  In chemistry, biology and materials science, the ability to access
interatomic interactions and their dynamical evolution has become possible with
the advent of femtosecond lasers. In particular, the observation of vibrational
wave packets via optical (UV-visible-IR) spectroscopies has been a major
achievement as it can track the motion of nuclei within the system. However,
optical spectroscopies only detect the effect of the interatomic vibrations on
the global electronic surfaces. New tuneable, pulsed and polarized sources of
short-wavelength radiation, such as X-Ray Free electron lasers, can overcome
this limitation, allowing for chemical and, of primary importance in
biochemistry, enantiomeric selectivity. This selectivity may be complemented by
taking into account the chemical shifts of atoms belonging to different
molecular moieties
