scholarly journals Evidence for direct molecular oxygen production in CO2 photodissociation

Science ◽  
2014 ◽  
Vol 346 (6205) ◽  
pp. 61-64 ◽  
Author(s):  
Zhou Lu ◽  
Yih Chung Chang ◽  
Qing-Zhu Yin ◽  
C. Y. Ng ◽  
William M. Jackson
Keyword(s):  
Carbon Dioxide ◽  
Vacuum Ultraviolet ◽  
Theoretical Calculations ◽  
Velocity Map Imaging ◽  
Exit Channel ◽  
Oxygen Production ◽  
Pump Probe ◽  
Primary Products ◽  
Imaging Detection ◽  
Probe Spectroscopy

Photodissociation of carbon dioxide (CO2) has long been assumed to proceed exclusively to carbon monoxide (CO) and oxygen atom (O) primary products. However, recent theoretical calculations suggested that an exit channel to produce C + O2 should also be energetically accessible. Here we report the direct experimental evidence for the C + O2 channel in CO2 photodissociation near the energetic threshold of the C(3P) + O2(X3Σg–) channel with a yield of 5 ± 2% using vacuum ultraviolet laser pump-probe spectroscopy and velocity-map imaging detection of the C(3PJ) product between 101.5 and 107.2 nanometers. Our results may have implications for nonbiological oxygen production in CO2-heavy atmospheres.

scholarly journals Orbital-Dependent Photodynamics of Strongly Correlated Clusters

2021 ◽  
Author(s):  
Jacob Garcia ◽  
Scott Sayres
Keyword(s):  
Theoretical Calculations ◽  
Advanced Materials ◽  
Strongly Correlated ◽  
Relaxation Dynamics ◽  
Pump Probe ◽  
Defect Sites ◽  
Atomic Precision ◽  
Bulk Scale ◽  
Probe Spectroscopy

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.

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

Processes ◽  
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.

scholarly journals Ultraviolet spectroscopy of pressurized and supercritical carbon dioxide

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Timothy W. Marin ◽  
Ireneusz Janik
Keyword(s):  
Carbon Dioxide ◽  
Potential Energy Surfaces ◽  
Vacuum Ultraviolet ◽  
Electronic Absorption Spectra ◽  
Industrial Applications ◽  
Ultraviolet Spectroscopy ◽  
Collisional Broadening ◽  
Thermodynamic Critical Point ◽  
State Potential ◽  
Energy Surfaces

AbstractCarbon dioxide (CO2) is prevalent in planetary atmospheres and sees use in a variety of industrial applications. Despite its ubiquitous nature, its photochemistry remains poorly understood. In this work we explore the density dependence of pressurized and supercritical CO2 electronic absorption spectra by vacuum ultraviolet spectroscopy over the wavelength range 1455-2000 Å. We show that the lowest absorption band transition energy is unaffected by a density increase up to and beyond the thermodynamic critical point (137 bar, 308 K). However, the diffuse vibrational structure inherent to the spectrum gradually decreases in magnitude. This effect cannot be explained solely by collisional broadening and/or dimerization. We suggest that at high densities close proximity of neighboring CO2 molecules with a variety of orientations perturbs the multiple monomer electronic state potential energy surfaces, facilitating coupling between binding and dissociative states. We estimate a critical radius of ~4.1 Å necessary to cause such perturbations.

Classical theory of ultrafast pump-probe spectroscopy: Applications to I2 photodissociation in Ar solution

1994 ◽  
Vol 61 (1-3) ◽  
pp. 153-165 ◽  
Author(s):  
Robert M. Whitnell ◽  
Kent R. Wilson ◽  
YiJing Yan ◽  
Ahmed H. Zewail
Keyword(s):  
Classical Theory ◽  
Pump Probe ◽  
Probe Spectroscopy

Coherent pump–probe spectroscopy of a Λ system with a close lying excited level

2013 ◽  
Vol 88 (6) ◽  
pp. 065404 ◽  
Author(s):  
Niharika Singh ◽  
Ayan Ray ◽  
R D'Souza ◽  
Q V Lawande ◽  
B N Jagatap
Keyword(s):  
Excited Level ◽  
Pump Probe ◽  
Probe Spectroscopy

Ultrafast pump-probe spectroscopy of native etiolated oat phytochrome

Biochemistry ◽  
1993 ◽  
Vol 32 (29) ◽  
pp. 7512-7518 ◽  
Author(s):  
Sergei Savikhin ◽  
Todd Wells ◽  
Pill Soon Song ◽  
Walter S. Struve
Keyword(s):  
Pump Probe ◽  
Probe Spectroscopy

Ultrafast pump-probe spectroscopy: femtosecond dynamics in Liouville space

1989 ◽  
Vol 93 (25) ◽  
pp. 8149-8162 ◽  
Author(s):  
Yi Jing Yan ◽  
Laurence E. Fried ◽  
Shaul Mukamel
Keyword(s):  
Pump Probe ◽  
Liouville Space ◽  
Femtosecond Dynamics ◽  
Probe Spectroscopy

Investigation of Local Dynamics on the Sub-micron Scale in Organic Blends Using an Ultrafast Confocal Microscope

2010 ◽  
Vol 1270 ◽  
Author(s):  
Giulia Grancini ◽  
Dario Polli ◽  
Jenny Clark ◽  
Tersilla Virgili ◽  
Giulio Cerullo ◽  
...  
Keyword(s):  
Excited State ◽  
Confocal Microscopy ◽  
Polymer Blends ◽  
Spatial Resolution ◽  
Temporal Resolution ◽  
Electronic States ◽  
Pump Probe ◽  
Peculiar Behaviour ◽  
Spatio Temporal ◽  
Probe Spectroscopy

AbstractWe introduce a novel instrument combining femtosecond pump-probe spectroscopy and confocal microscopy for spatio-temporal imaging of excited-state dynamics of phase-separated polymer blends. Phenomena occurring at interfaces between different materials are crucial for optimizing the device performances, but are poorly understood due to the variety of possible electronic states and processes involved and to their complicated dynamics. Our instrument (with 200-fs temporal resolution and 300-nm spatial resolution) provides new insights into the properties of polymer blends, revealing spatially variable photo-relaxation paths and dynamics and highlighting a peculiar behaviour at the interface between the phase-separated domains.

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