Photoelectron and ion imaging of ultrafast dynamics in controlled complex molecules

We are currently setting up an experiment to study the dynamics of rearrangement processes in moderately complex organic molecules. The molecules are quantum state selected by an electric deflector and fixed in space via strong laser pulses and dc electric fields. The electronic and nuclear structures and dynamics of these samples are investigated using femtosecond photoelectron imaging.

Within the DFG priority program 1840 "Quantum Dynamics in Tailored Intense Fields" (QUTIF) we have a related collaborative project LIEDOM.

Molecular Frame photoelectron angular distributions

We have exploited strongly 3D oriented samples of the prototypical asymmetric top molecule benzonitrile to obtain molecular frame photoelectron angular distributions of molecule fixed in space.

Lotte Holmegaard, Jonas L. Hansen, Line Kalhøj, Sofie Louise Kragh, Henrik Stapelfeldt, Frank Filsinger, Jochen Küpper, Gerard Meijer, Darko Dimitrovski, Mahmoud Abu-samha, Christian P. J. Martiny, and Lars Bojer Madsen
Photoelectron angular distributions from strong-field ionization of oriented molecules
Nat. Phys. 6 (2010), 428

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Timepix3: single-pixel multi-hit energy-measurement behaviour

13 November 2024

The event-driven hybrid-pixel detector readout chip, Timepix3, has the ability to simultaneously measure the time of an event on the nanosecond timescale and the energy deposited in the sensor. However, the behaviour of the system when two events are recorded in quick succession of each other on the same pixel was not studied in detail previously. We present experimental measurements, circuit simulations, and an empirical model for the impact of a preceding event on this energy measurements, which can result in a loss as high as 70%. Accounting for this effect enables more precise compensation, particularly for phenomena like timewalk. This results in significant improvements in time resolution — in the best case, multiple tens of nanoseconds — when two events happen in rapid succession.

Keynote lecture at Sino-German Physics Conference

20 October 2024

Jochen presented a keynote lecture on CMI research at the 33rd Annual Meeting of the Chinese Society of Physicists in Germany (GCPD) in Jinan, Shadong, China. The lecture was well attained locally and, according to the organizers, followed by more than 10,000 people in the koushare online stream.

Recent Publications