Spectrum taken with the two central bolometers, SLWC3 (red) and SSWD4 (blue), from the center (blue pixel in Fig. 1) of the SPIRE FTS map of M 83. This spectrum has been corrected for the source-beam coupling effect with the method introduced in Wu et al. (2013). The source distribution is assumed to be a Gaussian profile with FWHM = 18′′, estimated from the overlap bandwidth of the two bolometers. The expected locations of the CO, [CI], and [NII] transitions listed in Table 1 are noted with the black dashed lines.