## Abstract

The vibrational branching ratios (the ratios of the line strengths of Q branches) are measured for the first time in the v″ progressions of bands of the I^{1} Π_{g}
^{-}, v′, N → B^{1} Σ_{u}
^{+}, v″ transitions in the H_{2}, molecule for v′ = 0-3. v″ = 0-8, and N = 1-4. A significant discrepancy (reaching a factor of five) is found between the experimental data and the results of calculation in the Franck-Condon approximation. From a semiempirical analysis of our experimental data, the dependence of the dipole moment of the 3d^{1}Π_{g} → 2p^{1}Σ_{u}
^{+} electronic transition on the internuclear separation r is obtained. It is found that, for r = 1.5-3.0 au, a linear approximation of this dependence allows an adequate description of the whole set of the measured ratios of the transition probabilities. The r dependence of the dipole moment predicted by the semiempirical analysis is approximately twice as strong as that derived from the results of semiempirical calculations available in the literature. Relative values of the dependences of the (I^{1} Π_{g}
^{-}, J^{1} Δ_{u}
^{-} ). v′, N → B^{1} Σ_{u}
^{+}, v″ radiative transition probabilities on the vibrational quantum numbers v′ and v″ and the rotational quantum number N are obtained for v′ = 0-3. v″ = 0-9, and N = 1-6.

Original language | English |
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Pages (from-to) | 679-684 |

Number of pages | 6 |

Journal | Optics and Spectroscopy (English translation of Optika i Spektroskopiya) |

Volume | 83 |

Issue number | 5 |

State | Published - 1 Dec 1997 |

## Scopus subject areas

- Spectroscopy
- Atomic and Molecular Physics, and Optics