Observation of the 4f\u21923d\u3c3 transition of the ArH molecule

The emission spectrum of ArH contains a band near 10 110 cm\u20131 that appears to be the analogue of the 3d \u2013 4p, v = 0 \u2013 0, band of ArD, observed and analysed near 10 230 cm\u20131. However, previous attempts to assign the rotational structure of this band of ArH were unsuccessful. Here we observe and analyse the 4f \u2013 3d band of ArH near 4400 cm\u20131, and are then able to calculate the rotational structure of the 3d \u2013 4p transition entirely from known data. The observed band is similar but not identical to the calculated band. We speculate that the observed spectrum is a v \u2013 v sequence band of 3d \u2013 4p, where the v 0 upper state is populated through some mechanism peculiar to this isotopomer.Le spectre d'\ue9mission de ArH contient une bande pr\ue8s de 10 110 cm\u20131 qui semble \ueatre l'analogue de la bande 3d \u2013 4p, v = 0 \u2013 0 de ArD observ\ue9e pr\ue8s de 10 230 cm\u20131. Les tentatives pr\ue9c\ue9dentes pour identifier la nature rotationnelle de cette bande ont \ue9chou\ue9. Ici, nous \ue9tudions la bande 4f \u2013 3d de ArH pr\ue8s de 4400 cm\u20131 et sommes alors capables de calculer la structure rotationnelle de la transition 3d \u2013 4p \ue0 partir de donn\ue9es connues. La bande observ\ue9e est similaire \ue0 celle calcul\ue9e, mais pas identique. Nous sp\ue9culons que le spectre observ\ue9 est une s\ue9quence v \u2013 v de 3d \u2013 4p o\uf9 l'\ue9tat sup\ue9rieur v 0 est peupl\ue9 via un m\ue9canisme particulier \ue0 cet isotopom\ue8re.NRC publication: Ye