Laser spectroscopy of isolated molecules and systems: structure, dynamics and analysis

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This proposal requests funds to extend and expand a program of NSERC sponsored research in basic and applied molecular spectroscopy. Research in physical chemistry at the interface with molecular physics will use pulsed laser radiation, tuned in multiresonant excitation sequences, to investigate the relaxation dynamics of superexcited small molecules - in isolation and in cold ensembles. Here, we will work spectroscopically to study the coupling of the orbital energy and angular momentum of state-selected extravalent electrons with the rovibrionic degrees of freedom of isolated molecular cations. We will maintain a focus on an important set of energetic, open-shell polyatomic free-radical intermediates with the objective of characterizing excited-state structure and dynamics. By charting rovibronic positions and lineshapes, we will obtain experimental information on electron-cation scattering for comparison with theory. Other experiments will extend further to study the nonadiabatic intermolecular scattering dynamics by which a gas of state-selected high-Rydberg molecules relaxes to form a cold plasma. We have succeeded in establishing conditions under which such a transformation occurs in NO. New work employing spatial and velocity map imaging techniques together with spectroscopic probes in the THz frequency domain will explore multiscale structural and dynamical manifestations of this quantum phase transition. Our research in analytical chemistry will explore novel instrumental and informatics methodologies that facilitate the application of Raman spectroscopy for multivariate materials classification in contexts ranging from industrial process monitoring to molecular biology. Research using dynamic alignment by means of actuated objectives will enable us to devise new mapping and spatial averaging approaches. We will develop and characterize powerful multivariate classification algorithms to enable us to track subtle spectral variations with the aim of isolating targeted signatures in the presence of uncorrelated variance. Information processing will extend to incorporate bright-field optical cues to establish new chemometrically driven smart-scanning modalities.