Anti-alignment driven dynamics in the excited states of molecules under strong fields.

We develop two novel models of the H2+ molecule and its isotopes from which we assess quantum-mechanically and semi-classically whether the molecule anti-aligns with the field in the first excited electronic state. The results from both models allow us to predict anti-alignment dynamics even for the HD+ isotope, which possesses a permanent dipole moment. The molecule dissociates at angles perpendicular to the field polarization in both the excited and the ground electronic state, as the population is exchanged through a conical intersection. The quantum mechanical dispersion of the initial state is sufficient to cause full dissociation. We conclude that the stabilization of these molecules in the excited state through bond-hardening under a strong field is highly unlikely.

Self-modulation of nonlinear waves in a weakly magnetized relativistic electron-positron plasma with temperature.

We develop a nonlinear theory for self-modulation of a circularly polarized electromagnetic wave in a relativistic hot weakly magnetized electron-positron plasma. The case of parallel propagation along an ambient magnetic field is considered. A nonlinear Schrödinger equation is derived for the complex wave amplitude of a self-modulated wave packet. We show that the maximum growth rate of the modulational instability decreases as the temperature of the pair plasma increases. Depending on the initial conditions, the unstable wave envelope can evolve nonlinearly to either periodic wave trains or solitary waves. This theory has application to high-energy astrophysics and high-power laser physics.

Relativistic mass and charge of photons in thermal plasmas through electromagnetic field quantization.

An effective photon mass and equivalent photon charge are calculated for plasmas with finite temperature, by using a second covariant quantization of the electromagnetic field, which is based on a nonlinear magnetofluid unification field formalism. Relativistic effects are considered both in the fluid bulk motion and in the thermal motion. The effective relativistic photon mass is found for transverse and longitudinal photons, while the equivalent relativistic photon charge is obtained for purely transverse photons. Both quantum quantities are the relativistic generalization, at finite temperature, of previous results [Mendonça, et al., Phys. Rev. E 62, 2989 (2000)]. The dependence with temperature is studied in both cases.