  We present a computational study of the rotational molecular dynamics of
bromotrifluoromethane (CF3Br) molecules in gas phase. The rotation is
manipulated with an offresonant, 800nm laser. The molecules are treated as
rigid rotors. Frequently, we use a computationally efficient linear rotor model
for CF3Br which we compare with selected results for full symmetric-rotor
computations. The expectation value <cos^2 theta>(t) is discussed. Especially,
the transition from impulsive to adiabatic alignment, the temperature
dependence of the maximally achievable alignment and its intensity dependence
are investigated. In a next step, we examine resonant x-ray absorption as an
accurate tool to study laser manipulation of molecular rotation. Specifically,
we investigate the impact of the x-ray pulse duration on the signal
(particularly its temporal resolution), and study the temperature dependence of
the achievable absorption. Most importantly, we demonstrated that using
picosecond x-ray pulses, one can accurately measure the expectation value
<cos^2 theta>(t) for impulsively aligned CF3Br molecules. We point out that a
control of the rotational dynamics opens up a novel way to imprint shapes onto
long x-ray pulses on a picosecond time scale. For our computations, we
determine the dynamic polarizability tensor of CF3Br using ab initio molecular
linear-response theory in conjunction with wave function models of increasing
sophistication: coupled-cluster singles (CCS), second-order approximate
coupled-cluster singles and doubles (CC2), and coupled-cluster singles and
doubles (CCSD).
