Energy Flow and Fragmentation Dynamics of N,N-Dimethylisopropylamine

Abstract

The energy flow and fragmentation dynamics of N,N-dimethylisopropylamine (DMIPA) upon excitation to the 3p Rydberg states has been investigated with use of time-resolved photoelectron and mass spectrometry. The 3p states are short-lived, with a lifetime of 701 +/- 45 fs. From the time dependence of the photoelectron spectra, we infer that the primary reaction channel leads to the 3s level, which itself decays to the ground state with a decay time of 87.9 +/- 10.2 ps. The mass spectrum reveals fragmentation with cleavage at the alpha C-C bond, indicating that the energy deposited in vibrations during the internal conversion from 3p to 3s exceeds the bond energy. A thorough examination of the binding energies and temporal dynamics of the Rydberg states, as well as a comparison to the related fragmentation of N,N-dimethyl-2-butanamine (DM2BA), suggests that the fragments are formed on the ion surfaces, i.e., after ionization and on a time scale much slower than the fluorescence decay from 3s to the ground state.

Atmospheric photochemical loss of H and H2from formaldehyde: the relevance of ultrafast processes

“…What is noteworthy about this observation is that Rydberg potential energy surfaces generally have the same shape along a given coordinate. 18,19 The reason for this is that the ionic core of the Rydberg-excited species determines the shape of the potential energy surface (the Rydberg electron is too far away from the nuclei to influence the energy). 19 In this case the Rydberg states are the exception to the rule, one possible explanation could be that the Rydberg orbitals pointing in the direction of the CQO group are significantly polarized.…”

Ultrafast Dynamics of 1,3-Cyclohexadiene in Highly Excited States

“…Rydberg fingerprint spectroscopy (RFS) takes advantage of the fact that the binding energies of electrons in Rydberg states are sensitive towards the arrangement of atoms in the ion core [15][16][17][18][19]. Because the structure in a Rydberg state most often closely resembles that of the ion state, the spectra of these states feature sharp peaks without vibrational broadening [20][21][22]. High time resolution of the method is obtained by using ultrafast, pulsed lasers in a pump-probe scheme [10,21].…”

“…Because the structure in a Rydberg state most often closely resembles that of the ion state, the spectra of these states feature sharp peaks without vibrational broadening [20][21][22]. High time resolution of the method is obtained by using ultrafast, pulsed lasers in a pump-probe scheme [10,21]. Importantly, the complexity of the Rydberg spectra does not scale with the size of the molecule.…”

Real-Time Probing of Structural Dynamics by Interaction between Chromophores

“…20 Because we often observe peaks from autoionizing superexcited states below 0.2 eV, all photoelectron spectra have been cut below this threshold.…”