  I Zw 1 is a well known narrow line quasar with very strong Fe II emission.
High S/N spectra obtained with the HST FOS show a remarkably rich emission line
spectrum. The C III$^* \lambda 1176$ line is clearly detected in emission for
the first time in AGNs. This line arises from radiative decay to the
$2s2p^3P^o_{0,1,2}$ metastable levels of C III. The observed flux is 50 larger
than expected from collisional excitation, or dielectronic recombination, in
photoionized gas. The most plausible mechanism for the large enhancement in the
C III^* \lambda 1176 flux is resonance scattering of continuum photons by C
III^* ions. This mechanism requires large velocity gradients 1000 km/s within
each emitting cloud in the BLR. Such large velocity gradients can be induced by
forces external to the gas in the BLR clouds, such as tidal disruption, or
radiation pressure.
