  Domain structure of paracetamol -- popular antipyretic analgesic -- was
investigated by infrared (IR) spectroscopy using synchrotron radiation.
Absorbance and retardance maps reveal molecular orientation inside the
micro-domains of the paracetamol form II which has a better water solubility
and compressibility compared to the commercially used forms I. The developed
method of analysis representing orientation of optical slow(fast)-axis is
compared with azimuthal orientation of the absorbance at several specific IR
bands using vector maps. High brightness of synchrotron radiation and
hyper-spectral mapping of structural domains in paracetamol clearly reveals the
domain boundaries and can potentially be used to observe \emph{in situ}
intra-phase transformations of paracetamol forms-I, II, III and melting, which
are important for making medical tablets and powders by an industrial process.
