| Autor: |
Wehrli, Dominik, Génévriez, Matthieu, Knecht, Stefan, Reiher, Markus, Merkt, Frédéric |
| Předmět: |
|
| Zdroj: |
Journal of Chemical Physics; 8/21/2020, Vol. 153 Issue 7, p074310-1-074310-17, 17p |
| Abstrakt: |
We report on the experimental observation of the B+2Σ+ state of MgAr+ located below the Mg+(3p²P3/2) + Ar(¹S0) dissociation asymptote. Using the technique of isolated-core multiphoton Rydberg-dissociation spectroscopy, we have recorded rotationally resolved spectra of the B+2Σ+(v′) ← X+ ²Σ+(v″ = 7) transitions, which extend from the vibrational ground state (v′ = 0) to the dissociation continuum above the Mg+(3p²P3/2) + Ar(¹S0) dissociation threshold. The analysis of the rotational structure reveals a transition from Hund’s angular-momentum-coupling case (b) at low v′ values to case (c) at high v′ values caused by the spin–orbit interaction. Measurements of the kinetic-energy release and the angular distribution of the Mg+ fragments detected in the experiments enabled the characterization of the dissociation mechanisms. The vibrational levels of the B+ state above v′ = 6 are subject to predissociation into the Mg+(3p²P1/2) + Ar(¹S0) continuum, and the fragment angular distributions exhibit anisotropy β parameters around 0.5, whereas direct dissociation into the continuum above the Mg+(3p²P3/2) + Ar(¹S0) asymptote is characterized by β parameters approaching 2. Molecular ions excited to the B+ state with v′ = 0–6 efficiently absorb a second photon to the repulsive part of the ²Σ+ state associated with the Mg+(3d ²D3/2,5/2) + Ar(¹S0) continua. The interpretation of the data is validated by the results of ab initio calculations of the low-lying electronic states of MgAr+, which provided initial evidence for the existence of bound vibrational levels of the B+ state and for the photodissociation mechanisms of its low vibrational levels. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
