title: Determination of the ground electronic state in transition metal halides: ZrF.
abstract: The spectroscopy of the ZrF radical, produced by a laser ablation-molecular beam experimental setup, has been investigated for the first time using a two-color two-photon (1 + 1') REMPI scheme and time-of-flight (TOF) mass spectrometry detection. The region of intense bands 400-470 nm has been studied, based upon the first spectroscopic observations of the isovalent ZrCl radical by Carroll and Daly. The overall spectrum observed is complex. However, simultaneous and individual ion detection of the five naturally occurring isotopologues of ZrF has provided a crucial means of identifying band origins and characterization via the isotopic shift, δ(iso), of the numerous vibronic transitions recorded. Hence, five (0-0) transitions, of which only two were free of overlap with other transitions, have been identified. The most intense (0-0) transition at 23113 cm(-1) presented an unambiguously characteristic RQP rotational structure. From rotational contour simulations of the observed spectra, the nature of the ground electronic state is found to be unambiguously of (2)Δ symmetry, leading to the assignment of this band as (0-0) (2)Δ ← X(2)Δ at 23113 cm(-1). A set of transitions (1-0) (2)Δ ← X(2)Δ at 22105 cm(-1) and (2-0) (2)Φ ← X(2)Δ at 22944 cm(-1) involving the X(2)Δ state has also been identified and analyzed. Furthermore, a second series of transitions with lesser intensity has also been related to the long-lived metastable (4)Σ(-) state: (3-0) (4)Π(-1/2) ← (4)Σ(-) at 21801 cm(-1), (2-0) (4)Π(-1/2) ← (4)Σ(-) at 21285 cm(-1) and (2-0) (4)Σ(-) ← (4)Σ(-) at 23568 cm(-1). These spectroscopic assignments are supported by MRCI ab initio calculations, performed using the MOLPRO quantum chemistry package, and show that the low-lying excited states of the ZrF radical are the (4)Σ(-) and (4)Φ states lying at 2383 and 4179 cm(-1) respectively above the ground X(2)Δ state. The difference in the nature of ground state and ordering of the first electronic states with TiF (X(4)Φ)(2-4) and ZrCl,(5) respectively, is examined in terms of the ligand field theory (LFT)(7) applied to diatomic molecules. These results give a precise description of the electronic structure of the low lying electronic states of the ZrF transition metal radical.
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (CNRS UMR 8214), Université Paris-Sud 11, Bâtiment 210, 91405 Orsay, France.
authors.forename: Satchin
authors.initials: S
authors.lastname: Soorkia
authors.forename: Niloufar
authors.initials: N
authors.lastname: Shafizadeh
authors.forename: Jacques
authors.initials: J
authors.lastname: Liévin
authors.forename: Marc-André
authors.initials: MA
authors.lastname: Gaveau
authors.forename: Christophe
authors.initials: C
authors.lastname: Pothier
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Mestdagh
authors.forename: Benoît
authors.initials: B
authors.lastname: Soep
authors.forename: Robert W
authors.initials: RW
authors.lastname: Field
mesh_terms: D002627:Chemistry, Physical; D004583:Electrons; D006219:Halogens / Q000737:chemistry*; D007834:Lasers; D008024:Ligands; D015394:Molecular Structure; D017785:Photons; D011789:Quantum Theory; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013816:Thermodynamics; D028561:Transition Elements / Q000737:chemistry*; D014732:Vibration
chemical_list: D006219:Halogens; D008024:Ligands; D028561:Transition Elements