Emeritus ProfessorLeszek Frasinski
Distinguished Research Fellow
Department of Physics - Faculty of Natural Sciences
Orcid identifier0000-0001-9308-4925 (opens in a new tab)
- Distinguished Research FellowDepartment of Physics - Faculty of Natural Sciences
- 206, Blackett Laboratory, South Kensington Campus, United Kingdom
RESEARCH
My research seeks fundamental understanding the electron dynamics of the molecular bond. While this is a curiosity-driven pursuit, the applications are expected to follow, because molecular dynamics is the key mechanism in chemistry, biology and medicine.
This research direction crystallized in my mind over 40 years ago, when I was looking at fragmentation dynamics of molecular oxygen revealed in a new experimental technique we devised for synchrotron radiation studies at the Daresbury Laboratory. On a noisy map of electron-ion coincidences I could see quite clearly the nuclear motion of the molecule, but the electronic motion remained unresolved.
To probe the electrons, we moved our experiments to the Rutherford Appleton Laboratory, where short, intense laser pulses were available. With high laser intensities, we have discovered new phenomena: multielectron dissociative ionisation, bond hardening, and counterintuitive alignment. To understand these mechanisms, we have developed a field-ionisation Coulomb-explosion model that assumed a simplified behaviour of electrons.
The experimental studies of molecular dynamics in intense laser fields have been substantially aided by the technique of covariance mapping, which I have developed as a generalisation of the earlier coincidence maps. The development and applications of covariance mapping has become the primary area of my scientific expertise.
When laser-generated pulses of light were shortened to the attosecond timescale at the beginning of this century, a direct probing of the electron dynamics became possible. My initial work in this area started from elucidating and the key mechanisms of attosecond pulse generation such as synchronisation of high harmonics and progressed to controlling the attosecond emission.
The construction of powerful free-electron lasers has provided us with very intense x-ray pulses we use to probe the electron dynamics in inner shells of atoms and molecules. To reveal electron correlations the experimental technique has been extended to partial covariance mapping.
While covariance maps carry substantially more information than one-dimensional spectra, the maps show only pair-wise correlations. To correlate three, four, or even more fragments, I have generalised the technique to cumulant mapping, which processes statistical information in a multidimensional space.
Such multidimensional capabilities of cumulants may shed light on how natural intelligence works. I am currently exploring this problem within the School of Human and Artificial Intelligence.
This research direction crystallized in my mind over 40 years ago, when I was looking at fragmentation dynamics of molecular oxygen revealed in a new experimental technique we devised for synchrotron radiation studies at the Daresbury Laboratory. On a noisy map of electron-ion coincidences I could see quite clearly the nuclear motion of the molecule, but the electronic motion remained unresolved.
To probe the electrons, we moved our experiments to the Rutherford Appleton Laboratory, where short, intense laser pulses were available. With high laser intensities, we have discovered new phenomena: multielectron dissociative ionisation, bond hardening, and counterintuitive alignment. To understand these mechanisms, we have developed a field-ionisation Coulomb-explosion model that assumed a simplified behaviour of electrons.
The experimental studies of molecular dynamics in intense laser fields have been substantially aided by the technique of covariance mapping, which I have developed as a generalisation of the earlier coincidence maps. The development and applications of covariance mapping has become the primary area of my scientific expertise.
When laser-generated pulses of light were shortened to the attosecond timescale at the beginning of this century, a direct probing of the electron dynamics became possible. My initial work in this area started from elucidating and the key mechanisms of attosecond pulse generation such as synchronisation of high harmonics and progressed to controlling the attosecond emission.
The construction of powerful free-electron lasers has provided us with very intense x-ray pulses we use to probe the electron dynamics in inner shells of atoms and molecules. To reveal electron correlations the experimental technique has been extended to partial covariance mapping.
While covariance maps carry substantially more information than one-dimensional spectra, the maps show only pair-wise correlations. To correlate three, four, or even more fragments, I have generalised the technique to cumulant mapping, which processes statistical information in a multidimensional space.
Such multidimensional capabilities of cumulants may shed light on how natural intelligence works. I am currently exploring this problem within the School of Human and Artificial Intelligence.