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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The impulsive limit (the "sudden approximation") has been widely employed todescribe the interaction between molecules and short, far-off-resonant laserpulses. This approximation assumes that the timescale of the laser--moleculeinteraction is significantly shorter than the internal rotational period of themolecule, resulting in the rotational motion being instantaneously "frozen"during the interaction. This simplified description of laser-moleculeinteraction is incorporated in various theoretical models predicting rotationaldynamics of molecules driven by short laser pulses. In this theoretical work,we develop an effective theory for ultrashort laser pulses by examining thefull time-evolution operator and solving the time-dependent Schr\"odingerequation at the operator level. Our findings reveal a critical angularmomentum, $l_\mathrm{crit}$, at which the impulsive limit breaks down. In otherwords, the validity of the sudden approximation depends not only on the pulseduration, but also on its intensity, since the latter determines how manyangular momentum states are populated. We explore both ultrashort multi-cycle(Gaussian) pulses and the somewhat less studied half-cycle pulses, whichproduce distinct effective potentials. We discuss the limitations of theimpulsive limit and propose a new method that rescales the effective matrixelements, enabling an improved and more accurate description of laser-moleculeinteractions.

Modeling laser pulses as $\delta$-kicks: reevaluating the impulsive limit in molecular rotational dynamics