Extended Data Fig. 4: Comparison between the experimental IRMPD spectrum of m/z 130 produced in the reaction in the ion trap (grey) and the IRPD spectrum of m/z 130 formed inside the ion storage source (red).

To evaluate the B3LYP/N07D level of theory, the calculated anharmonic infrared spectra of quinolizinium+ (N-5) and H-quinoline+ (Ca-6) are plotted as orange and green sticks, respectively.