Abstract:

Multiphoton ionization-dissociation process of Methylamine Molecules is studied using Time-Of-Flight mass spectrometer with a pulsed dye laser. Four ion peaks observed under different laser wavelength and laser power are assigned to CH3NH2+、CH2NH2+、 CHNH2+ (CH2NH+) and CHNH+. Based on the experimental results, the Multiphoton lonization and Dissociation(MPID) mechanism of CH3NH2 are discribed:CH3NH2 molecule is ionized to generate CH3NH2+ via 2+2 photon(two photon resonant excitation and two photon ionization)process. CH3NH2+ dissociate to produce CH2NH2+. CHNH2+(CH2NH+) and CHNH+ are generated by the consequent dissociation of CH2NH2+. The experimental results indicate that the dissociation rate constant of CH3NH2+ decreases as laser wavelength increases.

Key words: Methylamine, Multiphoton ionization and dissociation(MPID), Time-of-flight mass spectrometer(TOF-MS)