We study theoretically the photodissociation dynamics of the H_{2};{+} molecular ion exposed to a linearly polarized laser light. It is shown that it is possible to choose a laser wavelength and intensity so as to produce a coalescence of two photodissociation vibronic resonance states. At such a coalescence point, also called an exceptional point, the photodissociative resonance wave function is self-orthogonal. This unique phenomenon which is presented here for light induced molecular dynamics enables us to transfer completely the nondissociated molecules from one vibronic state to another by varying adiabatically the laser frequency and intensity along a closed contour which encircles the exceptional point.

New and existing spectroscopic data on N(2), obtained using a wide variety of experimental techniques, are interpreted using a coupled-channel Schrodinger-equation (CSE) model of the structure and predissociation dynamics for the interacting Rydberg and valence states of (3)Pi(u) symmetry. As a result, v>0 levels of the 3ppi(u)G(3) (3)Pi(u) Rydberg state are assigned correctly for the first time, leading to the identification of very strong perturbations in the G(3)-state vibrational structure. A four-channel CSE model, which includes the 3ssigma(g)F(3) (3)Pi(u) and 3ppi(u)G(3) (3)Pi(u) Rydberg states and the C(') (3)Pi(u) and C (3)Pi(u) valence states, indicates strong Rydberg-Rydberg coupling between the F(3) and G(3) states, strong Rydberg-valence coupling between the G(3) and C(') states, and weaker coupling between the F(3) and C(') states.