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/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Using a spatially filtered pulsed laser at 486 nm we have photoexcited positronium to the 2S state and detected it via a delayed and spatially separated 532-nm photoionization pulse. We have extended our observations down to low 486-nm power to explore the possibility of a cw measurement of the positronium 1S-2S interval. A model calculation taking into account the velocity distribution of the 235-K positronium from an oxygenated cold Al(111) target, the parameters of the laser beams, and the nonlinear excitation probability explains our data. The same model indicates that a cw measurement is presently feasible

Sensitive detection of Doppler-free two-photon-excited 2Spositronium by spatially separated photoionization