Left panel: Continuum image at 232 GHz (1.290 mm). The colour scale ranges from 0.001 to 0.2 Jy beam⁻¹. The contour levels are indicated on the colour bar. The ALMA beam is plotted on the lower left corner. Right panel: Observed spectra between 215 810 and 215 870 MHz, towards B1b-N (top panel) and B1b-S (bottom panel). Brightness temperaturescale, in K, is given on the left. Line features with no labels are unidentified lines. The LTE simulations are over-plotted in red for B1b-S.