IRPD spectrum of Ne-tagged dications naph²⁺, phen²⁺, and anth²⁺ compared to calculated anharmonic (B3LYP/6-311+G(d,p)) spectra, respectively. The calculated spectrum was convoluted with a Gaussian lineshape function, where the width is givenby the FEL bandwidth, and the area corresponds to the calculated intensity in km mol⁻¹. The spectrum in the bottom panel is the anth²⁺-Ne spectrum subtracted by 30% of the weight of the relative intensity of the phen²⁺ -Ne spectrum to account for the contaminated bands.