scholarly journals From Symmetry Breaking via Charge Migration to Symmetry Restoration in Electronic Ground and Excited States: Quantum Control on the Attosecond Time Scale

2019 ◽  
Vol 9 (5) ◽  
pp. 953 ◽  
Author(s):  
ChunMei Liu ◽  
Joern Manz ◽  
Jean Christophe Tremblay
Keyword(s):  
Excited States ◽  
Ground State ◽  
Quantum Dynamics ◽  
Quantum Control ◽  
Laser Pulses ◽  
Dynamics Simulation ◽  
Superposition State ◽  
Charge Migration ◽  
Time Domains ◽  
Electronic Ground

This article starts with an introductory survey of previous work on breaking and restoringthe electronic structure symmetry of atoms and molecules by means of two laser pulses. Accordingly,the first pulse breaks the symmetry of the system in its ground state with irreducible representationIRREPg by exciting it to a superposition of the ground state and an excited state with differentIRREPe. The superposition state is non-stationary, representing charge migration with period T inthe sub- to few femtosecond time domains. The second pulse stops charge migration and restoressymmetry by de-exciting the superposition state back to the ground state. Here, we present a newstrategy for symmetry restoration: The second laser pulse excites the superposition state to the excitedstate, which has the same symmetry as the ground state, but different IRREPe. The success dependson perfect time delay between the laser pulses, with precision of few attoseconds. The new strategyis demonstrated by quantum dynamics simulation for an oriented model system, benzene.

scholarly journals Mechanisms of Laser-Induced Reactions of Stacked Benzene Molecules: A Semiclassical Dynamics Simulation and CASSCF Calculation

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Kunxian Shu ◽  
Jie Zhao ◽  
Shuai Yuan ◽  
Yusheng Dou ◽  
Glenn V. Lo
Keyword(s):  
Ground State ◽  
Bond Cleavage ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Dynamics Simulation ◽  
Covalent Bonds ◽  
Semiclassical Dynamics ◽  
Ultrashort Laser ◽  
Electronic Ground ◽  
Casscf Calculation

The response to ultrashort laser pulses of two stacked benzene molecules has been studied by semiclassical dynamics simulation; two typical pathways were found following excitation of one of the benzene molecules by a 25 fs (FWHM), 4.7 eV photon. With a fluence of 40.49 J/m2, the stacked molecules form a cyclobutane benzene dimer; the formation of the two covalent bonds linking two benzenes occurs asynchronously after the excimer decays to electronic ground state. With a fluence of 43.26 J/m2, only one bond is formed, which breaks about 50 fs after formation, followed by separation into the two molecules. The deformation of benzene ring is found to play an important role in the bond cleavage.

scholarly journals Electron Symmetry Breaking during Attosecond Charge Migration Induced by Laser Pulses: Point Group Analyses for Quantum Dynamics

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 205
Author(s):  
Dietrich Haase ◽  
Gunter Hermann ◽  
Jörn Manz ◽  
Vincent Pohl ◽  
Jean Christophe Tremblay
Keyword(s):  
Laser Pulse ◽  
Symmetry Breaking ◽  
Electric Fields ◽  
Quantum Dynamics ◽  
Point Group ◽  
Laser Pulses ◽  
Charge Migration ◽  
Laser Control ◽  
The One ◽  
Superposition States

Quantum simulations of the electron dynamics of oriented benzene and Mg-porphyrin driven by short (<10 fs) laser pulses yield electron symmetry breaking during attosecond charge migration. Nuclear motions are negligible on this time domain, i.e., the point group symmetries G = D6h and D4h of the nuclear scaffolds are conserved. At the same time, the symmetries of the one-electron densities are broken, however, to specific subgroups of G for the excited superposition states. These subgroups depend on the polarization and on the electric fields of the laser pulses. They can be determined either by inspection of the symmetry elements of the one-electron density which represents charge migration after the laser pulse, or by a new and more efficient group-theoretical approach. The results agree perfectly with each other. They suggest laser control of symmetry breaking. The choice of the target subgroup is restricted, however, by a new theorem, i.e., it must contain the symmetry group of the time-dependent electronic Hamiltonian of the oriented molecule interacting with the laser pulse(s). This theorem can also be applied to confirm or to falsify complementary suggestions of electron symmetry breaking by laser pulses.

scholarly journals Photophysics of a copper phenanthroline elucidated by trajectory and wavepacket-based quantum dynamics: a synergetic approach

2017 ◽  
Vol 19 (30) ◽  
pp. 19590-19600 ◽  
Author(s):  
G. Capano ◽  
T. J. Penfold ◽  
M. Chergui ◽  
I. Tavernelli
Keyword(s):  
Molecular Dynamics ◽  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Quantum Dynamics ◽  
Equilibrium Processes ◽  
Valuable Method ◽  
Non Equilibrium

On-the-fly excited state molecular dynamics is a valuable method for studying non-equilibrium processes in excited states and is beginning to emerge as a mature approach much like its ground state counterparts.

Controlled intramolecular H-transfer in malonaldehyde in the electronic ground state mediated through the conical intersection of 1nπ* and 1ππ* excited electronic states

2019 ◽  
Vol 21 (36) ◽  
pp. 20018-20030 ◽  
Author(s):  
K. R. Nandipati ◽  
Arun Kumar Kanakati ◽  
H. Singh ◽  
S. Mahapatra
Keyword(s):  
Ground State ◽  
Electronic States ◽  
Laser Pulses ◽  
Electronic Ground State ◽  
Conical Intersection ◽  
Uv Laser ◽  
Excited Electronic States ◽  
Electronic Ground

We report photo-isomerization of malonaldehyde in its electronic ground state (S0), mediated by coupled 1nπ*(S1)–1ππ*(S2) excited electronic states, accomplished with the aid of optimally designed ultraviolet (UV)-laser pulses.

Theoretical Study of the Dissociation and Isomerization of NCS

2003 ◽  
Vol 217 (3) ◽  
pp. 255-264 ◽  
Author(s):  
M. Diehr ◽  
G. Chambaud ◽  
H.-J. Werner
Keyword(s):  
Excited States ◽  
Dissociation Energy ◽  
Ground State ◽  
Spectroscopic Data ◽  
Large Scale ◽  
Theoretical Study ◽  
Ground States ◽  
Electronic Ground State ◽  
Barrier Heights ◽  
Electronic Ground

AbstractLarge scale MRCI calculations have been performed to study the electronic ground state and low-lying excited states of the NCS molecule and its isomers. The isomer CNS is found to be stable and linear. It lies 1.29 eV higher in energy than NCS, while CSN has a much higher energy and is unstable. The dissociation energy of the NCS isomer has been calculated to be 4.25 eV. The isomerization paths between the 2Π ground states of both isomers have been mapped by CASSCF and MRCI calculations. The barriers for the NCS → CNS isomerization in 2A′ and 2A″ symmetry have cyclic forms and the barrier heights have been calculated to be 2.71 eV and 2.44 eV, respectively (MRCI). For both isomers, the collinear dissociation paths to the (diatomic + atom) fragments have been investigated by CASSCF calculations. Spectroscopic data are given for the X2Π ground state and for the A2Σ+ state of CNS. The results are compared with the valence isoelectronic system NCO.

Is it really possible to control aromaticity of benzene with light?

2020 ◽  
Vol 22 (27) ◽  
pp. 15401-15412
Author(s):  
F. Bouakline ◽  
J. C. Tremblay
Keyword(s):  
Excited States ◽  
Ground State ◽  
Laser Pulses ◽  
Theoretical Investigations

We question the findings of recent theoretical investigations, which claim that tailored laser pulses may selectively steer benzene's aromatic ground state to localized non-aromatic excited states.

Quantum dynamics of H+LiH+ reaction on its electronic ground state

2011 ◽  
Vol 501 (4-6) ◽  
pp. 252-256 ◽  
Author(s):  
Tanmoy Roy ◽  
T. Rajagopala Rao ◽  
S. Mahapatra
Keyword(s):  
Ground State ◽  
Quantum Dynamics ◽  
Electronic Ground State ◽  
Electronic Ground

scholarly journals All-optical control of pendular qubit states with nonresonant two-color laser pulses.

2021 ◽  
Author(s):  
Je Hoi Mun ◽  
Minemoto Shinichirou ◽  
Dong Eon Kim ◽  
Hirofumi Sakai
Keyword(s):  
Quantum State ◽  
Ground State ◽  
Quantum Control ◽  
Coherent Control ◽  
Control Method ◽  
Laser Pulses ◽  
Velocity Map Imaging ◽  
Peak Intensity ◽  
New Type ◽  
Omega Laser

Abstract Practical methodologies for quantum qubit controls are established by two prerequisites, i.e., preparation of a well-defined initial quantum state and coherent control of that quantum state. Here we propose a new type of quantum control method, realized by irradiating nonresonant nanosecond two-color ($\omega$ and 2$\omega$) laser pulses to molecules in the pendular (field-dressed) ground state. The two-color field nonadiabatically splits the initial pendular ground state $\vert\tilde{0},\tilde{0}\rangle$ to a superposition state of $\vert\tilde{0},\tilde{0}\rangle$ and $\vert\tilde{1},\tilde{0}\rangle$, whose relative probability amplitudes can be controlled by the peak intensity of one wavelength component ($\omega$) while the peak intensity of the other component (2$\omega$) is fixed. The splitting of the quantum paths is evidenced by observing degrees of orientation of ground-state-selected OCS molecules by the velocity map imaging technique. This quantum control method is highly advantageous in that any type of polar molecules can be controlled regardless of the molecular parameters, such as rotational energy, permanent dipole moment, polarizability, hyperpolarizability, and hyperfine energy structures.

Nonlinear excitation and ionization of diatomic molecules by short laser pulses. Model of two active electrons in the field of a frozen core

2002 ◽  
Vol 80 (2) ◽  
pp. 149-171
Author(s):  
A I Pegarkov
Keyword(s):  
Ground State ◽  
Diatomic Molecules ◽  
Laser Pulses ◽  
Electron Excitation ◽  
Quantum Mechanical ◽  
Electron Dynamics ◽  
Nonlinear Excitation ◽  
Fs Laser ◽  
Short Laser Pulses ◽  
Electronic Ground

The dynamics of electron excitation and ionization of diatomic molecules in short laser pulses is studied within a model of two active 1D electrons moving in the field of a frozen core. It is shown for example for the N2 molecule that the model reproduces the spectrum of the pulse-free Σ electronic states very well. The N2 electron dynamics is examined numerically for short τ = 30 fs and ultra-short τ = 5 fs laser pulses with λ = 800 nm and intensity 1013 W/cm2 ÷ 1015 W/cm2 as well as for the resonant pulse with τ = 1 fs and λ = 147 nm, 1014 W/cm2 ÷ 1016 W/cm2. The phenomena of strong above-threshold absorption and resonant revival of electronic ground-state population in the ultra-short resonant pulse are found. Within the model, the quantum-mechanical picture of one-electron, two-electron, sequential, and nonsequential molecular ionizations is analyzed in detail in comparison with recent experimental results of Cornaggia and Hering, and Gibson et al. The model correctly explains the origin and nonlinear dynamics of the well-known "shoulder" in the N2+2 ion yield. PACS Nos.: 33.80Rv, 33.80Wz

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