Optimized right circularly polarized, ultrashort few-cycle laser pulse incident on the oriented BeO molecule and propagating along the molecular and space-fixed -axis during the revival of the field-free rotational wavepacket. Field-free orientation of the BeO molecule is induced by means of a picosecond laser pulse that is linearly polarized along the excitation field propagation direction axis (not shown). The parameters of the circularly polarized laser pulse are , (with a laser cycle of duration ), . The arrows indicate the sequence of few laser cycles as observed in the molecular frame when the pulse passes by.
Potential energy curves for the ground and lowest excited singlet states of the BeO molecule for bond lengths between and . The ionization potential of the ground state is marked. The arrow indicates the dipole-allowed electronic transition from the ground state into the excited or states (corresponding to excitation by means of a right or left circularly polarized ultrashort laser pulse, respectively), see also Fig. 1. The horizontal dashed line indicates the classically allowed vibrational range in the excited state between the classical turning points of and . The equilibrium bond length of the excited state is .
-component of the time-dependent electric field (panel a) and its intensity (panel b). The pulse parameters in Eq. (3) are , , , , , and . Panel c shows the thermally averaged time-dependent expectation value at . The orientation revivals (marked by vertical lines) are spaced by the rotational revival time of the electronic ground state . The orientation duration [taken to be the time at which ] is 0.34 ps.
Thermally averaged normalized angular distribution of the rotational wavepacket at times (bold curve) compared with the initial angular distribution (dashed curve).
- and -components of the time-dependent electric field and (panels a and b, respectively) and its intensity (panel c) for the optimized right circularly polarized ultrashort few-cycle laser pulse shown in Fig. 1. Panel d shows the corresponding population dynamics in the electronic , , and states at the equilibrium bond length of the BeO molecule.
Toroidal electronic current density [absolute values in atomic units and logarithmic scale ] (panel a) and induced magnetic field along the molecular axis (panel b, solid curve) for the state of the BeO molecule. The dotted curve compares the magnetic field with that computed for the state of the AlCl molecule (adapted from Ref. 19). The vertical lines indicate the positions of Be and O nuclei, and , respectively.
Electric ring current (panel a) and induced magnetic field at the O nucleus (panel b) vs the vibrational coordinate of the BeO molecule. The vertical lines indicate the various bond lengths , , and as shown in Fig. 2.
Quantum chemistry CASSCF/CASPT2 results for BeO at the equilibrium bond length .
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