Experimental Investigation on Resonance-Enhanced Multiphoton Ionization of Methylamine

摘要

By means of time of flight (TOF) mass spectrometry, multi-photon ionization dissociation kinetics is employed in the paper to study methylamine molecules within the wavelength of 280-287.5nm under supersonic jet condition. The analysis of result achieved in TOF mass spectrometry and sub-excitation spectrum shows that the primary process of multi-photon dissociation and ionization of methylamine molecules within the wavelength of 280-287.5nm is that through a electron repulsion state one photon absorbed by parent molecule resonance is dissociated into neutral CH2NH2 fragments. Then the neutral CH2NH2 dissociation fragments absorb photon, causing (1+1) resonant multi-photon ionization to generate excited states of CH2NH2+ fragments. CH2NH2+ under the pre-dissociation electronic excited state is dissociated further into ion fragments like CH2CH+,CHNH+,CNH+(CHN+), while the feeble parent ion signal is formed through absorbing two photon ionization after the parent molecule absorbed a photon to reach an electronic repulsion state.