Understanding of structural, reaction and charge transfer dynamics of any molecular system has been a challenge for both modern spectroscopists and theorists. The structural changes after an excitation can be very fast, playing out on time frames of femtoseconds. Structural changes in large molecules such as proteins or enzymes are induced by seemingly small triggers, for example a simple carbon – carbon bond rotation, charge transfer, a hydrogen bond formation or a simple bond dissociation. Our studies of model systems in molecular beams help us to understand these structural changes without any interference from other effects. In our approach we use time resolved photoelectron spectroscopy coupled with mass spectrometry to explore dynamics in molecular Rydberg states. Using Rydberg states as intermediates simplifies the spectra by removing the vibrational components, while their structural sensitivity brings out important features of ultrafast molecular dynamics. The transition from the intermediate Rydberg state to the ion state gives rise to sharp peaks, forming the basis of Rydberg fingerprint spectroscopy (RFS). The time-resolved RFS, complemented with the theoretical calculations, provide an almost complete two-dimensional picture of the structural dynamics of the model systems. The model systems we choose to study different aspects of structural dynamics are: Triethylamine and N,N,N’,N’-Tetramethylethyl-enediamine for conformational dynamics; N,N’-Dimethylpiperazine, N-methylmor-pholine and related molecules for charge transfer dynamics; and N,N’-Dimethyliso propylamine and N,N,N’,N’-Tetramethylethylene -diamine for cluster dynamics and proton transfer.
DEB, SANGHAMITRA,
"Ultrafast structural dynamics of flexible, Rydberg excited molecular systems"
(2012).
Chemistry Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0GH9G7X
