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Articles you may be interested inHigh resolution analysis of three bands of the electronic transition A2Σ+-X2Π of N2O+ radical: 100-000, 000-001, and 001-001The laser-induced fluorescence spectrum, Renner-Teller effect, and molecular quantum beats in the à 2 Π i -X̃ 2 Π i transition of the jet-cooled HCCSe free radical

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Accurate ab initio determination of the adiabatic potential energy function and the Born-Oppenheimer breakdown corrections for the electronic ground state of LiH isotopologues Threshold ion-pair production spectroscopy ͑TIPPS͒ has been applied to two isotopomers, HCl and DCl. From the high-resolution TIPP spectra the ion-pair thresholds of the two molecules have been precisely measured. Combined with the known ionization energy of H͑D͒ and the electron affinity of Cl, the difference between their bond dissociation energies is calculated, and therefore an experimental determination of the effect of Born-Oppenheimer breakdown on the dissociation limit of the ground state potential curve has been obtained. The difference in D e for the two isotopomers was found to be: D e (H-Cl)ϪD e (D-Cl)ϭ3.2Ϯ1.0 cm Ϫ1 . The bond energy for HCl was in agreement with our previous determination, D 0 (H-Cl)ϭ35748.2Ϯ0.8 cm Ϫ1 . These results are compared to a recent study of Born-Oppenheimer breakdown in HCl by Coxon and Hajigeorgiou, where high resolution spectroscopic data was used to fit Born-Oppenheimer breakdown correction terms for the intramolecular potential function. The present study also measured the high resolution spectra for photoion-pair production for HCl and DCl in the threshold region for ion-pair production ͑ϳ86 nm͒. Although there is qualitative agreement between the current results and previous experimental and theoretical work, there are some important differences. The possible mechanism for ion-pair formation in HCl and DCl is discussed in light of these high resolution results.

The A0 ϩ -X0 ϩ electronic transition of 172 Yb 32 S, 174 Yb 32 S, and 176 Yb 32 S has been rotationally analyzed for the first time. Doppler-limited laser excitation spectroscopy with selective detection of fluorescence was used to obtain spectra of the 0-0, 0-1, 1-1, 1-2, 2-2, and 2-3 bands with a measurement precision of approximately 0.003 cm Ϫ1 . The 2-2 and 2-3 bands were found to be perturbed by a level crossing that occurs in the A0 ϩ ϭ2 level. In total, over 1500 line positions have been measured, assigned, and employed in least-squares fits of molecular parameters. The principal deperturbed results for the X0 ϩ state, which arises primarily from the Yb 2ϩ (4 f 14 )S 2Ϫ electronic configuration, are R e ϭ2.3591(2) Å and e ( 174 YbS)ϭ366.714(2) cm Ϫ1 , and for the A0 ϩ state, R 0 ( 174 YbS)ϭ2.3905(2) Å.