Vibrational effects in the photo-ion yield spectrum of the SiH2+
molecular ion following 2p inner-shell excitation
Kennedy, Eugene T.ORCID: 0000-0002-0710-5281, Mosnier, Jean-PaulORCID: 0000-0002-9312-1754, van Kampen, Paul, Bizau, Jean-Marc, Cubaynes, Denis, Guilbaud, Ségolène, Carniato, Stéphane, Puglisi, AlessandraORCID: 0000-0002-8429-1639 and Sisourat, Nicolas
(2018)
Vibrational effects in the photo-ion yield spectrum of the SiH2+
molecular ion following 2p inner-shell excitation.
In: International Conference on Spectral Lines Shapes, 17-22 June 2018, Dublin, Ireland.
We report on complementary theoretical and laboratory investigations of the 2p ion
yield cross sections for the molecular-ion series SiHn
+
(n = 1, 2, 3), in the 95-108 eV photon
energy range, below the L-shell threshold. The experiments used an electron cyclotron
resonance (ECR) plasma molecular-ion source coupled with monochromatised synchrotron
radiation in a merged-beam configuration. The experimental spectra are compared with total
photoabsorption cross-sectional profiles calculated using an ab initio configuration interaction
method inclusive of spin-orbit coupling and the vibrational dynamics. The experimental results
show vibrationally resolved resonances for SiH2+ in the 98-102 eV range. The calculations
indicate twenty four core-excited states below the energy of 102 eV, of which only four
contribute significantly to the observed spectrum. These states correspond to the excitation of
an atomic-like 2p electron to the SiH2
+ (5a1) valence orbital.