Periodic Reporting for period 2 - RadSpec (A New Strategy for Vibronic Spectroscopy of Radicals)
Período documentado: 2022-03-01 hasta 2023-08-31
Free radicals are reactive molecules with unpaired electrons. This open shell electronic configuration makes them notoriously difficult to study. As reactive intermediates, they are usually short lived and very seldom isolated, and their quantum mechanical behavior is challenging. The EU-funded RadSpec project aims to provide answers to longstanding questions about the quantum mechanical and chemical behavior of both known and unknown reactive intermediates using vibronic spectroscopy methods. Project results are expected to significantly impact on a number of fields including combustion, atmospheric chemistry, polymerisation, plasma chemistry, biochemistry, and many other chemical processes.
This proposal aims to develop a novel strategy for high resolution vibronic spectroscopy of radicals, with
unprecedented sensitivity, specificity, and applicability. The proposed scheme will provide answers to
longstanding quantum mechanical questions about non-adiabatic dynamics, and, in combination with a
unique, recently developed transparent microreactor source of reactive molecules, enable the pursuit of
unknown reactive intermediates.
Radicals and transient reactive intermediates are centrally important to chemistry but notoriously difficult
to study. The proposer has recently led several successful experimental and theoretical efforts directed
at molecules and transition states thought to be extremely difficult if not impossible to characterize. Here
we propose to launch a revolutionary approach to spectroscopy of these important species, exploiting a
key insight into dissociation dynamics on top of elements of state of the art laser spectroscopy techniques
in the infrared, ultraviolet, and vacuum ultraviolet to forge a new universal method. It possesses the high
sensitivity and mass selectivity of ion detection, while simultaneously being multidimensional and fully
rovibronic in scope to extract the maximum possible information about coupled nuclear and electronic
dynamics.
We anticipate that this advance will also be of great interest and utility to a broad swath of researchers
in related fields, such as combustion, atmospheric chemistry, and surface science, who require the ability
to track rare but reactive species. The nitrate and cyclopentadienyl radicals will initially be targeted as
particularly important examples, and we also plan to hunt for as yet unobserved reactive intermediates
using our new spectroscopic scheme alongside the flexibility of our molecular source to rationally explore
chemical phase space.
This proposal aims to develop a novel strategy for high resolution vibronic spectroscopy of radicals, with
unprecedented sensitivity, specificity, and applicability. The proposed scheme will provide answers to
longstanding quantum mechanical questions about non-adiabatic dynamics, and, in combination with a
unique, recently developed transparent microreactor source of reactive molecules, enable the pursuit of
unknown reactive intermediates.
Radicals and transient reactive intermediates are centrally important to chemistry but notoriously difficult
to study. The proposer has recently led several successful experimental and theoretical efforts directed
at molecules and transition states thought to be extremely difficult if not impossible to characterize. Here
we propose to launch a revolutionary approach to spectroscopy of these important species, exploiting a
key insight into dissociation dynamics on top of elements of state of the art laser spectroscopy techniques
in the infrared, ultraviolet, and vacuum ultraviolet to forge a new universal method. It possesses the high
sensitivity and mass selectivity of ion detection, while simultaneously being multidimensional and fully
rovibronic in scope to extract the maximum possible information about coupled nuclear and electronic
dynamics.
We anticipate that this advance will also be of great interest and utility to a broad swath of researchers
in related fields, such as combustion, atmospheric chemistry, and surface science, who require the ability
to track rare but reactive species. The nitrate and cyclopentadienyl radicals will initially be targeted as
particularly important examples, and we also plan to hunt for as yet unobserved reactive intermediates
using our new spectroscopic scheme alongside the flexibility of our molecular source to rationally explore
chemical phase space.
In the first half of the project we initiated the development of a new spectroscopic strategy for radicals and contributed new discoveries on the properties of fundamental radicals. We have constructed experimental apparatus for the production of radicals under vacuum conditions, compatible with laser spectroscopy and sensitive, multiplexed detection by time of flight mass spectrometry. We have integrated multiple laser systems spanning the infrared, visible, ultraviolet, and vacuum ultraviolet spectral regions. Production of synthetic precursors for central radical target species is also well underway. Studies at two synchrotrons (SOLEIL and the Swiss Light Source) have yielded valuable results on the cyclopropyl and ethyl radicals, including inspiring a new theoretical method for simulation of absorption spectra.
The studies published in the first half of the project have advanced fundamental knowledge in pericyclic systems, as well as raised a new perspective on the nature of transition states compared to stable species, combined with a novel capability for accurate simulation of absorption spectra. We anticipate that the remainder of the project will yield additional data on fundamental reactive species as well as broadly applicable new techniques for their study.