  We present the intensive spectroscopic follow up of the type Ia supernova (SN
Ia) 2014J in the starburst galaxy M82. Twenty-seven optical spectra have been
acquired from January 22nd to September 1st 2014 with the Isaac Newton (INT)
and William Herschel (WHT) Telescopes. After correcting the observations for
the recession velocity of M82 and for Milky Way and host galaxy extinction, we
measured expansion velocities from spectral line blueshifts and
pseudo-equivalent width of the strongest features in the spectra, which gives
an idea on how elements are distributed within the ejecta. We position SN 2014J
in the Benetti (2005), Branch et al. (2006) and Wang et al. (2009) diagrams.
These diagrams are based on properties of the Si II features and provide
dynamical and chemical information about the SN ejecta. The nearby SN 2011fe,
which showed little evidence for reddening in its host galaxy, is shown as a
reference for comparisons. SN 2014J is a border-line object between the
Core-normal (CN) and Broad-line (BL) groups, which corresponds to an
intermediate position between Low Velocity Gradient (LVG) and High Velocity
Gradient (HVG) objects. SN 2014J follows the R(Si II)-\Delta m15 correlation,
which confirms its classification as a relatively normal SN Ia. Our description
of the SN Ia in terms of the evolution of the pseudo-equivalent width of
various ions as well as the position in the various diagrams put this specific
SN Ia into the overall sample of SN Ia.
