The isotopic dependence of Born-Oppenheimer breakdown effects: Application of a Hamiltonian correction approach to the representation of spectroscopic line positions of hydrogen fluoride/deuterium fluoride and hydrogen chloride/deuterium chloride.
Date
1990
Authors
Hajigeorgiou, Photos George.
Journal Title
Journal ISSN
Volume Title
Publisher
Dalhousie University
Abstract
Description
Pure rotational transitions of DF$(X\sp1\Sigma\sp+)$ with 1 $\leq J\sp{\prime\prime}\leq$ 8 in $\upsilon\sp{\prime\prime}$ = 0 were obtained precisely with a state-of-the-art Fourier transform spectrometer. These data were combined with selected spectroscopic data for DF$(\upsilon\sp{\prime\prime}$ = 0-4) in a least-squares determination of Dunham coefficients.
The $B\sp1\Sigma\sp+ - X\sp1\Sigma\sp+$ ultraviolet emission band system of DF was recorded spectrographically in the region 205-275 nm. Computer assisted rotational analyses of 41 bands with 0 $\leq\upsilon\sp\prime\leq$ 5 and 16 $\leq\upsilon\sp{\prime\prime}\leq$ 26 resulted in band origins and rotational parameters for both electronic states.
The $B\sp1\Sigma\sp+ - X\sp1\Sigma\sp+$ emission bands of DCl in the region 166-240 nm were photographed in higher orders of a 10.7-m concave grating vacuum spectrograph. Rotational analyses of 56 bands of D$\sp{35}$Cl with $\upsilon\sp\prime$ = 0-7 and $\upsilon\sp{\prime\prime}$ = 11-23 furnished molecular parameters for both states.
All reliable literature data for the $X\sp1\Sigma\sp+(\upsilon\sp{\prime\prime}$ = 0-19) and $B\sp1\Sigma\sp+(\upsilon\sp\prime$ = 0-10) states of HF and the $X\sp1\Sigma\sp+(\upsilon\sp{\prime\prime}$ = 0-26) and $B\sp1\Sigma\sp+(\upsilon\sp\prime$ = 0-7) states of DF were employed to determine isotopically self-consistent radial operators which take full account of Born-Oppenheimer breakdown. The dissociation energy of DF($X\sp1\Sigma\sp+$) was estimated as ${\cal D}\sb{e}$ = 49338(45) cm$\sp{-1}$ and the vibrational index at dissociation as $\upsilon\sb{\rm D}$ = 29.2(5). The electronic isotope shift of $B\sp1\Sigma\sp+$ was estimated as $\Delta T\sb{e}$ = $-$2.48(7) cm$\sp{-1}$. Rotationally dependent Franck-Condon factors for the $B\to X$ transition and Einstein coefficients for spontaneous emission in $X\sp1\Sigma\sp+$ were calculated. Rotational assignments for the $B\sp1\Sigma\sp+ - X\sp1\Sigma\sp+$ emission band system of DF were extended significantly.
A similar analysis of data for H$\sp{35}$Cl, H$\sp{37}$Cl, D$\sp{35}$Cl, and D$\sp{37}$Cl was performed. A simultaneous four-isotopomer least-squares fit of 8497 line positions resulted in Born-Oppenheimer potentials for the $B\sp1\Sigma\sp+$ and $X\sp1\Sigma\sp+$ states and radial functions which describe adiabatic and nonadiabatic effects. The electronic isotope shift of $B\sp1\Sigma\sp+$ was obtained as $\Delta T\sb{e}$ = $-$11.11(3) cm$\sp{-1}$. Rotational assignments for the $B\sp1\Sigma\sp+ - X\sp1\Sigma\sp+$ emission band system of D$\sp{35}$Cl were extended and the first set of assignments for the $B\to X$ system of D$\sp{37}$Cl was obtained. Quantum mechanical rotational and centrifugal distortion constants were calculated for TCl. As was the case for HF/DF, the repulsive $A\sp1\Pi$ state of HCl/DCl was found to perturb significantly the energy level manifold of $X\sp1\Sigma\sp+$ in a heterogeneous fashion.
Thesis (Ph.D.)--Dalhousie University (Canada), 1990.
The $B\sp1\Sigma\sp+ - X\sp1\Sigma\sp+$ ultraviolet emission band system of DF was recorded spectrographically in the region 205-275 nm. Computer assisted rotational analyses of 41 bands with 0 $\leq\upsilon\sp\prime\leq$ 5 and 16 $\leq\upsilon\sp{\prime\prime}\leq$ 26 resulted in band origins and rotational parameters for both electronic states.
The $B\sp1\Sigma\sp+ - X\sp1\Sigma\sp+$ emission bands of DCl in the region 166-240 nm were photographed in higher orders of a 10.7-m concave grating vacuum spectrograph. Rotational analyses of 56 bands of D$\sp{35}$Cl with $\upsilon\sp\prime$ = 0-7 and $\upsilon\sp{\prime\prime}$ = 11-23 furnished molecular parameters for both states.
All reliable literature data for the $X\sp1\Sigma\sp+(\upsilon\sp{\prime\prime}$ = 0-19) and $B\sp1\Sigma\sp+(\upsilon\sp\prime$ = 0-10) states of HF and the $X\sp1\Sigma\sp+(\upsilon\sp{\prime\prime}$ = 0-26) and $B\sp1\Sigma\sp+(\upsilon\sp\prime$ = 0-7) states of DF were employed to determine isotopically self-consistent radial operators which take full account of Born-Oppenheimer breakdown. The dissociation energy of DF($X\sp1\Sigma\sp+$) was estimated as ${\cal D}\sb{e}$ = 49338(45) cm$\sp{-1}$ and the vibrational index at dissociation as $\upsilon\sb{\rm D}$ = 29.2(5). The electronic isotope shift of $B\sp1\Sigma\sp+$ was estimated as $\Delta T\sb{e}$ = $-$2.48(7) cm$\sp{-1}$. Rotationally dependent Franck-Condon factors for the $B\to X$ transition and Einstein coefficients for spontaneous emission in $X\sp1\Sigma\sp+$ were calculated. Rotational assignments for the $B\sp1\Sigma\sp+ - X\sp1\Sigma\sp+$ emission band system of DF were extended significantly.
A similar analysis of data for H$\sp{35}$Cl, H$\sp{37}$Cl, D$\sp{35}$Cl, and D$\sp{37}$Cl was performed. A simultaneous four-isotopomer least-squares fit of 8497 line positions resulted in Born-Oppenheimer potentials for the $B\sp1\Sigma\sp+$ and $X\sp1\Sigma\sp+$ states and radial functions which describe adiabatic and nonadiabatic effects. The electronic isotope shift of $B\sp1\Sigma\sp+$ was obtained as $\Delta T\sb{e}$ = $-$11.11(3) cm$\sp{-1}$. Rotational assignments for the $B\sp1\Sigma\sp+ - X\sp1\Sigma\sp+$ emission band system of D$\sp{35}$Cl were extended and the first set of assignments for the $B\to X$ system of D$\sp{37}$Cl was obtained. Quantum mechanical rotational and centrifugal distortion constants were calculated for TCl. As was the case for HF/DF, the repulsive $A\sp1\Pi$ state of HCl/DCl was found to perturb significantly the energy level manifold of $X\sp1\Sigma\sp+$ in a heterogeneous fashion.
Thesis (Ph.D.)--Dalhousie University (Canada), 1990.
Keywords
Physics, Molecular.