Rotationally resolved photodissociation spectroscopy of Mg+–Ar

The metal ion-complex 24Mg+–Ar has been prepared in a pulsed nozzle/laser vaporization source, mass selected with a reflection time-of-flight mass spectrometer and studied with photodissociation spectroscopy at high resolution. The (5,0) band of the A 2Πr←X 2Σ+ transition has been rotationally analyzed and the rotational constants, B″=0.1409(7) cm−1 and B′=0.1836(8) cm−1, and spin–orbit constant, A′=73.94(2) cm−1, have been determined. The bond distances in the ground and excited states of the complex (r0″=2.88 Å, r5′=2.52 Å) compare well with the values predicted by theory, and they confirm the suspected nature of the electrostatic bonding in this system.