High-resolution photoelectron spectroscopy of the ground and first excited electronic states of MgKr ⁺

High-Resolution Photoelectron Spectroscopy of the Ground and First Excited Electronic States of MgXe+

“…This is particularly the case for the transition to the v + = 0 level, which is much stronger in the experimental spectrum than in the calculated one. As in our analysis of the X + ← a photoionizing transition of MgAr + and MgKr + , we attribute this intensity anomaly to channel interactions, through which transitions to low vibrational levels of MgXe + with small Franck–Condon factors gain intensity by the coupling to Rydberg series converging to higher-lying vibrational levels of the ion. The photoionization spectrum supports this interpretation because a strong autoionization resonance is observed in Figure a at the position of the v + = 0 band of the PFI-ZEKE-PE spectrum.…”

“…The potential-energy function of the X + 2 Σ + state of MgXe + was determined from the vibrational structure of the PFI-ZEKE-PE spectrum in a least-squares fit. We calculated the vibrational term values by numerically solving the Schrödinger equation for the nuclear motion using a potential-energy function of the form V ( R ) = A .25em normale − 2 b ( R − R normale ) − C .25em normale − b ( R − R normale ) + u normalL normalR ( R ) following the same procedure as in our studies of MgAr + , , MgKr + , and MgNe + . The potential-energy function in eq comprises an attractive and a repulsive short-range interaction term and a long-range interaction term u LR ( R ).…”

“…The contours were modeled using standard expressions for a 2 Π – 2 Σ + transition, , assuming Hund’s case (b) for the X + state and Hund’s case (a) for the A + state. Initial values of the rotational constants were estimated by scaling the rotational constants of the A Ω + state of MgAr + and MgKr + and adjusted for each band to find the best agreement between the calculated and experimental contours. The overlap of the rotational structures of the different isotopomers made the fitting procedure challenging and resulted in large uncertainties for the rotational constants (the last column of Table ).…”

“…The experimental setup and procedure have been described in refs and with only minor adjustments made for the measurements reported in this study. A similar procedure was also used in studies of the electronic structure of other metal-containing molecular ions. − In summary, the experimental setup consists of a laser-ablation source of Mg in a pulsed supersonic expansion of a He/Xe gas mixture (10:1), generating a rotationally cold molecular beam containing MgXe in the a 3 Π 0 metastable state.…”

“…Here, we exploit the observation of the onset of the spin–orbit interaction-induced predissociation of the B + state of MgXe + to determine the position of the Mg + (3p) 2 P 1/2 + Xe 1 S 0 threshold, from which the other dissociation thresholds can be derived using thermochemical cycles. We used a similar strategy in our previous studies of MgAr + and MgKr + . The photoexcitation sequence is depicted in Figure .…”