Laser Intensity Dependence of Photoassociation in Ultracold Metastable Helium - Physics > Atomic PhysicsReport as inadecuate




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Abstract: Photoassociation of spin-polarized metastable helium to the three lowestrovibrational levels of the J=1, $0 u^+$ state asymptoting to 2$s{}^{3}$S$ {1}+2p {}^{3}$P$ {0}$ is studied using a second-order perturbativetreatment of the line shifts valid for low laser intensities, and two variantsof a non-perturbative close-coupled treatment, one based upon dressed states ofthe matter plus laser system, and the other on a modified radiative couplingwhich vanishes asymptotically, thus simulating experimental conditions. Thesenon-perturbative treatments are valid for arbitrary laser intensities and yieldthe complete photoassociation resonance profile. Both variants give nearlyidentical results for the line shifts and widths of the resonances and showthat their dependence upon laser intensity is very close to linear andquadratic respectively for the two lowest levels. The resonance profiles aresuperimposed upon a significant background loss, a feature for this metastablehelium system not present in studies of photoassociation in other systems,which is due to the very shallow nature of the excited state $0 u^+$ potential.The results for the line shifts from the close-coupled and perturbativecalculations agree very closely at low laser intensities.



Author: Daniel G Cocks, Ian B Whittingham

Source: https://arxiv.org/







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