THE $(1s\sigma) (3p\sigma) B^{\prime}\Sigma^{+}_{u}\leftarrow (1s\sigma)^{2} X^{1}\Sigma^{+}_{g}$ SYSTEM OF THE HYDROGEN MOLECULE
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Date
1964
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Ohio State University
Abstract
The $B^{1}-X$ bands of the $H_{2}$ molecule have been studied in absorption with a 6.8 meter grazing incidence vacuum spectrograph. All the vibrational levels of the $B_{1}$ state have been observed up to its dissociation limit. Strong heterogenous perturbation between the $B^{1}$ and the $D^{1}\Pi_{u}^{+}$ states and relatively weak homogeneous perturbation between the B and the $B^{1}$ states have been noticed and their perturbation parameters have been determined. After deperturbation, an attempt has been made to obtain accurate rotational and vibrational constants for the $B^{1}$ state. Since both the $B^{1}_{v}$ and $\Delta G^{1}$ curves have very peculiar shapes, which might be due to a repulsion between the B and $B^{1}$ state at larger internuclear distances, it is difficult to represent the whole $B^{1}_{v}$ and $\Delta G^{1}$ curves by polynomial expansions. By examining the behavior of the least squares equations for the first four, five and six values of $B^{1}_{v}$ and $\Delta G^{1}$ in the region $v = 0$ to $v = -1/2$, the most likely equilibrium constants for the $B^{1}$ state are $\begin{array}{lrl}\omega_{e} = 2039.5 cm^{-1}, & \omega_{e}x_{e} = 83.41 cm^{-1}, & \omega_{e}y_{e} = 3.53 cm^{-1}\\ B_{e} = 26.349 cm^{-1}, & \alpha_{e} = 1.833 cm^{-1}, & \gamma_{e} = -0.0575 cm^{-1}\end{array}$ The present vibrational constants differ very much from those given by Monfils $(\omega_{e} = 2064.5 cm^{-1}, \omega_{e}x_{e} = 106.4 cm^{-1}, \omega_{e}y_{e} = 11.8 cm^{-1})$. This is because Monfils did not carefully examine the extrapolated portion of his equation for $\Delta G^{1}$ curve. In his case, as v tends to $-^{1}/_{2}$ the extrapolated portion of the curve bends upward very rapidly from the portion of the curve connecting the observed data points.
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Author Institution: Air Force Cambridge Research Laboratories, L. G. Hanscom Field