Synopsis

Hot currents in benzene

Physics 3, s37
Simulations reveal how laser-excited persistent currents in ring-shaped aromatic molecules couple to vibrational modes.

Laser pulses of circularly polarized light can drive π electrons around the ring of an aromatic molecule. For example, photoexcited π-electron currents flow around a benzene ring formed by the hexagonal carbon-atom structure. Theoretical studies of such systems are promising, but they are limited to zero-temperature applications because they assume rigid molecules at rest.

Writing in Physical Review Letters, Manabu Kanno, Hirohiko Kono, and Yuichi Fujimura at Tokohu University, Japan, and Sheng H. Lin at Academia Sinica in Taiwan report a simulation of the interaction between photoexcited ring currents and vibrational atomic modes in an aromatic molecule ( 2,5-dichloropyrazine), which has characteristics of a chiral molecule. For such a molecule, currents can be created by linearly polarized light. Atoms in the molecule are found to vibrate with amplitudes that are sensitive to the direction of flow of the ring currents. This directional coupling allows the authors to propose detecting the switching behavior of π-electron currents by monitoring the vibrational modes of the molecule.

Thermal fluctuations are not included in the simulations, but the coupling to vibrational modes suggests that photoexcited currents might be stable enough for high-temperature applications. The optical control of currents at accessible temperatures could open the door to a host of future molecular devices. Similar to supercurrents that flow in superconducting quantum interference devices (SQUIDs), molecular ring currents could be used in molecular detectors of localized magnetic flux at high temperatures. – Saad Hebboul

Correction (23 March 2010): Paragraph 2, sentences 1 and 2, ”…vibrational atomic modes in a chiral aromatic molecule ( 2,5-dichloropyrazine). For a chiral aromatic molecule…” changed to ”…vibrational atomic modes in an aromatic molecule ( 2,5-dichloropyrazine), which has characteristics of a chiral molecule. For such a molecule…”


Subject Areas

OpticsChemical Physics

Related Articles

Microwaves Can Suppress Chemical Reactions
Chemical Physics

Microwaves Can Suppress Chemical Reactions

The heating effect of microwaves has long been used to accelerate reactions. A new experiment shows that microwaves can also excite molecules into a less reactive state. Read More »

Birefringent Nanocubes Give Light a Circular Boost
Optics

Birefringent Nanocubes Give Light a Circular Boost

An achiral metasurface selectively transmits two beams of opposite chirality. Read More »

Gauging the Temperature Sensitivity of a Nuclear Clock
Atomic and Molecular Physics

Gauging the Temperature Sensitivity of a Nuclear Clock

Researchers have characterized the temperature-induced frequency shifts of a thorium-229 nuclear transition—an important step in establishing thorium clocks as next-generation frequency standards. Read More »

More Articles