scholarly journals Quantum Control of Coherent π-Electron Dynamics in Aromatic Ring Molecules

2021 ◽  
Vol 9 ◽  
Author(s):  
Hirobumi Mineo ◽  
Ngoc-Loan Phan ◽  
Yuichi Fujimura
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Aromatic Ring ◽  
Excited States ◽  
Quantum Control ◽  
Ring Current ◽  
Theoretical Description ◽  
Electron Dynamics ◽  
Ring Molecules ◽  
Electron Ring

Herein we review a theoretical study of unidirectional π-electron rotation in aromatic ring molecules, which originates from two quasi-degenerate electronic excited states created coherently by a linearly polarized ultraviolet/visible laser with a properly designed photon polarization direction. Analytical expressions for coherent π-electron angular momentum, ring current and ring current-induced magnetic field are derived in the quantum chemical molecular orbital (MO) theory. The time evolution of the angular momentum and the ring current are expressed using the density matrix method under Markov approximation or by solving the time-dependent Schrödinger equation. In this review we present the results of the following quantum control scenarios after a fundamental theoretical description of coherent angular momentum, ring current and magnetic field: first, two-dimensional coherent π-electron dynamics in a non-planar (P)-2,2’-biphenol molecule; second, localization of the coherent π-electron ring current to a designated benzene ring in polycyclic aromatic hydrocarbons; third, unidirectional π-electron rotations in low-symmetry aromatic ring molecules based on the dynamic Stark shift of two relevant excited states that form a degenerate state using the non-resonant ultraviolet lasers. The magnetic fields induced by the coherent π-electron ring currents are also estimated, and the position dependence of the magnetic fluxes is demonstrated.

The generation of stationary π-electron rotations in chiral aromatic ring molecules possessing non-degenerate excited states

2016 ◽  
Vol 18 (3) ◽  
pp. 1570-1577 ◽  
Author(s):  
Masahiro Yamaki ◽  
Yoshiaki Teranishi ◽  
Hiroki Nakamura ◽  
Sheng Hsien Lin ◽  
Yuichi Fujimura
Keyword(s):  
Angular Momentum ◽  
Aromatic Ring ◽  
Excited States ◽  
High Symmetry ◽  
Laser Fields ◽  
Ring Molecules ◽  
Fundamental Quantity ◽  
Low Symmetry

Stationary angular momentum, which is a fundamental quantity of high-symmetry aromatic ring molecules, can be created for low-symmetry ring molecules by applying theoretically designed stationary laser fields.

scholarly journals DOUBLE-VALUEDNESS OF THE ELECTRON WAVEFUNCTION AND ROTATIONAL ZERO-POINT MOTION OF ELECTRONS IN RINGS

2010 ◽  
Vol 24 (21) ◽  
pp. 2201-2214 ◽  
Author(s):  
J. E. HIRSCH
Keyword(s):  
Angular Momentum ◽  
Aromatic Ring ◽  
Orbital Angular Momentum ◽  
Ground State ◽  
Spin Current ◽  
Zero Point ◽  
Persistent Currents ◽  
Ring Molecules ◽  
Point Motion ◽  
Electron Wavefunction

I propose that the phase of an electron's wavefunction changes by π when the electron goes around a loop maintaining phase coherence. Equivalently, that the minimum orbital angular momentum of an electron in a ring is ℏ/2 rather than zero as generally assumed, hence, that the electron in a ring has azimuthal zero point motion. This proposal implies that a spin current exists in the ground state of aromatic ring molecules and suggests an explanation for the ubiquitousness of persistent currents observed in mesoscopic rings.

Induction of unidirectional π-electron rotations in low-symmetry aromatic ring molecules using two linearly polarized stationary lasers

2016 ◽  
Vol 18 (38) ◽  
pp. 26786-26795 ◽  
Author(s):  
Hirobumi Mineo ◽  
Masahiro Yamaki ◽  
Gap-Sue Kim ◽  
Yoshiaki Teranishi ◽  
Sheng Hsien Lin ◽  
...  
Keyword(s):  
Aromatic Ring ◽  
Excited States ◽  
Ring Molecules ◽  
Linearly Polarized ◽  
Laser Control ◽  
Low Symmetry

A new laser-control scenario of unidirectional π-electron rotations in an aromatic ring molecule having no degenerate excited states is proposed.

The Rotational Zeeman Effect of Pyrazole and Imidazole

1987 ◽  
Vol 42 (1) ◽  
pp. 49-56 ◽  
Author(s):  
M. Stolze ◽  
D. H. Sutter
Keyword(s):  
Magnetic Susceptibility ◽  
Angular Momentum ◽  
Ring Current ◽  
Zeeman Effect ◽  
Membered Ring ◽  
Ring Molecules ◽  
Isotopic Species ◽  
Out Of Plane ◽  
Additivity Rules ◽  
Single Standard

The rotational Zeeman effect of the most abundant isotopic species of pyrazole and of imidazole has been studied under Δ M= 0 and Δ M = ± 1 selection rules. With field close to 1.9 Tesla, the nuclear Zeeman effect uncouples the rotational angular momentum and the spins of the two nonequivalent 14N quadrupole nuclei. The observed g-tensor elements are gaa = - 0.07498(14), gbb = - 0.12531(13), and gcc = 0.06346(12) for pyrazole and gaa = - 0.09339(16), gbb = - 0.10444(14), and gcc= 0.06051(15) for imidazole. The values for the magnetic susceptibility anisotropies in units of 10-6 erg/(G2 mol) are 2Xaa - Xbb - Xcc = 39.53(24) and 2Xbb - Xcc - Xaa = 51.20(21) for pyrazole and 2xaa - Xbb - Xcc = 45.76(31) and 2Xbb - Xcc - Xaa = 42.19(41) for imidazole. (Given uncertainties are single standard deviations of the fit.) The so-called nonlocal (π-ring current) contributions to the out of plane components of the susceptibility tensor Xccnonlocal, derived as differences between the observed susceptibilities and values calculated from additivity rules for local atom susceptibilities, are compared to those derived earlier for other aromatic five membered ring molecules.

scholarly journals Laser-Control of Ultrafast π-Electron Ring Currents in Aromatic Molecules: Roles of Molecular Symmetry and Light Polarization

2018 ◽  
Vol 8 (12) ◽  
pp. 2347 ◽  
Author(s):  
Manabu Kanno ◽  
Hirohiko Kono ◽  
Yuichi Fujimura
Keyword(s):  
Angular Momentum ◽  
Optical Switching ◽  
Ring Current ◽  
Molecular Vibration ◽  
Vibrational Amplitude ◽  
Electron Dynamics ◽  
Aromatic Molecules ◽  
Ring Currents ◽  
Laser Control ◽  
Ultrafast Electron Dynamics

Being motivated by the recent progress in attosecond laser technology, we theoretically explore the strategy of inducing ultrafast electron dynamics inherent to aromatic molecules, i.e., ring currents by means of polarized laser pulses. The main topic of discussion is how to control the direction of ring currents in an aromatic molecule of low symmetry, for which the design of an efficient control pulse cannot be achieved intuitively. We first consider a system with a single aromatic ring and show that coherent π-electron angular momentum, which oscillates with time, can be produced and controlled by a polarized laser pulse with its ellipticity and orientation properly chosen. Nonadiabatic couplings with molecular vibration gradually weaken the angular momentum, while the vibrational amplitude strongly depends on the polarization of incident light. This suggests the conversion of the polarization dependence of ring current into that of subsequent vibration, which may open a way to detect laser-driven ultrafast electron dynamics by vibrational spectroscopy. The laser-control scheme for the ring current is then extended to a molecule with two aromatic rings, which exhibits characteristic phenomena absent in that with a single ring. We demonstrate that two-dimensional switching of the direction of angular momentum is possible in such molecules. In addition, ring current can be localized at a specific ring by tailored lasers. The application of the present control method to polycyclic aromatic hydrocarbons will lead to the development of next-generation organic optical switching devices.

scholarly journals Study of relativistic magnetized outflows with relativistic equation of state

2019 ◽  
Vol 488 (4) ◽  
pp. 5713-5727
Author(s):  
Kuldeep Singh ◽  
Indranil Chattopadhyay
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Equation Of State ◽  
Polar Angle ◽  
Relativistic Equation ◽  
Azimuthal Velocity ◽  
Astrophysical Jets ◽  
Composition Parameter ◽  
Field Lines ◽  
Flow Experiences

ABSTRACT We study relativistic magnetized outflows using relativistic equation of state having variable adiabatic index (Γ) and composition parameter (ξ). We study the outflow in special relativistic magnetohydrodynamic regime, from sub-Alfvénic to super-fast domain. We showed that, after the solution crosses the fast point, magnetic field collimates the flow and may form a collimation-shock due to magnetic field pinching/squeezing. Such fast, collimated outflows may be considered as astrophysical jets. Depending on parameters, the terminal Lorentz factors of an electron–proton outflow can comfortably exceed few tens. We showed that due to the transfer of angular momentum from the field to the matter, the azimuthal velocity of the outflow may flip sign. We also study the effect of composition (ξ) on such magnetized outflows. We showed that relativistic outflows are affected by the location of the Alfvén point, the polar angle at the Alfvén point and also the angle subtended by the field lines with the equatorial plane, but also on the composition of the flow. The pair dominated flow experiences impressive acceleration and is hotter than electron–proton flow.

scholarly journals Analytical Theory of Attosecond Transient Absorption Spectroscopy of Perturbatively Dressed Systems

2019 ◽  
Vol 9 (7) ◽  
pp. 1350
Author(s):  
Daria Kolbasova ◽  
Robin Santra
Keyword(s):  
Perturbation Theory ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Electronic States ◽  
Theoretical Description ◽  
Transient Absorption Spectroscopy ◽  
Electron Dynamics ◽  
Optical Pulses ◽  
Absorption Signal ◽  
Level Model

A theoretical description of attosecond transient absorption spectroscopy for temporally and spatially overlapping XUV and optical pulses is developed, explaining the signals one can obtain in such an experiment. To this end, we employ a two-stage approach based on perturbation theory, which allows us to give an analytical expression for the transient absorption signal. We focus on the situation in which the attosecond XUV pulse is used to create a coherent superposition of electronic states. As we explain, the resulting dynamics can be detected in the spectrum of the transmitted XUV pulse by manipulating the electronic wave packet using a carrier-envelope-phase-stabilized optical dressing pulse. In addition to coherent electron dynamics triggered by the attosecond pulse, the transmitted XUV spectrum encodes information on electronic states made accessible by the optical dressing pulse. We illustrate these concepts through calculations performed for a few-level model.

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