English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The Raman selection rules arise from the crystal symmetry and then determinethe Raman activity and polarization of scattered phonon modes. However, theseselection rules can be broken in resonant process due to the strongelectron-phonon coupling effect. Here we reported the observation of breakdownof Raman selection rules in few-layer WS$_2$ by using resonant Raman scatteringwith dark A exciton. In this case, not only the infrared active modes andbackscattering forbidden modes are observed, but the intensities of allobserved phonon modes become strongest under paralleled-polarization andindependent on the Raman tensors of phonons. We attributed this phenomenon tothe interaction between dark A exciton and the scatted phonon, the so-calledintraband Fr\"{o}hlich interaction, where the Raman scattering possibility istotally determined by the symmetry of exciton rather than the phonons due tostrong electron-phonon coupling. Our results not only can be used to easilydetect the optical forbidden excitonic and phononic states but also provide apossible way to manipulate optical transitions between electronic levels.

Breakdown of Raman Selection Rules By Fr\"{o}hlich Interaction in Few-Layer WS$_2$