The ultrafast photofragmentation pathway of N, N-dimethylisopropylamine

The spectroscopy, energy flow between excited states, and photochemical reaction dynamics of aliphatic amines illustrate the exquisitely complex interplay of competing phenomena on multiple time scales. This chapter investigates the femtosecond time-resolved dynamics of N, N-dimethylisopropylamine (DMIPA) using pump-probe mass spectrometry and photoelectron spectroscopy. The pathway of the fragmentation dynamics of DMIPA is determined via time-resolved mass and photoelectron spectroscopy. The dominant fragmentation mechanism is the cleavage of the α C-C bond. Upon excitation to 3. p, a rapid internal conversion to 3. s ensues, which deposits the energy needed for the fragmentation into vibrational degrees of freedom. At this energy, the bond cleavage does not, however, compete efficiently with the fluorescence decay, so that the bond does not break in the 3s state. The fragment ions are observed as a result of the bond cleavage of the molecular ions on their way to the mass spectrometer detector.