Neutral photodissociation of superexcited states of molecular iodine

摘要

The formation of high-n Rydberg atoms from the neutral dissociation of superexcited states of I2 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 ~2SIGMA_8~+) converging on the I_2~+(B ~2SIGMA_8~+) 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(~3P_J)+I(~2P_(3/2)), where the I~*R(~3P_J) are Rydberg atoms converging on the I~+(~3P_J) states of the ion with J=2, 1, and 0. In the case of the I~*R(~3P2) fragments, the average Rydberg lifetime is observed to be 325±25 mu 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.