Eur. Phys. J. D (2015) 69: 84
https://doi.org/10.1140/epjd/e2015-50721-8

Regular Article

Electron-induced ionization and dissociative ionization of iron pentacarbonyl molecules^*

¹ Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynska dolina, 84248 Bratislava, Slovakia
² Department of Chemistry, Siedlce University, 3 Maja 54, 08-110 Siedlce, Poland

^a e-mail: papp@fmph.uniba.sk

Received: 30 September 2014
Received in final form: 30 December 2014
Published online: 24 March 2015

Abstract

Electron ionization (EI) and dissociative ionization (DI) of Iron pentacarbonyl molecule (Fe(CO)₅) was studied using a crossed molecular and electron beam mass spectrometry technique. Positive ions FeO(CO)⁺, FeC(CO)²⁺ and CO⁺ of Fe(CO)₅ were detected for the first time. We have determined the experimental appearance energies of positive ions, the thresholds for dissociative reactions, the experimental bond dissociation energies for (CO)_nFe⁺-CO bond breaks (for n = 4,..., 0) and their average value for Fe-C bond energy 1.25 eV in Fe(CO)₅⁺. We have performed extensive density functional theory (DFT) studies of the ground states of neutral molecule and fragments ¹ A₁^' Fe(CO)₅, ³B₁ Fe(CO)₄, ³A₁Fe(CO)₃, ³∑_g Fe(CO)₂, ³ ∑FeCO as well as positive ions ²A₁ Fe(CO)₅⁺, ⁴A₁ Fe(CO)₄⁺, ⁴A₁ Fe(CO)₃⁺,  ⁴∑_g Fe(CO)₂⁺ and ⁴ ∑ FeCO⁺. The structures and energies of the states have beendetermined and the calculated bond dissociation energies (BDEs) were compared with present experiments as well as with previous works.