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 tunneling model of ionization applies only to longitudinal fields:quasistatic electric fields that do not propagate. Laser fields are transverse:plane wave fields that possess the ability to propagate. Although there is anapproximate connection between the effects of longitudinal and transversefields in a useful range of frequencies, that equivalence fails completely atvery low frequencies. Insight into this breakdown is given by an examination ofradiation pressure, which is a unique transverse-field effect whose relativeimportance increases rapidly as the frequency declines. Radiation pressure canbe ascribed to photon momentum, which does not exist for longitudinal fields.Two major consequences are that the near-universal acceptance of a staticelectric field as the zero frequency limit of a laser field is not correct; andthat the numerical solution of the dipole-approximate Schr\"{o}dinger equationfor laser effects is inapplicable as the frequency declines. These problemsoccur because the magnetic component of the laser field is very important atlow frequencies, and hence the dipole approximation is not valid. Someexperiments already exist that demonstrate the failure of tunneling concepts atlow frequencies.

The tunneling model of laser-induced ionization and its failure at low frequencies