- Rotational population distribution of KH (v=0, 1, 2, and 3) in the reaction of K(52PJ, 6 2PJ, and 72PJ) with H2: Reaction mechanism and product energy disposal
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Using a pump-probe method, we have systematically studied the rotational distribution of KH (v=0-3) produced in the reaction of K (5P, 6P, and 7P) with H2. The resulting rotational states fit roughly a statistical distribution at the system temperature, while the vibrational populations are characterized by a Boltzmann vibrational temperature of 1800, 3000, and 3100 K for the 5p, 6P, and 7P states, respectively. These results provide evidence that the reaction follows a collinear collisional geometry. This work has successfully probed KH from the K(5P) reaction, and confirms that a nonadiabatical transition via formation of an ion-pair K+H2- intermediate should account for the reaction pathway. The available energy dissipation was measured to be (68±4)%, (26±2)%, and (6±3)% into the translation, vibration, and rotation of the KH product, respectively. The energy conversion into vibrational degree of freedom generally increases with the principal quantum number, indicating that the electron-jump distance elongates along the order of 5P2 case, in which the electron-jump distances were considered roughly the same. Furthermore, a relatively large distance is expected to account for highly vibrational excitation found in the KH product. According to the classical trajectory computation reported by Polanyi and co-workers, the strong instability of the H2- bond, inducing a large repulsion energy, appears to favor energy partitioning into the translation.
- Liu, Dean-Kuo,Lin, King-Chuen
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- Chemical dynamics of the reaction K*(5p2P) + H2→KH(v=0; J)+H: Electronic orbital alignment effects
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We report results from scattering state spectroscopic studies of the excited state reaction K*(5p 2P) + H2→KH(ν″,J″)+H. The final state resolved action spectra allow a direct measurement of essential features of the excited state potential surfaces, including regions of local maxima and minima. We observe a pronounced blue-wing-red-wing asymmetry in the reactive to nonreactive branching ratio, peaking in the neighborhood of a strong blue wing satellite. These results show that the dominant reaction pathway passes over a small activation barrier (350 ± 100 cm-1) in Σ+-like orbital alignment. This result is consistent with an electron jump mechanism through a K+H-H ion-pair intermediate. In contrast, approach in Π-like alignment leads predominantly to nonreactive scattering. Our results suggest that a combination of steric and energetic effects determine the major quenching pathways for alkali metal atom-H2 systems.
- Wong,Kleiber,Yang
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- The intensity behaviour of the laser-induced fluorescence spectrum in the KH molecule
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Collosional processes involving changes in rotational and vibrational quantum numbers are detected in laser induced fluorescence spectrum of KH molecule.The knowledge of the Franck-Condon factors in the involved transitions allows us to evaluate a relative variation of R2e versus the ν'' vibrational quantum number.In the same context a population analysis was made for the ν'=7 vibrational level.
- Pardo, A.,Poyato, J. M. L.,Camacho, J. J.
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- Spectroscopy of the NaH, NaD, KH, and KD X 1Σ+ ground state by laser excited fluorescence in a high frequency discharge
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By laser excited fluorescence of the hydrides obtained in a discharge, the ground state vibrational levels of NaH, NaD, KH, and KD, have been observed up to v = 15, 20, 14, and 16, respectively , instead of v = 8,2 , 4, and 4 by conventional spectroskopy.Experimental values of Gv , Bv , and Dv are obtained.Spectroscopic parameters and RKR potential curves are calculated.In NaH and NaD, a comparison can be made with ab initio calculations.
- Giroud, Marc,Nedelec, O.
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p. 4151 - 4155
(2007/10/02)
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