Multi-photon ionisation spectroscopy for rotational state preparation of N2+

Amy Gardner, Timothy Softley, Matthias Keller*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


In this paper we investigate the 2 + 1′ resonance enhanced multi-photon ionisation (REMPI) of molecular nitrogen via the a1Πg(v = 6) intermediate state and analyse its feasibility to generate molecular nitrogen ions in a well defined ro-vibrational state. This is an important tool for high precision experiments based on trapped molecular ions, and is crucial for studying the time variation of the fundamental constant mp/me using N2+. The transition is not reported in the literature and detailed spectral analysis has been conducted to extract the molecular constants of the intermediate state. By carefully choosing the intermediate ro-vibrational state, the ionisation laser wavelength and controlling the excitation laser pulse energy, unwanted formation of rotationally excited molecular ions can be suppressed and ro-vibrational ground state ions can be generated with high purity.

Original languageEnglish
Article number506
JournalScientific Reports
Issue number1
Publication statusPublished - 1 Dec 2019

Bibliographical note

Funding Information:
We gratefully acknowledge support from the Engineering and Physical Sciences Research Council of the UK (EPSRC) (EP/N004930/1).

Publisher Copyright:
© 2019, The Author(s).

ASJC Scopus subject areas

  • General


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