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arXiv · 1207.4740

Ultrafast dynamics of neutral superexcited Oxygen: A direct measurement of the competition between autoionization and predissociation

Henry Timmers·Niranjan Shivaram·Arvinder Sandhu
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Abstract

Using ultrafast extreme ultraviolet pulses, we performed a direct measurement of the relaxation dynamics of neutral superexcited states corresponding to the nlσ_g(c^4Σ_u^-) Rydberg series of O_2. An XUV attosecond pulse train was used to create a temporally localized Rydberg wavepacket and the ensuing electronic and nuclear dynamics were probed using a time-delayed femtosecond near-infrared pulse. We investigated the competing predissociation and autoionization mechanisms for superexcited molecules and found that autoionization is dominant for the low n Rydberg states. We measured an autoionization lifetime of 92+/-6 fs and 180+/-10 fs for (5s,4d)σ_g and (6s,5d)σ_g Rydberg state groups respectively. We determine that the disputed neutral dissociation lifetime for the ν=0 vibrational level of the Rydberg series is 1100+/-100fs.

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Henry Timmers, Niranjan Shivaram, Arvinder Sandhu. 2012-10-15. Ultrafast dynamics of neutral superexcited Oxygen: A direct measurement of the competition between autoionization and predissociation. https://doi.org/10.1103/physrevlett.109.173001

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