Rotational state selectivity in N 2 + X 2 Σ g + (&ngr; + = 0) by delayed pulsed field ionization spectroscopy via the a″ 1 Σ g + (&ngr;′ = 0) state

Author: Mackenzie S.R.   Merkt F.   Halse E.J.   Softley T.P.  

Publisher: Taylor & Francis Ltd

ISSN: 1362-3028

Source: Molecular Physics, Vol.86, Iss.5, 1995-12, pp. : 1283-1297

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Abstract

The pulsed field ionization (PFI) spectrum of nitrogen is recorded involving overall transitions from the neutral ground state, X 1 Σ g + (&ngr;″ = 0), to the lowest vibrational state of the ion, N 2 + X 2 Σ g + (&ngr; + = 0). In our apparatus, designed for the study of state selected ion-molecule reactions, it is demonstrated that clean populations of ions with rotational angular momentum quantum number N + = 0-6 can be produced by the PFI of high- n Rydberg states. These Rydberg states are populated here in a (2 + 1′) two-colour excitation scheme, resonant at the two-photon level with the a″ 1 Σ g + (&ngr;′ = 0) Rydberg state. More than 10 2 state selected ions are produced per laser pulse. Conclusive evidence is presented for rotational channel interactions being responsible for the enhanced relative intensities of the branches corresponding to transitions involving N + - J ′