A new source for vibrationally excited and rotationally cold metal-oxide molecules: spectroscopic characterization of the low-lying a3Π2 metastable excited state of the MgO molecule

Characterisation of the ground X+ 2ΠΩ and first excited A+ 2Σ+ electronic states of MgO+ by high-resolution photoelectron spectroscopy

“…In our R2PI spectrum, we also observed eight ( Ω ′ = 2)–( Ω ′′ = 2) transitions, in agreement with the earlier observation of multiple ( Ω ′ = 2)–( Ω ′′ = 2) transitions in the R2PI spectrum of MgO. 30 The analysis of the rotational structure of these eight bands using the PGOPHER® software 49 led to the results presented in Table 1 , where the term values T ′ of the upper states are given relative to the X 1 Σ + (0) ground state. The lower electronic state of all eight transitions can be unambiguously assigned to the a 3 Π 2 metastable state because the rotational-structure analysis resulted in values of (0.497(3) cm −1 ) and (0.493(3) cm −1 ), which agree within the experimental uncertainties with the rotational constants reported in ref.…”

“…In the first section of Table 1 , we report two transitions, the first of which has been reported by Bellert et al 30 and assigned by Maatouk et al 1 as the 3 3 Π 2 (0)–a 3 Π 2 (0) origin transition. In a later study, Bauschlicher and Schwenke 2 argued that the upper 3 Π 2 state actually is the fourth state of 3 Π 2 symmetry and should therefore be assigned as 4 3 Π 2 .…”

“…The lower electronic state of all eight transitions can be unambiguously assigned to the a 3 Π 2 metastable state because the rotational-structure analysis resulted in values of (0.497(3) cm −1 ) and (0.493(3) cm −1 ), which agree within the experimental uncertainties with the rotational constants reported in ref. 25 and 30 . Comparing the vibrational intervals observed in our spectrum with the fundamental interval of the a 3 Π 2 state reported by Bellert et al , 30 we could assign the lower levels of the observed bands to the first two vibrational levels ( v = 0, 1) of the a 3 Π 2 state.…”

“… 25 and 30 . Comparing the vibrational intervals observed in our spectrum with the fundamental interval of the a 3 Π 2 state reported by Bellert et al , 30 we could assign the lower levels of the observed bands to the first two vibrational levels ( v = 0, 1) of the a 3 Π 2 state. In the analysis of the rotational structure, we fixed the rotational constants to the values determined for these states by microwave spectroscopy.…”

“…Strong configurational mixing also affects the valence electronically excited states of MgO, 1,2,15,16,20,21 which have been studied experimentally by laser 18,22–24 and microwave 24,25 spectroscopy. Particularly noteworthy are the detailed investigations of the F 1 Π, E 1 Σ + and G 1 Π electronic states 26–29 and the 3 Π 2 states 30 at term values in the range of 36 000–40 000 cm −1 above the ground state. Breckenridge and coworkers have used these excited states to determine the adiabatic ionisation energy of MgO (64 578(7) cm −1 ) by resonance-enhanced two-photon ionisation (R2PI) spectroscopy.…”