scholarly journals Role of conical intersection seam topography in the chemiexcitation of 1,2-dioxetanes

2022 ◽  
Author(s):  
Ignacio Fdez. Galván ◽  
Anders Brakestad ◽  
Morgane Vacher
Keyword(s):  
Surface Topography ◽  
Excited States ◽  
Conical Intersection ◽  
Nonadiabatic Transitions

Chemiexcitation of 1,2-dioxetanes is initiated by the cleavage of the O–O bond, then the molecule enters a region where nonadiabatic transitions to excited states are feasible. Does the surface topography explain chemiexcitation yield differences?

scholarly journals Role of conical intersection seam topography in the chemiexcitation of 1,2-dioxetanes

2021 ◽  
Author(s):  
Ignacio Fernández Galván ◽  
Anders Brakestad ◽  
Morgane Vacher
Keyword(s):  
Excited States ◽  
Ground State ◽  
Potential Energy Surfaces ◽  
Thermal Reaction ◽  
Conical Intersection ◽  
Conical Intersections ◽  
Nonadiabatic Transition ◽  
Isolated Points ◽  
Energy Surfaces

Chemiexcitation, the generation of electronic excited states by a thermal reaction initiated on the ground state, is an essential step in chemiluminescence, and it is mediated by the presence of a conical intersection that allows a nonadiabatic transition from ground state to excited state. Conical intersections classified as sloped favor chemiexcitation over ground state relaxation. The chemiexcitation yield of 1,2-dioxetanes is known to increase upon methylation. In this work we explore to which extent this trend can be attributed to changes in the conical intersection topography or accessibility. Since conical intersections are not isolated points, but continuous seams, we locate regions of the conical intersection seams that are close to the configuration space traversed by the molecules as they react on the ground state. We find that conical intersections are energetically and geometrically accessible from the reaction trajectory, and that topographies favorable to chemiexcitation are found in all three molecules studied. Nevertheless, the results suggest that dynamic effects are more important for explaining the different yields than the static features of the potential energy surfaces.

The role of zero-field splitting and π-stacking interaction of different nitrogen-donor ligands on the optical properties of luminescent rhenium tricarbonyl complexes

2021 ◽  
Author(s):  
Plinio Cantero-López ◽  
Yoan Hidalgo-Rosa ◽  
Zoraida Sandoval-Olivares ◽  
Julián Santoyo-Flores ◽  
Pablo Mella ◽  
...  
Keyword(s):  
Excited States ◽  
Coordination Compounds ◽  
Donor Ligands ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Nitrogen Donor Ligands ◽  
Nitrogen Donor ◽  
Π Stacking Interaction ◽  
Rhenium Tricarbonyl

Rhenium tricarbonyl complexes are one of the most important classes of coordination compounds in inorganic chemistry. Exploring their luminescent excited states, lowest singlet (S1), and the lowest triplet (T1), is...

scholarly journals Influence of TOPO and TOPO-CdSe/ZnS Quantum Dots on Luminescence Photodynamics of InP/InAsP/InPHeterostructure Nanowires

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 640
Author(s):  
Artem I. Khrebtov ◽  
Vladimir V. Danilov ◽  
Anastasia S. Kulagina ◽  
Rodion R. Reznik ◽  
Ivan D. Skurlov ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Excited States ◽  
Molecular Beam ◽  
Surface Passivation ◽  
Low Energy ◽  
Trioctylphosphine Oxide ◽  
Reverse Transfer ◽  
Semiconductor Heterostructure ◽  
Ligand Type

The passivation influence by ligands coverage with trioctylphosphine oxide (TOPO) and TOPO including colloidal CdSe/ZnS quantum dots (QDs) on optical properties of the semiconductor heterostructure, namely an array of InP nanowires (NWs) with InAsP nanoinsertion grown by Au-assisted molecular beam epitaxy on Si (111) substrates, was investigated. A significant dependence of the photoluminescence (PL) dynamics of the InAsP insertions on the ligand type was shown, which was associated with the changes in the excitation translation channels in the heterostructure. This change was caused by a different interaction of the ligand shells with the surface of InP NWs, which led to the formation of different interfacial low-energy states at the NW-ligand boundary, such as surface-localized antibonding orbitals and hybridized states that were energetically close to the radiating state and participate in the transfer of excitation. It was shown that the quenching of excited states associated with the capture of excitation to interfacial low-energy traps was compensated by the increasing role of the “reverse transfer” mechanism. As a result, the effectiveness of TOPO-CdSe/ZnS QDs as a novel surface passivation coating was demonstrated.

The role of surface topography and normal load in the initiation of ratchetting-peak friction, seizure, scuffing, and elastic shakedown

2021 ◽  
pp. 1-12
Author(s):  
Vimal Edachery ◽  
V. Swamybabu ◽  
Gurupatham Anand ◽  
Paramasamy Manikandan ◽  
Satish V. Kailas
Keyword(s):  
Steady State ◽  
Surface Topography ◽  
Sliding Wear ◽  
Friction And Wear ◽  
Critical Parameter ◽  
Normal Load ◽  
Sliding Direction ◽  
Elastic Shakedown ◽  
Lubrication Conditions

Abstract Surface topography is a critical parameter that can influence friction and wear in engineering applications. In this work, the influence of surface topography directionality on seizure and scuffing initiation during tribological interactions is explored. For this, unidirectional sliding wear experiments were carried out in immersed lubrication conditions for various normal loads. The tribological interactions were studied using EN31-60 HRC flats and SAE52100-60HRC pins in a sphere on flat configuration. The results show that, in some cases, the sliding interactions in the initial cycles lead to a high friction coefficient of up to ∼0.68 in lubricated conditions, which was termed as ‘peak friction’, and this was accompanied by scuffing. The existence of peak friction was found to be dependent on surface topography directionality, especially when the directionality in topography was parallel to the sliding direction. Continuous ratchetting was found to be the cause of peak friction which was accompanied by seizure and scuffing. When the topography directionality was perpendicular or independent of sliding direction, elastic shakedown occurred at earlier cycles and prevented peak friction initiation, scuffing and also facilitated for higher steady-state friction values.

Erratum: Role of excited states in multiphoton dynamics

1989 ◽  
Vol 39 (3) ◽  
pp. 1570-1570
Author(s):  
Bala Sundaram ◽  
Lloyd Armstrong
Keyword(s):  
Excited States
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