Decay rate measurement of the first vibrationally excited state of MgH$^+$ in a cryogenic Paul trap

TL;DR

This paper introduces a precise method to measure the decay rate of the first vibrationally excited state of MgH$^+$ ions in a cryogenic Paul trap, using laser excitation and resonance-enhanced dissociation.

Contribution

It presents a novel experimental technique for accurately determining vibrational decay rates of molecular ions in a cryogenic trap.

Findings

Decay rate measured with few percent accuracy

Method applicable to simple polar molecular ions

Enhanced understanding of molecular vibrational dynamics

Abstract

We present a method to measure the decay rate of the first excited vibrational state of simple polar molecular ions being part of a Coulomb crystal in a cryogenic linear Paul trap. Specifically, we have monitored the decay of the $|\nu$=$1,J$=$1 \rangle_X$ towards the $|\nu$=$0,J$=$0 \rangle_X$ level in MgH$^+$ by saturated laser excitation of the $|\nu$=$0,J$=$2 \rangle_X$-$|\nu$=$1,J$=$1 \rangle_X$ transition followed by state selective resonance enhanced two-photon dissociation out of the $|\nu$=$0,J$=$2 \rangle_X$ level. The technique enables the determination of decay rates, and thus absorption strengths, with an accuracy at the few percent level.