field, we expect a widespread implementation at FELs benefiting multiple science fields by in-situ on-target measurement and optimization of FEL-pulse properties.

Excited-State Bond Contraction and Charge Migration in a Platinum Dimer Complex Characterized by X-ray and Optical Transient Absorption Spectroscopy

2021 ◽  
Author(s):  
Nicholas P. Weingartz ◽  
Michael W. Mara ◽  
Subhangi Roy ◽  
Jiyun Hong ◽  
Arnab Chakraborty ◽  
...  
Keyword(s):  
Excited State ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Charge Migration ◽  
X Ray ◽  
Optical Transient

Physical mechanism on exciton-plasmon coupling revealed by femtosecond pump-probe transient absorption spectroscopy

2017 ◽  
Vol 3 ◽  
pp. 33-40 ◽  
Author(s):  
Weihua Lin ◽  
Ying Shi ◽  
Xianzhong Yang ◽  
Jing Li ◽  
En Cao ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Physical Mechanism ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Plasmon Coupling ◽  
Pump Probe

Ultrafast Nonlinear Optical Properties of Charge-Transfer Polymers

1998 ◽  
Vol 07 (03) ◽  
pp. 313-330 ◽  
Author(s):  
Duncan W. McBranch ◽  
Eric S. Maniloff ◽  
Dan Vacar ◽  
Alan J. Heeger
Keyword(s):  
Charge Transfer ◽  
Diffraction Efficiency ◽  
Nonlinear Optical ◽  
Transient Absorption ◽  
Laser Pulses ◽  
Transient Absorption Spectroscopy ◽  
Holographic Gratings ◽  
Ultrafast Laser Pulses ◽  
New Class ◽  
Localized Excitations

Charge-transfer polymers are a new class of nonlinear optical materials which can be used for generating femtosecond holographic gratings. Using semiconducting polymers sensitized with varying concentrations of C 60, holographic gratings were recorded by individual ultrafast laser pulses; the diffraction efficiency and time decay of the gratings were measured using nondegenerate four-wave mixing. Using a figure of merit for dynamic data processing, the temporal diffraction efficiency, this new class of materials exhibits between two and 12 orders of magnitude higher response than previous reports. The charge-transfer range at polymer/ C 60 interfaces was further studied using transient absorption spectroscopy. The fact that charge transfer occurs in the picosecond-time scale in bilayer structures (thickness 200 Å) implies that diffusion of localized excitations to the interface is not the dominant mechanism; the charge-transfer range is a significant fraction of the film thickness. From analysis of the excited state decay curves, we estimate the charge-transfer range to be 80 Å and interpret that range as resulting from quantum delocalization of the photoexcitations.

scholarly journals Frequency-domain “single-shot” ultrafast transient absorption spectroscopy using chirped laser pulses

2004 ◽  
Vol 96 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Ilya A. Shkrob ◽  
Dmitri A. Oulianov ◽  
Robert A. Crowell ◽  
Stanislas Pommeret
Keyword(s):  
Frequency Domain ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Laser Pulses ◽  
Transient Absorption Spectroscopy ◽  
Single Shot ◽  
Ultrafast Transient Absorption ◽  
Ultrafast Transient Absorption Spectroscopy

Single-shot transient absorption spectroscopy with a 45  ps pump-probe time delay range

2018 ◽  
Vol 43 (3) ◽  
pp. 371 ◽  
Author(s):  
Kelly S. Wilson ◽  
Cathy Y. Wong
Keyword(s):  
Time Delay ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Single Shot ◽  
Pump Probe

Single-shot transient absorption spectroscopy of an organic film

MRS Advances ◽  
2018 ◽  
Vol 3 (59) ◽  
pp. 3453-3457 ◽  
Author(s):  
Kelly S. Wilson ◽  
Madelyn N. Scott ◽  
Cathy Y. Wong
Keyword(s):  
Transient Absorption ◽  
Film Formation ◽  
Signal To Noise Ratio ◽  
Transient Absorption Spectroscopy ◽  
Organic Films ◽  
Single Shot ◽  
Organic Film ◽  
Pump Probe ◽  
Exciton Dynamics ◽  
Absorption Measurements

ABSTRACTWe report single-shot transient absorption (SSTA) measurements of an organic film of 3,3’-Diethyloxatricarbocyanine iodide (DOTCI). In SSTA, the pump-probe time delay is spatially encoded by using a tilted pump pulse. Translation of the sample during SSTA measurements averages over any spatial heterogeneity in the film. We demonstrate that exciton dynamics measured with the single-shot technique agrees with traditional transient absorption measurements of the same film. A signal-to-noise ratio of ∼40 is achieved in 10 s. The ability to measure exciton dynamics in organic films will enable future SSTA measurements of exciton dynamics during the molecular aggregation events that result in film formation.

scholarly journals Photophysical and photochemical applications of femtosecond time-resolved transient absorption spectroscopy

2001 ◽  
Vol 3 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Paolo Foggi ◽  
Laura Bussotti ◽  
Frederik V. R. Neuwahl
Keyword(s):  
Transient Absorption ◽  
Picosecond Laser ◽  
Laser Pulses ◽  
Transient Absorption Spectroscopy ◽  
Relaxation Processes ◽  
Time Resolved ◽  
Molecular Systems ◽  
Aromatic Molecules ◽  
Experimental Apparatus ◽  
Mathematical Formulas

The aim of this paper is to provide the main pieces of information concerning the application of transient absorption (TA) spectroscopy with sub-picosecond laser pulses. A description of the experimental apparatus and of some detection schemes are included together with the most common mathematical formulas utilized to analyze the signals. The results, recently obtained in our laboratory and presented here, concern the investigation of the excited state dynamics of simple molecular systems. Examples of the measurements of the relaxation processes occurring in the lowest excited states of some aromatic molecules will be discussed in order to show the potentiality of the technique.

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