Neutral photodissociation of superexcited states of molecular iodine

The formation of high- n Rydberg atoms from the neutral dissociation of superexcited states of I 2 formed by resonant two-photon excitation of molecular iodine using an ArF laser has been investigated. The high- n Rydberg atoms I * are formed by predissociation of the optically excited molecular Rydberg states I 2 * [ R ( B Σ g + 2 ) ] converging on the I 2 + ( B Σ g + 2 ) state of the ion. Measurement of the kinetic energy release of the Rydberg I * fragments allowed the identification of the asymptotic channels as I * [ R ( P J 3 ) ] + I ( P 3 ∕ 2 2 ) , where the I * [ R ( P J 3 ) ] are Rydberg atoms converging on the I + ( P J 3 ) states of the ion with J = 2 , 1, and 0. In the case of the I * [ R ( P 2 3 ) ] fragments, the average Rydberg lifetime is observed to be 325 ± 25 μ s . Based on experiments on the variation of the Rydberg atom signal with the field ionizing strength, the distribution of Rydberg levels peaks at about 25 - 50 cm − 1 below the ionization limit.