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Articles you may be interested inExperimental observation and analysis of the 3ν1(Σg) stretching vibrational state of acetylene using continuouswave infrared stimulated emission J. Chem. Phys. 139, 054201 (2013); 10.1063/1.4816524The rotational spectrum and dynamical structure of LiOH and LiOD: A combined laboratory and ab initio study A spectroscopic determination of the bond length of the LiOLi molecule: Strong ionic bonding Rotational coherence spectroscopy of para-cyclohexylaniline by stimulated Raman-induced fluorescence depletion and stimulated emission pumping Dispersed fluorescence ͑DF͒ and stimulated emission pumping ͑SEP͒ experiments have been carried out on the jet-cooled 7 Li 16 O 7 Li molecule. Rotationally resolved SEP bands to 2 l (lϭ0,2) vibrational angular momentum levels show that LiOLi is a linear molecule. The DF experiments have resulted in the measurement of 54 ( 1 , 2 l ,0) levels of the X 1 ⌺ g ϩ ground state, up to 6000 cm Ϫ1 . The energy levels determined experimentally are amazingly close to those calculated very recently for a high-level ab initio LiOLi(X 1 ⌺ g ϩ ) potential surface. The DF vibrational level energies are analyzed and discussed in terms of a global fit to an 11-term power series. From the SEP experiments, effective rotational constants B 1 , 2 l ,0 for several of these vibrational levels ͓including g ϩ (lϭ0) and␦ g (lϭ2) vibrational angular momentum states for ( 1 , 2 l у2(even), 3 ϭ0) levels͔ have also been determined. The bond distance R 0 is estimated to be 1.611Ϯ0.003 Å from an extrapolation of B 1 ,0,0 values. Finally, the unusual ''Li ϩ O Ϫ2 Li ϩ '' ionic bonding and the low 2 ϭ112 cm Ϫ1 bending frequency for LiOLi(X 1 ⌺ g ϩ ) are briefly discussed.

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Using laser induced fluorescence (LIF) and resonance enhanced two-photon ionization (R2PI) spectroscopy, several (ν1′,ν2′,ν3′) vibrational bands of the Ã 1B1(K′=1)←X̃ 1Σg+(0,0,0) perpendicular transition of the Li167O7Li molecule have been rotationally resolved and analyzed to yield effective A′,B′,C′ values. The estimated geometry of the Ã 1B1 state does not vary with ν1′ (symmetric stretch mode), but θ′ increases and R′ decreases slightly as ν2′ (bending mode) increases. Extrapolation leads to an estimate for the (0,0,0) state of θ0′=105±5°, R0′=1.86±0.04 Å, and for the potential minimum θe′=102±5°, Re′=1.87±0.04 Å. The strongly bent nature of the Ã 1B1 state is due to promotion of an O−2 p-electron (b1) from the strongly ionic, linear Li+O−2Li+ ground state to an a1 molecular orbital which has Li/Li bonding character. The Ã 1B1 state thus has an approximately Li+1/2O−1Li+1/2 charge distribution, so that the ionic bonding is less strong than in the linear ground state, where (from this study and an earlier stimulation-emission pumping study) R0″=1.611±0.003 Å. In fact, the Li–Li distance in the Ã 1B1 state, ∼3.0 Å, is quite similar to that of the Li2+1 ion, so the bonding may be described as that of Li2+1 bound ionically to the O−1 ion.