Fund Project:Project supported by the Scientific Research Program of the Higher Education Institution of Xinjiang, China (Grant Nos. XJEDU2016I051, XJEDU2017M042, XJEDU2018I020), the National Natural Science Foundation of China (Grant Nos. 11764041, 51462034), the Tianshan Youth Program of Xinjiang, China (Grant Nos. 2017Q033, 2017Q034), and the Natural Science Foundation of Xinjiang, China (Grant No. 2019D01A32).
Received Date:21 March 2019
Accepted Date:03 June 2019
Available Online:01 September 2019
Published Online:05 September 2019
Abstract:The dissociation dynamics of HD+ molecule in an intense field is investigated by using an accurate three-dimensional time-dependent wave packet approach. When the 790-nm laser pulse interacts with HD+ molecule, the lowest electronic 1sσ and 2pσ states are coupled. Due to the existence of the permanent electric dipole moment, the transitions in HD+ molecule involve the direct absorption of an odd and even number of photons, thereby opening different pathways for dissociation. The model of the photon-dressed states is presented to analyze the possible dissociation pathways of HD+ molecule. The laser-induced dissociation of HD+ molecule is mainly composed of the four pathways: the direct one-photon absorption, the net two-photon absorption, the direct two-photon absorption, and the direct two-photon absorption. To reveal the dissociation mechanism of HD+ molecule, the kinetic energy resolved spectra are calculated at the given laser intensities. It is found that the dissociation pathways are strongly dependent on laser intensity, especially for the net one-photon absorption dissociation and direct two-photon absorption dissociation. With further research, the dissociation pathways of HD+ are controlled by regulating the intensity of laser pulse. At a laser intensity of 4.0 × 1013 W/cm2, the kinetic energy resolved spectrum for the vibrational state ν = 3 includes the contributions from the net two-photon absorption dissociation and the direct two-photon absorption dissociation. For the vibrational state ν = 6, HD+ molecule is preferentially dissociated via the net one-photon absorption. However, the dissociation mechanism of HD+ molecule at the vibrational states ν = 3 and ν = 6 have significant changes as the laser intensity increases to 2.0 × 1014 W/cm2. For the vibrational state ν = 3, the branching ratio between the dissociation pathway of the net two-photon absorption and that of the direct two-photon absorption has a dramatic change with the increase of laser intensity. Compared with the kinetic energy resolved spectra at laser energy of 4.0 × 1013 W/cm2, the height of the dissociation peak from the net two-photon absorption decreases, and that of the direct two-photon absorption increases at laser intensity of 2.0 × 1014 W/cm2. For the vibrational state ν = 6, the dissociation process of the net one-photon absorption almost disappears at laser intensity of 2.0 × 1014 W/cm2, and it is replaced by the dissociation pathway of the direct two-photon absorption. Keywords:dissociation/ quantum control/ time-dependent wave packet method/ kinetic energy resolved spectra