Periodic Reporting for period 2 - TOMATTO (The ultimate Time scale in Organic Molecular opto-electronics, the ATTOsecond)
Okres sprawozdawczy: 2022-10-01 do 2024-03-31
Photoinduced electron transfer (ET) and charge transfer (CT) processes occurring in organic materials are the cornerstone of technologies aiming at the conversion of solar energy into electrical energy and at its efficient transport. Thus, investigations of ET/CT induced by visible (VIS) and ultraviolet (UV) light are fundamental for the development of more efficient organic opto-electronic materials. The usual strategy to improve efficiency is chemical modification, which is based on chemical intuition and try-and-error approaches, with no control on the ultrafast electron dynamics induced by light. Achieving the latter is not easy, as the natural time scale for electronic motion is the attosecond (10^-18 seconds). In this project we propose to overcome the current time-scale bottleneck and get direct information on the early stages of ET/CT generated by VIS and UV light absorption on organic opto-electronic systems by extending the tools of attosecond science beyond the state of the art and combining them with the most advanced methods of organic synthesis and computational modelling. The objective is to provide clear-cut movies of ET/CT with unprecedented time resolution and with the ultimate goal of engineering the molecular response to optimize the light driven processes leading to the desired opto-electronic behaviour.
1. We have installed and tested an optical parametric amplifier (OPA) for the generation of femtosecond pulses, tunable in the range 1.1-2.6 μm.
2. We have generated deep UV(DUV) and UV pulses, tunable in the spectral range 200-350 nm by employing the resonant dispersive wave (RDW) emission process, with a minimum pulse duration of 2.4 fs at the central wavelength of 350 nm.
3. An UV/XUV pump-probe setup with femtosecond temporal resolution has been developed to acquire the necessary experience for the development of the attosecond UV/XUV beamline.
4. We have developed the necessary synthetic methodologies to replace the benzene ring in paranitroanilines by other aromatic heterocyclic cores, thiophene and furane, with different resonance energies.
5. Synthesis and structural characterizations of five novel butterfly-shaped emitters and chiral nanographenes have been accomplished.
6. We have completed parallelization of the quantum chemistry part of the computer package XChem, which is available as open source at https://doi.org/10.21950/GHWTML and at the AMOS gateway (https://amosgateway.org/).
7. We have developed a time dependent version of XCHEM that incorporates the effect of nuclear motion in a full quantum mechanical way and the coupling of this motion with the electronic one.
8. We have used the above code to evaluate N2 photoionization delays in the vicinity of resonant states, where the coupling between electronic and nuclear motions cannot be ignored. Our results have allowed us to interpret one of the earliest experiments ever performed in molecules.
9. Experiments have been performed by applying the currently existing attosecond beamline in Milano to donor-acceptor systems. We have investigated charge dynamics following prompt photoionization in nitroaniline molecules in gas phase. Numerical simulations reveal that the observed transient features are related to a sub-10-fs non-adiabatic charge transfer process, followed by longer (~ 35 fs) relaxation dynamics associated with the spreading of the nuclear wave packet along the molecular degrees of freedom.
10. Antiaromatic units have been introduced in polycyclic hydrocarbons (PHs) via thermally selective intra- and intermolecular ring-rearrangement reactions of dibromomethylene-functionalized molecular precursors upon sublimation on a hot Au(111) metal surface, not available in solution chemistry.
2. We have generated deep UV(DUV) and UV pulses, tunable in the spectral range 200-350 nm by employing the resonant dispersive wave (RDW) emission process, with a minimum pulse duration of 2.4 fs at the central wavelength of 350 nm.
3. An UV/XUV pump-probe setup with femtosecond temporal resolution has been developed to acquire the necessary experience for the development of the attosecond UV/XUV beamline.
4. We have developed the necessary synthetic methodologies to replace the benzene ring in paranitroanilines by other aromatic heterocyclic cores, thiophene and furane, with different resonance energies.
5. Synthesis and structural characterizations of five novel butterfly-shaped emitters and chiral nanographenes have been accomplished.
6. We have completed parallelization of the quantum chemistry part of the computer package XChem, which is available as open source at https://doi.org/10.21950/GHWTML and at the AMOS gateway (https://amosgateway.org/).
7. We have developed a time dependent version of XCHEM that incorporates the effect of nuclear motion in a full quantum mechanical way and the coupling of this motion with the electronic one.
8. We have used the above code to evaluate N2 photoionization delays in the vicinity of resonant states, where the coupling between electronic and nuclear motions cannot be ignored. Our results have allowed us to interpret one of the earliest experiments ever performed in molecules.
9. Experiments have been performed by applying the currently existing attosecond beamline in Milano to donor-acceptor systems. We have investigated charge dynamics following prompt photoionization in nitroaniline molecules in gas phase. Numerical simulations reveal that the observed transient features are related to a sub-10-fs non-adiabatic charge transfer process, followed by longer (~ 35 fs) relaxation dynamics associated with the spreading of the nuclear wave packet along the molecular degrees of freedom.
10. Antiaromatic units have been introduced in polycyclic hydrocarbons (PHs) via thermally selective intra- and intermolecular ring-rearrangement reactions of dibromomethylene-functionalized molecular precursors upon sublimation on a hot Au(111) metal surface, not available in solution chemistry.
We have generated sub-3-fs pulses, tunable in a broad spectral region in the DUV and UV, with energy in the μJ range. These pulses will be used in an attosecond beamline, which will be implemented to measure electron dynamics in donor-acceptor molecules, in combination with advanced theoretical calculations, thus providing a novel and intuitive way of looking at ultrafast dynamics in neutral molecules. This will shed new light on the role played by electronic-nuclear coupling in donor-acceptor systems in response to electronic excitation.
We have built the TOMATTO supercomputer, containing more than 1,500 cores with last generation processors, interconnected with the most advanced cabling, which will be crucial to run parallel calculations in an MPI environment. This will allow for massive production of results by using our codes. Among the latter, we have developed an extension of the XCHEM code that allows us to describe the coupled electron and nuclear dynamics in many-electron molecules in full dimensionality and in a full quantum mechanical way, which goes well beyond the state of the art in this field. The new methodology has been successfully applied to N2, providing a complete understanding of the unusual behavior of electrons in the vicinity of resonances due to their coupling with nuclear motion. The new methodology will open the way to treat donor acceptor molecules as those considered in TOMATTO, after performing the necessary approximations.
Once the new equipment will be settled down in Milano, experiments on neutral molecules (and not ionised as it has been done so far) will be carried out on the molecules synthesized at UCM and theoretically studied at IMDEA/UAM. The expectations at the attosecond time scale are still intact since this study will be undertaken for the first time on non-ionized molecules. Therefore, significant achievements as breakthroughs or as advancing a research field significantly beyond the state of the art are expected. It is worth mentioning that, along this first period of 24 months, the facilities have been established and the molecules designed and synthesized.
We have built the TOMATTO supercomputer, containing more than 1,500 cores with last generation processors, interconnected with the most advanced cabling, which will be crucial to run parallel calculations in an MPI environment. This will allow for massive production of results by using our codes. Among the latter, we have developed an extension of the XCHEM code that allows us to describe the coupled electron and nuclear dynamics in many-electron molecules in full dimensionality and in a full quantum mechanical way, which goes well beyond the state of the art in this field. The new methodology has been successfully applied to N2, providing a complete understanding of the unusual behavior of electrons in the vicinity of resonances due to their coupling with nuclear motion. The new methodology will open the way to treat donor acceptor molecules as those considered in TOMATTO, after performing the necessary approximations.
Once the new equipment will be settled down in Milano, experiments on neutral molecules (and not ionised as it has been done so far) will be carried out on the molecules synthesized at UCM and theoretically studied at IMDEA/UAM. The expectations at the attosecond time scale are still intact since this study will be undertaken for the first time on non-ionized molecules. Therefore, significant achievements as breakthroughs or as advancing a research field significantly beyond the state of the art are expected. It is worth mentioning that, along this first period of 24 months, the facilities have been established and the molecules designed and synthesized.