  The properties of the fluorescence Fe K-alpha emission lines of a sample of
38 quasars (QSOs) observed with XMM-Newton are studied. These objects are
included in the optically selected sample from the Palomar-Green (PG) Bright
Quasar Survey with an X-ray luminosity 1.3E43<L(2-10 keV)<5.1E45 ergs/s and
z<1.72. For each object in the sample, we investigated the presence of both
narrow and broad iron lines in detail. A total of 20 out of the 38 QSOs show
evidence of an Fe K-alpha emission line with a narrow profile. The majority of
the lines are consistent with an origin in low ionization material, which is
likely to be located in the outer parts of the accretion disk, the molecular
torus, and/or the Broad Line Region. The average properties of the narrow Fe
K-alpha emission line observed in the sample are similar to those of Seyfert
type galaxies as inferred from recent XMM-Newton and Chandra studies. A broad
line has been significantly detected in only three objects. Furthermore, we
studied the relationship between the equivalent width (EW) of the iron line and
the hard band X-ray luminosity for radio quiet quasars. The analysis indicates
that no clear correlation between the strength of the line and the hard X-ray
luminosity is present, and our results do not show compelling evidence for an
anticorrelation between these two quantities, i.e. the so-called X-ray Baldwin
effect.
