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Tracing orbital images on ultrafast time scales
R Wallauer1, M Raths2,3,4, K Stallberg1
1Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität Marburg, Renthof 5, 35032 Marburg, Germany.
Science (New York, N.Y.)
|February 19, 2021
Summary
Researchers imaged unoccupied molecular orbitals in momentum space using ultrafast laser pulses. This breakthrough allows observing electron dynamics and orbital shapes in real-time, advancing molecular science.
Area of Science:
- Quantum Chemistry
- Molecular Spectroscopy
- Ultrafast Dynamics
Background:
- Frontier orbitals govern molecular properties and reactivity.
- Imaging occupied orbitals in momentum space is possible via photoemission tomography.
- Real-time dynamics of unoccupied orbitals remain experimentally elusive.
Purpose of the Study:
- To develop a method for imaging unoccupied molecular orbitals in momentum space over time.
- To connect excited-state dynamics to real-space excitation pathways.
- To enable observation of ultrafast electron motion.
Main Methods:
- Combined time-resolved photoemission with high laser harmonics.
- Utilized a momentum microscope for tomographic imaging.
- Performed femtosecond pump-probe experiments on transiently excited electrons.
Main Results:
- Successfully measured the full momentum-space distribution of transiently excited electrons.
- Established a tomographic, femtosecond pump-probe technique for unoccupied orbitals.
- Linked excited-state dynamics to real-space excitation pathways.
Conclusions:
- The developed method allows real-time observation of unoccupied molecular orbital dynamics.
- This technique provides insights into ultrafast electron motion and molecular excitation.
- Future applications may include observing electron motion in time and space.
