(2+2)RESONANCE-ENHANCED MULTIPHOTON IONIZATION-FRAGMENTATION STUDY OF DIMETHYLAMINE

The multiphoton ionization spectra of dimethylamine are given in the 445-470 nm region. A time of flight mass spectrometer was used,and experiment was done under collision free condition. It is found that (2+2) resonance enhanced multiphoton ionization through (n_N,3s) Rydberg state produces parent ions which endure pseudo-$alpha$ and C—N bond cleavages. The former forms CH₃N⁺H=CH₂ ions,and the latter gives CH₂=N⁺H₂ ions .