The molecular structure of (Ref. 18).
The two orbitals included in the two-level model for the electronic structure of a molecule from which the x-ray absorption cross section is determined (Ref. 18). (a) The orbital; (b) the antibonding molecular orbital.
The time evolution of due to molecular rotation is shown for four temporal regimes of the laser pulse: (a) Impulsive alignment, ; (b) short-pulse intermediate regime (still almost impulsive), ; (c) long-pulse intermediate regime (quasiadiabatic), ; (d) adiabatic alignment, . Other computational parameters are and .
Influence of the temperature on the rotational dynamics of . The time evolution of is depicted for a linear rotor by the solid (black) curves for a range of temperatures given in blue. For comparison, we show results from a symmetric-rotor computation as dashed (green) curves. The Gaussian laser pulse with and is represented by the dash-dotted (red) curve.
Influence of the laser intensity on the maximally attainable alignment of . We show curves for the linear rotor as solid (black) lines and curves for the symmetric rotor as green (dashed) lines. The data are for various temperatures given by the numbers in blue. We use laser pulses with a FWHM duration of .
Study of the four regimes of the alignment of from Fig. 3 with a picosecond x-ray source . The dependence of [Eq. (7a)] on the time delay between laser and x-ray pulses is shown.
Impulsive alignment of studied by x-ray absorption. The setup is the one of the top panel in Figs. 3 and 6. The ratio [Eq. (7a)] is shown here. We use (top) and (bottom). Other computational parameters are and .
The relation of to the cross correlation ratios (dashed red), (solid black), and (dash-dot blue) [Eqs. (7a)–(7c)] for . The long dashed (green) vertical line indicates the value of a thermal ensemble. Other computational parameters are , , and .
Dependence of the x-ray absorption signal [Eq. (7a)] of on the rotational temperature of the molecules. The solid (black) curve is for and whereas the dashed (red) curve is for and . For both curves, the peak laser intensity is .
Exemplary one-dimensional control of x-ray absorption by laser-aligned molecules. In the upper panel, we show the induced molecular dynamics subject to the sequence of 50 laser pulses with intensity , which is shown in the lower panel. The individual pulses have a FWHM duration of and are spaced by 5.2 ps. The curves in the upper panel represent instantaneous ratios of cross sections: [Eq. (9b)] (dashed, red) and [Eq. (9c)] (solid, black). The rotational temperature is 1 K.
Dynamic average dipole polarizability and dynamic dipole polarizability anisotropy of a molecule in the field of a laser with photon energy determined with coupled-cluster linear-response methods for several basis sets (Ref. 7). Goebel and Hohm (Ref. 32) obtained the experimental values and
Thermally averaged rotational periods [Eq. (19)] for a number of rotational temperatures for the linear rotor model of . The periods were determined by using up to terms in the sum over in Eqs. (19) and (20).
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