7 research outputs found
Multi-photon ionisation spectroscopy for rotational state preparation of N+2
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 N+2. 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
Rovibronic Spectroscopy of Sympathetically Cooled <sup>40</sup>CaH<sup>+</sup>
We measure the rovibronic
transitions <i>X</i> <sup>1</sup>Σ<sup>+</sup>, <i>v</i>″ = 0, <i>J</i>″ → <i>A</i> <sup>1</sup>Σ<sup>+</sup>, <i>v</i>′
= 0–3, <i>J</i>′
of CaH<sup>+</sup> and obtain rotational constants for the <i>A</i> <sup>1</sup>Σ<sup>+</sup> state. The spectrum is
obtained using two-photon photodissociation of CaH<sup>+</sup> cotrapped
with Doppler cooled Ca<sup>+</sup>. The excitation is driven by a
mode-locked, frequency-doubled Ti:Sapph laser, which is then pulse
shaped to narrow the spectral bandwidth. The measured values of the
rotational constants are in agreement with <i>ab initio</i> theory