Figure 4

PIPICO map from dissociative ionization of CH₃OD. On the PIPICO map, the six vertical (dashed) lines represent the approximate center lines of the regions where H⁺, H₂ ⁺/D⁺, H₃ ⁺/HD⁺, H₂D⁺, CH₃ ⁺, and H₂O⁺ ions are recorded. The top horizontal (dashed) line indicates the COD⁺/H₂CO⁺ ion region and the bottom horizontal line indicates the COH⁺/HCO⁺ ion region. The contour region with an approximate slope of −1 at the intersection of the vertical H₂D⁺ line and the horizontal COH⁺/HCO⁺ line represents the coincidence channel of H₂D⁺  + HCO⁺ (red colored label) while the contour region at the intersection of the vertical H₃ ⁺/HD⁺ line and the horizontal COD⁺/H₂CO⁺ line represents the coincidence channel of H₃ ⁺  + COD⁺ (blue colored label). The coincidence channel of H₃ ⁺  + COH⁺/HCO⁺ due to CH₃OH contamination is visible as the contour region at the intersection of the vertical H₃ ⁺/HD⁺ line and the horizontal COH⁺/HCO⁺ line. A magnified view of these three channels is given in the inset. The logarithmic color scale depicts the event rate in units of events/shot.