2 research outputs found
Quantum Switching of π‑Electron Rotations in a Nonplanar Chiral Molecule by Using Linearly Polarized UV Laser Pulses
Nonplanar chiral aromatic molecules are candidates for
use as building
blocks of multidimensional switching devices because the π electrons
can generate ring currents with a variety of directions. We employed
(<i>P</i>)-2,2′-biphenol because four patterns of
Ï€-electron rotations along the two phenol rings are possible
and theoretically determine how quantum switching of the π-electron
rotations can be realized. We found that each rotational pattern can
be driven by a coherent excitation of two electronic states under
two conditions: one is the symmetry of the electronic states and the
other is their relative phase. On the basis of the results of quantum
dynamics simulations, we propose a quantum control method for sequential
switching among the four rotational patterns that can be performed
by using ultrashort overlapped pump and dump pulses with properly
selected relative phases and photon polarization directions. The results
serve as a theoretical basis for the design of confined ultrafast
switching of ring currents of nonplanar molecules and further current-induced
magnetic fluxes of more sophisticated systems
Quantum Localization of Coherent π‑Electron Angular Momentum in (<i>P</i>)‑2,2′-Biphenol
Controlling
Ï€-electrons with delocalized character is one
of the fundamental issues in femtosecond and attosecond chemistry.
Localization of π-electron rotation by using laser pulses is
expected to play an essential role in nanoscience. The π-electron
rotation created at a selected aromatic ring of a single molecule
induces a local intense electromagnetic field, which is a new type
of ultrafast optical control functioning. We propose a quantum localization
of coherent π-electron angular momentum in (<i>P</i>)-2,2′-biphenol, which is a simple, covalently linked chiral
aromatic ring chain molecule. The localization considered here consists
of sequential two steps: the first step is to localize the π-electron
angular momentum at a selected ring of the two benzene rings, and
the other is to maintain the localization. Optimal control theory
was used for obtaining the optimized electric fields of linearly polarized
laser pulses to realize the localization. The optimal electric fields
and the resultant coherent electronic dynamics are analyzed