Isomeric Effects On Fragmentations Of Crotonaldehyde And Methacrolein In Low-energy Electron-molecule Collisions

Low kinetic energy (KE) electrons can induce various chemical events when allowed to interact with molecules of different sizes and complexities. We would report in this talk the fragmentation behavior of two isomeric molecules, crotonaldehyde (CA) and methacrolein (MA) upon impinging with low-energy electrons of kinetic energy in the range of 10-70 eV and the fragmentations have been probed by quadrupole mass spectrometry. At 10 eV, the mass spectra of both CA and MA show intense molecular ion peak at m/z 70, and also the peaks for H and CO loss channels at m/z 69 and m/z 42, respectively. A distinct peak for MA at m/z 41 (HCO loss) is observed at 10 eV whose intensity increases more rapidly than the case of CA. For MA, the CO loss channel is more preferred, while for CA it is the H loss channel. Electronic structure calculations reveal that these preferences are associated with relative energetic positions of the transition states, and the details will be presented in the talk