Carbonyl sulphide under strong laser field: Time-dependent density functional theory

Abstract

To be published in The European Physical Journal D Abstract. The first 52 fs of a time evolution of the electron density in OCS after an interaction with an intense sub 10 fs laser pulse are studied using the time-dependent density functional theory. The nuclear motion in this linear trimer is simulated by the classical molecular dynamics method. Laser fields of intensity 10 13 W/cm 2 and 10 15 W/cm 2 are used. Details of the laser induced changes of the structure, as well as the ionization rate are sensitive to the applied field intensity and its polarization. It is found that under suitable conditions the OCS molecule bends soon after an interaction with a laser pulse. A deviation from the linear geometry of up to 23.6• and charged ions of up to +3 are observed. The time evolution of electric dipole moments and the time-dependent electron localization function (ELF) are also studied.

Atomic-resolution imaging of carbonyl sulfide by laser-induced electron diffraction

“…This suggests that in our experiment, with intensity ∼1 × 10 14 W/cm 2 and wavelength 2 µm, corresponding to a laser period of 6.6 fs, the molecular structure remains essentially unchanged during the time interval between ionization to recollision. In this context we note that recent ab-initio calculations 40 for laser pulses centered at 790 nm and an intensity of 1 × 10 15 W/cm 2 have shown that the atomic distances and bending angle ∠(O-C-S) are changing on a timescale longer than 10 fs, i. e., longer than the optical period in our experiment.…”

Molecular structure retrieval directly from laboratory-frame photoelectron spectra in laser-induced electron diffraction

“…Table 2 summarizes the potential energies and oscillator strengths for the first four excited electronic states of neutral OCS. Our results agree with previous ab initio calculations 40 . Moreover, in order to minimize the computational effort, simulations assume instantaneous delta pulse excitation to the excited state at the beginning of the simulation.…”

“…These authors assigned the recoil velocities from the (O 3+ , C 3+ , S 4+ ) channels to a bent structure (Φ OCS = 140°) just prior to Coulomb explosion. Recent ab initio calculations at 0.8 μm also revealed that structural deformation in OCS occurs on a timescale longer than 13 fs 40 , with wave packet simulations reporting that a linear-to-bent transition occurs on a 50-fs timescale, reaching an OCS bond angle of ~135° 37 .…”

Angle-Dependent Irradiation of C 4 in Femtosecond Laser Pulses

“…It is well known that the electron localization function (ELF) has become an important tool for a description of chemical bonds in molecules and solids. [26,27] Recently, Burnus et al [28] illustrated the usefulness of the time-dependent ELF in analyzing the creation and breaking of bonds. The two-dimensional representations of the ionic structure and the ELF contour plots for linear C 4 in the 𝑥𝑦 plane, the 𝑦𝑧 plane and the 𝑥𝑧 plane at 𝑡 = 0 fs and 𝑡 = 25 fs when the electron emission already reaches the saturation are presented in Fig.…”