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We investigate the strength of ultraviolet Fe II emission in fainter quasarscompared with brighter quasars for 1.0 <= z <= 1.8, using the SDSS (SloanDigital Sky Survey) DR7QSO catalogue and spectra of Schneider et al., and theSFQS (SDSS Faint Quasar Survey) catalogue and spectra of Jiang et al. Wequantify the strength of the UV Fe II emission using the W2400 equivalent widthof Weymann et al., which is defined between two rest-frame continuum windows at2240-2255 and 2665-2695 Ang. The main results are the following. (1) We findthat for W2400 >~ 25 Ang. there is a universal (i.e. for quasars in general)strengthening of W2400 with decreasing intrinsic luminosity, L3000. (2) Inconjunction with previous work by Clowes et al., we find that there is afurther, differential, strengthening of W2400 with decreasing L3000 for thosequasars that are members of Large Quasar Groups (LQGs). (3) We find thatincreasingly strong W2400 tends to be associated with decreasing FWHM of theneighbouring Mg II {\lambda}2798 broad emission line. (4) We suggest that thedependence of W2400 on L3000 arises from Ly{\alpha} fluorescence. (5) We findthat stronger W2400 tends to be associated with smaller virial estimates fromShen et al. of the mass of the central black hole, by a factor ~ 2 between theultrastrong emitters and the weak. Stronger W2400 emission would correspond tosmaller black holes that are still growing. The differential effect for LQGmembers might then arise from preferentially younger quasars in the LQGenvironments.

Ultraviolet Fe II Emission in Fainter Quasars: Luminosity Dependences, and the Influence of Environments