Ultrafast polarization-modulation transient spectroscopy to study electronic excited state dynamics in biological molecules

2020 ◽  
Author(s):  
Ioanna Gorbunova ◽  
Nikolay Bezverkhnii ◽  
Maxim Sasin ◽  
Idris Gadzhiev ◽  
Daria Gorbenko ◽  
...  
Keyword(s):  
Excited State ◽  
Biological Molecules ◽  
Polarization Modulation ◽  
Excited State Dynamics ◽  
Electronic Excited State ◽  
Transient Spectroscopy

Revisiting the spectroscopy of xanthine derivatives: theobromine and theophylline

2019 ◽  
Vol 21 (48) ◽  
pp. 26430-26437 ◽  
Author(s):  
Ander Camiruaga ◽  
Imanol Usabiaga ◽  
Viola C. D’mello ◽  
Gustavo A. García ◽  
Sanjay Wategaonkar ◽  
...  
Keyword(s):  
Excited State ◽  
Excited State Dynamics ◽  
Electronic Excited State ◽  
Xanthine Derivatives

Methylation deeply influences the electronic excited state dynamics of xanthines.

scholarly journals On the origin of spatially dependent electronic excited-state dynamics in mixed hybrid perovskite thin films

2019 ◽  
Vol 58 (4) ◽  
Author(s):  
Ying-Zhong Ma ◽  
Benjamin Doughty ◽  
Mary Jane Simpson ◽  
Sanjib Das ◽  
Kai Xiao
Keyword(s):  
Thin Films ◽  
Excited State ◽  
Transient Absorption ◽  
Signal Amplitude ◽  
Spatial Location ◽  
Optoelectronic Device ◽  
Dynamical Process ◽  
Spectroscopic Techniques ◽  
Excited State Dynamics ◽  
Electronic Excited State

The fundamental photophysics underlying the remarkable performance of organic-inorganic hybrid perovskites in optoelectronic device applications has been increasingly studied using complementary spectroscopic techniques. However, the spatially heterogeneous polycrystalline morphology of the solution-processed thin films is often overlooked in conventional ensemble measurements and therefore the reported results are averaged over hundreds or even thousands of nano- and micro-crystalline grains. Here, we apply femtosecond transient absorption microscopy to spatially and temporally probe ultrafast electronic excited-state dynamics in chloride containing mixed lead halide perovskite (CH3NH3PbI3–xClx) thin films. We found that the electronic excited-state relaxation kinetics are extremely sensitive to the spatial location probed, which was manifested by position-dependent transient absorption signal amplitude and decay behaviour, along with an obvious rise component at some positions. The analysis of transient absorption kinetics acquired at several distinct spatial positions enabled us to identify Auger recombination as the dominant mechanism underlying the initial portions of the spatially dependent dynamics with variable rate constants. The different rates observed suggest occurrence of distinct local electronic structures and variable contributions from impurities/defects and phonons in this nonlinear dynamical process.

scholarly journals Methods to Calculate Electronic Excited-state Dynamics For Molecules on Large Metal Clusters with Many States: Ensuring Fast Overlap Calculations and a Robust Choice of Phase

2021 ◽  
Author(s):  
Hsing-Ta Chen ◽  
Junhan Chen ◽  
Vale Cofer-Shabica ◽  
Zeyu Zhou ◽  
Vishikh Athavale ◽  
...  
Keyword(s):  
Excited State ◽  
Collective Excitation ◽  
Metal Cluster ◽  
Computational Cost ◽  
Electronic States ◽  
Relaxation Processes ◽  
Nuclear Dynamics ◽  
Excited State Dynamics ◽  
Electronic Excited State ◽  
Unified Protocol

We present an efficient set of methods for propagating excited-state dynamics involving a large number of electronic states based on a CIS electronic state overlap scheme. Specifically, (i) following Head-Gordon et al, we implement an exact evaluation of the overlap of singly-excited electronic states at different nuclear geometries using a biorthogonal basis, and (ii) we employ a unified protocol for choosing the correct phase for each adiabat at each geometry. For many-electron systems, the combination of these techniques significantly reduces the computational cost of integrating the electronic Schrodinger equation and imposes minimal overhead on top of the underlying electronic structure calculation. As a demonstration, we calculate the electronic excited-state dynamics for a hydrogen molecule scattering off a silver metal cluster, focusing on high-lying excited states where many electrons can be excited collectively and crossings are plentiful. Interestingly, we find that the high-lying, plasmon-like collective excitation spectrum changes with nuclear dynamics, highlighting the need to simulate non-adiabatic nuclear dynamics and plasmonic excitations simultaneously. In the future, the combination of methods presented here should help theorists build a mechanistic understanding of plasmon-assisted charge transfer and excitation energy relaxation processes near a nanoparticle or metal surface.

Renilla Bioluminescence: A Morphologic Approach to the Location of Photocytes

1974 ◽  
Vol 32 ◽  
pp. 208-209
Author(s):  
Ben O. Spurlock ◽  
Milton J. Cormier
Keyword(s):  
Excited State ◽  
Ground State ◽  
Molecular Basis ◽  
Light Emission ◽  
Chemical Basis ◽  
Electronic Excited State ◽  
Colonial Form ◽  
The Common ◽  
Eighteenth And Nineteenth Centuries ◽  
Catalyzed Oxidation

The phenomenon of bioluminescence has fascinated layman and scientist alike for many centuries. During the eighteenth and nineteenth centuries a number of observations were reported on the physiology of bioluminescence in Renilla, the common sea pansy. More recently biochemists have directed their attention to the molecular basis of luminosity in this colonial form. These studies have centered primarily on defining the chemical basis for bioluminescence and its control. It is now established that bioluminescence in Renilla arises due to the luciferase-catalyzed oxidation of luciferin. This results in the creation of a product (oxyluciferin) in an electronic excited state. The transition of oxyluciferin from its excited state to the ground state leads to light emission.

Excited-State Dynamics in the RNA Nucleotide Uridine 5’-Monophosphate Investigated by Femtosecond Broadband Transient Absorption Spectroscopy

2019 ◽  
Author(s):  
Matthew M. Brister ◽  
Carlos Crespo-Hernández
Keyword(s):  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Transient Absorption ◽  
Electronic Energy ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Vibrationally Excited ◽  
Excited State Dynamics ◽  
Π State

<p></p><p> Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, but investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5’-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a longlived <sup>1</sup>n<sub>O</sub>π* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived <sup>3</sup>ππ* state in an ultrafast time scale. The results elucidate the electronic relaxation pathways and clarify earlier transient absorption experiments performed for uracil derivatives in solution. This mechanistic information is important because long-lived nπ* and ππ* excited states of both singlet and triplet multiplicities are thought to lead to the formation of harmful photoproducts.</p><p></p>

Modulation of Excited State Dynamics in Lead Halide Perovskite Films with Electrical Bias

2019 ◽  
Author(s):  
Gergely Samu ◽  
R.A. Scheidt ◽  
A. Balog ◽  
C. Janáky ◽  
P.V. Kamat
Keyword(s):  
Excited State ◽  
Excited State Dynamics ◽  
Halide Perovskite ◽  
Electrical Bias ◽  
Lead Halide
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