Neutral dissociation of superexcited oxygen molecules in intense laser fields+

Di Song, Ali Azarm, Yousef Kamali, Kai Liu, Andong Xia, Yoshiaki Teranishi, Sheng Hsien Lin*, Fanao Kong, See Leang Chin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Superexcited states (SESs) of oxygen molecules and their neutral dissociation processes have been studied both experimentally and theoretically using intense femtosecond laser. We find that at the laser intensity of ∼2 × 1014 W/cm2, ultrashort laser pulse causes neutral dissociation of oxygen molecule by way of SESs. The dissociation products are the excited neutral oxygen atoms, which are observed through fluorescence spectroscopy. Laser power dependence of the fluorescence intensity shows that each molecule effectively absorbs an average of ten laser photons. The total energy absorbed is sufficient to stimulate the molecule to many of the SESs. The effect is equivalent to single photon excitation in the extreme-ultraviolet (XUV) region by synchrotron radiation (SR). Morse potential energy curves (PECs) are constructed for the SESs of O2 molecules. In light of the PECs, predissociation mechanism is proposed for the neutral dissociation. Quasiclassical trajectory (QCT) calculations show that the predissociation time is as short as 100 fs, which is consistent with our experimental measurement using ultrafast pump-probe technique.

Original languageEnglish
Pages (from-to)3087-3095
Number of pages9
JournalJournal of Physical Chemistry A
Volume114
Issue number9
DOIs
StatePublished - 11 Mar 2010

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