THE CHEMISTRY OF INTERSTELLAR MOLECULES CONTAINING THE HALOGEN ELEMENTS

摘要: Although they are only minor constituents of the interstellar medium, halogen-containing molecules special interest because their unique thermochemistry. Here, we present a theoretical study chemistry containing halogen elements chlorine and fluorine. We have modeled both diffuse dense molecular clouds, making use updated estimates for rates several key chemical processes. predictions abundances three that been detected to date in medium: HF, CF+, HCl. As our previous fluorine-bearing molecules, predict HF be dominant gas-phase reservoir fluorine within clouds; expect Herschel Space Observatory detect widespread absorption J = 1 – 0 transition. Our model now overpredicts CF+ abundance by factor 10 relative observations Orion Bar; this discrepancy has widened adopt laboratory measurement dissociative recombination rate is smaller than estimate adopted previously. This disagreement suggests reaction C+ with proceeds more slowly capture assumed model; would very desirable. predicts cloud HCl similar those predicted previously tentatively toward ζ Oph. Two additional species potentially detectable from photodissociation regions: H2Cl+, HCl+ ions. Ortho-H2Cl+ its lowest-lying transition millimeter spectral region observable ground, lowest rotational Herschel's HIFI instrument.