We present the spectra of 14 quasars with a wide coverage of rest wavelengths from 1000 to 7300 Å .
The redshift ranges from z = 0.061 to 0.555 and the luminosity from M _ { B } = - 22.69 to - 26.32 .
These spectra of high quality result from combining Hubble Space Telescope spectra with those taken from ground-based telescopes .
We describe the procedure of generating the template spectrum of Fe ii line emission from the spectrum of a narrow-line Seyfert 1 galaxy I Zw 1 that covers two wavelength regions of 2200 - 3500 Å and 4200 - 5600 Å .
Our template Fe ii spectrum is semi-empirical in the sense that the synthetic spectrum calculated with the CLOUDY photoionization code is used to separate the Fe ii emission from the Mg ii \lambda 2798 line .
The procedure of measuring the strengths of Fe ii emission lines is twofold ; ( 1 ) subtracting the continuum components by fitting models of the power-law and Balmer continua in the continuum windows which are relatively free from line emissions , and ( 2 ) fitting models of the Fe ii emission based on the Fe ii template to the continuum-subtracted spectra .
From 14 quasars including I Zw 1 , we obtained the Fe ii fluxes in five wavelength bands ( U 1 ( 2200 - 2660 Å ) , U 2 ( 2660 - 3000 Å ) , U 3 ( 3000 - 3500 Å ) , O 1 ( 4400 - 4700 Å ) , and O 2 ( 5100 - 5600 Å ) ) , the total flux of Balmer continuum , and the fluxes of Mg ii \lambda 2798 , H \alpha , and other emission lines , together with the full width at half maxima ( FWHMs ) of these lines .
Regression analysis was performed by assuming a linear relation between any two of these quantities .
Eight correlations were found with a confidence level higher than 99 % ; ( 1 ) larger Mg ii FWHM for larger H \alpha FWHM , ( 2 ) larger \Gamma for fainter M _ { B } , ( 3 ) smaller Mg ii FWHM for larger \Gamma , ( 4 ) larger Mg ii FWHM for smaller Fe ii ( O 1 ) /Mg ii , ( 5 ) larger M _ { BH } for smaller \Gamma , ( 6 ) larger M _ { BH } for smaller Fe ii ( O 1 ) /Mg ii , ( 7 ) larger [ O iii ] /H \beta for larger Mg ii FWHM , and ( 8 ) larger Fe ii ( O 1 ) /Mg ii for larger Fe ii ( O 1 ) /Fe ii ( U 1 ) .
The fact that six of these eight are related to FWHM or M _ { BH } ( \propto FWHM ^ { 2 } ) may imply that M _ { BH } is a fundamental quantity that controls \Gamma or the spectral energy distribution ( SED ) of the incident continuum , which in turn controls the Fe ii emission .
Furthermore , it is worthy of noting that Fe ii ( O 1 ) /Fe ii ( U 1 ) is found to tightly correlate with Fe ii ( O 1 ) /Mg ii , but not with Fe ii ( U 1 ) /Mg ii .