Accurate Analytic Potential and Born鈥揙ppenheimer Breakdown Functions for MgH and MgD from a Direct-Potential-Fit Data Analysis

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• 作者：Robert D. E. Henderson ; Alireza Shayesteh ; Jason Tao ; Carl C. Haugen ; Peter F. Bernath ; Robert J. Le Roy
• 刊名：Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：December 19, 2013
• 年：2013
• 卷：117
• 期：50
• 页码：13373-13387
• 全文大小：754K
• 年卷期：v.117,no.50(December 19, 2013)
• ISSN：1520-5215

文摘

New high-resolution visible Fourier transform emission spectra of the A ²螤 鈫?X ²危⁺ and B鈥?²危⁺ 鈫?X ²危⁺ systems of ²⁴MgD and of the B鈥?²危⁺ 鈫?X ²危⁺ systems of ^25,26MgD and ^25,26MgH have been combined with earlier results for ²⁴MgH in a multi-isotopologue direct-potential-fit analysis to yield improved analytic potential energy and Born鈥揙ppenheimer breakdown functions for the ground X ²危⁺ state of MgH. Vibrational levels of the ground state of ²⁴MgD were observed up to v鈥?= 15, which is bound by only 30.6 卤 0.10 cm^鈥?. Including deuteride and minor magnesium isotopologue data allowed us also to determine the adiabatic Born鈥揙ppenheimer breakdown effects in this molecule. The fitting procedure used the recently developed Morse/Long-Range (MLR) potential energy function, whose asymptotic behavior incorporates the correct inverse-power form. A spin-splitting radial correction function to take account of the ²危 spin鈥搑otation interaction was also determined. Our refined value for the ground-state dissociation energy of the dominant isotopologue (²⁴MgH) is _e = 11鈥?04.25 卤 0.8 cm ^鈥?, in which the uncertainty also accounts for the model dependence of the fitted _e values for a range of physically acceptable fits. We were also able to determine the marked difference in the well depths of ²⁴MgH and ²⁴MgD (with the deuteride potential curve being 7.58 卤 0.30 cm^鈥? deeper than that of the hydride) as well as smaller well-depth differences for the minor ^25,26Mg isotopologues. This analytic potential function also predicts that the highest bound level of ²⁴MgD is v鈥?= 16 and that it is bound by only 2.73 卤 0.10 cm^鈥?.