Hyperfine interaction in molecular iodine between the 0+g, 1u and 0-u states correlating with the I(2P1/2) + I(2P1/2) dissociation limit

Abstract

The three-step three-color laser population of the I2(β1g, νβ, Jβ and D0+u, νD, JD) rovibronic states via those of the B0+u and 1u, 0+g(bb) states, correlating with the second and third dissociation limits of the valence states, has been used for the study of mechanisms of optical transitions involved in the population of the β1g, νβ, Jβ rovibronic states. It has been shown that the 1u(bb) ← B0+u transition is allowed due to hyperfine interactions of the 1u(bb), ν1u, J1u and 0+u(bb), ν0, J0 rovibronic states, though energy gaps between these pairs of the states are huge, greater than 0.7 cm−1. The ΔJ = ±2 lines observed in the β1g − 1u(bb) transition are also due to hyperfine interaction of the 1u(bb), ν1u, J1u and 0-u(bb), ν0, J0 rovibronic states. It has been also shown that the 1u(bb) ← B0+u transition cannot be attributed either to magnetic dipole or to electric quadrupole transitions. Contributions from the Stark effect in a strong laser field and from possible production of the I2(X)... I2(B) colliding pairs to mechanism of the 1u(bb) − B0+u transition are negligible.