Constantin Mainos

Multiphoton rotational line strength in diatomic molecules between two Hund's case (a) states

The n-photon rotational line strength (RLS) in diatomic molecules is studied for transitions between two states which both belong to Hunds case (a). The expression of the n-photon RLS is given for n identical photons linearly polarized and n identical photons circularly polarized, in the Born-Oppenheimer approximation and neglecting rotational contributions to the energies of the intermediate states. The selection rules are also given.

Multiphoton rotational line strengths in diatomic molecules for intermediate Hund's (a-b) coupling case

Rotational line strength expressions are derived for n-photon transitions between two multiplet states of diatomic molecules which both belong to coupling cases that are intermediate between Hunds case (a) and case (b). Rotational selection rules for n-photon transitions are given. For doublet states, rotational line strengths are given in terms of coupling parameters, states with any multiplicity may be treated in the same way. Different kinds of transitions are discussed.

The single path rotational structure of n-photon transitions in diatomic molecules

The present work considers the n-photon rovibronic transitions in the case where some predominant molecular path is present. Each molecular path produces a distinct rotational structure. The intensity of any rotational line as well the polarization intensity ratio are derived. A single path, relative weighting tensor is introduced which describes the influence of the molecular transitional path on the rotational structure.

Molecular orientation effects in coherent anti-Stokes Raman scattering

The dependence of CARS susceptibilities on molecular orientation is considered for a diatomic or symmetric-top molecule. The angular distribution of the internuclear axis during an excitation time interval that is short compared with a simple molecular rotation was investigated. The part of the molecules involved in the excited channels of the two-photon resonance and their angular distribution were deduced.

Pressure effects in multiple resonant multiphoton transitions

Abstract Although the rotational structure of a multiphoton process generally remains unaltered over a large range of gas pressure, this is not the case when multiple resonances are present. The rotational structure observed through intermediate rotational levels in a multiphoton process depends strongly on the resonance conditions. We show, for the NO molecule, that this structure changes drastically when the resonance conditions are modified by intermolecular collisions.

Internuclear-axis angular distribution in multiphoton excitation

The internuclear-axis angular distribution is investigated in a nonresonant multiphoton process. This is done for diatomic or symmetric-top molecules and for singlet molecular states or any state which is well described by Hunds case (a) electronic coupling. The electric dipole approach is used for the description of the interaction of the electromagnetic radiation with the molecule and explicit expressions, either for resolved or unresolved magnetic levels, are derived. The obtained simulated results are compared with excitation spectra available in the literature

Molecular axis orientation and transitional path effects in the rotational structure of multiphoton transitions

The intensity distribution among the rotational branches in a multiphoton process is considered. It is shown that the excitation probability of a rotational line depends drastically on the transitional path involved as well as on the molecular axis orientation. Each transitional path derives a distinct rotational structure and the intensity distribution of the rotational branches in the excitation spectra reveals the dominant transitional path.