Spectrum of AME-G353.05+16.90 in the ρ Ophiuchi molecular cloud after subtracting the best-fit free-free, CMB and thermal dust components. A theoretical spinning dust model consisting of two components is shown as the black solid line; the magenta dot-dashed line is for dense molecular gas and the green dotted line is for irradiated low density atomic gas (see Sect. 6). The 100/217 GHz data are contaminated by CO line emission and are not included in the fit.