Additionally, we show the signal of m/z = 16 (O or CH4) and m/z = 28 (CO), which we expect to occur as fragmentation products of CO2 . Direct identification of CH4 (CH4 + ) was not possible because of its overlap with the O + fragment signal, which appears with rather high intensity. For better comparison of the pulse shapes, we also present the pulses normalized to the maximum pulse height in Figure and. Changes in the individual pulse intensities during the initial and final five pulses as well as the resulting averaged intensities are illustrated in Figure in the Supporting Information, direct comparison between initial and final pulses is made in Figure .