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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

A new collection of photodissociation and photoionisation cross sections for102 atoms and molecules of astrochemical interest has been assembled, alongwith a brief review of the basic processes involved. These have been used tocalculate dissociation and ionisation rates, with uncertainties, in a standardultraviolet interstellar radiation field (ISRF) and wavelength-dependentradiation fields. The new ISRF rates generally agree within 30% with ourprevious compilations, with a few notable exceptions. The reduction of rates inshielded regions was calculated as a function of dust, molecular and atomichydrogen, atomic C, and self-shielding column densities. The relativeimportance of shielding types depends on the species in question and the dustoptical properties. The new data are publicly available from the Leidenphotodissociation and ionisation database.  Sensitivity of rates to variation of temperature and isotope, and crosssection uncertainties, are tested. Tests were conducted with aninterstellar-cloud chemical model, and find general agreement (within a factorof two) with the previous iteration of the Leiden database for the ISRF, andorder-of-magnitude variations assuming various kinds of stellar radiation. Thenewly parameterised dust-shielding factors makes a factor-of-two difference tomany atomic and molecular abundances relative to parameters currently in theUDfA and KIDA astrochemical reaction databases. The newly-calculated cosmic-rayinduced photodissociation and ionisation rates differ from current standardvalues up to a factor of 5. Under high temperature and cosmic-ray-fluxconditions the new rates alter the equilibrium abundances of abundant darkcloud abundances by up to a factor of two. The partial cross sections for H2Oand NH3 photodissociation forming OH, O, NH2 and NH are also evaluated and leadto radiation-field-dependent branching ratios.

Photodissociation and photoionisation of atoms and molecules of astrophysical interest