## Abstract

High n (=50-250) molecular Rydberg states are characterized by a high density (ρ ∝ n^{3}/2Ry) of electronic states and by unique intramolecular couplings (V) which involve long-range Rydberg electron-core multipole interactions. We explore spectroscopic and dynamic implications of the dipole coupling V = C_{D}(nn′)^{-3/2} of a doorway Rydberg state |n,l,N^{+},N〉 with a dense |{n′,l′,N^{+}-1,N〉} manifold (n′ > n) of bound Rydberg states, which are described by Hund coupling case (d). We establish the conditions for the realization of the statistical limit (Vρ ≫ 1 and γρ > 1) and of the sparse mixed level structure (Vρ ≫ 1 and γρ < 1) within the mixed electronic manifold (where γ = Γ_{0}/n^{3} are the nonradiative decay widths). The statistical limit for an electronic quasicontinuum is realized for the coupling strength domain 1.109Ry(B/Ry)^{3/8} < C_{D} < (Γ_{0}Ry/π)^{1/2}, establishing how the characteristics of the level structure and dynamics are determined by the rotational constant B, by the molecular dipole moment (C_{D} ∝ μ), by the decay width constant Γ_{0}, and by l (where C_{D} ∝ l^{-7}). The statistical limit within an electronic quasicontinuum is expected to be amenable for experimental observation in polar large molecules, while the np(N^{+}=0)-n′d(N^{+}=1) coupling in H_{2}O (Gilbert, R. D.; Child, M. S. Chem. Phys. Lett. 1991, 187, 153) corresponds to the sparse mixed level structure. Our analysis provides a generalization and unification of the theory of intramolecular coupling and dynamics for an electronic quasicontinuum.

Original language | English |
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Pages (from-to) | 11914-11919 |

Number of pages | 6 |

Journal | Journal of Physical Chemistry |

Volume | 100 |

Issue number | 29 |

DOIs | |

State | Published - 18 Jul 1996 |