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Spatio-temporal resolution studies on a highly compact ultrafast electron diffractometer
(2015)
Time-resolved diffraction with femtosecond electron pulses has become a promising technique to directly provide insights into photo induced primary dynamics at the atomic level in molecules and solids. Ultrashort pulse duration as well as extensive spatial coherence are desired, however, space charge effects complicate the bunching of multiple electrons in a single pulse.Weexperimentally investigate the interplay between spatial and temporal aspects of resolution limits in ultrafast electron diffraction (UED) on our ...
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Detecting ultrafast interatomic electronic processes in media by fluorescence
(In: New journal of physics. - London : IOP, 2014, 16, 102002, 1-9, 2014)
Interatomic coulombic decay (ICD), a radiationless transition in weakly bonded systems, such as solutes or van der Waals bound aggregates, is an effective source for electrons of low kinetic energy. So far, the ICD processes could only be probed in ultra-high vacuum by using electron and/or ion spectroscopy. Here we show that resonant ICD processes can also be detected by measuring the subsequently emitted characteristic fluorescence radiation, which makes their study in dense media possible.
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Asymptotic model for shape resonance control of diatomics by intense non-resonant light: universality in the single-channel approximation
(2015)
Non-resonant light interacting with diatomics via the polarizability anisotropy couples different
rotational states and may lead to strong hybridization of the motion. The modification of shape
resonances and low-energy scattering states due to this interaction can be fully captured by an
asymptotic model, based on the long-range properties of the scattering (Crubellier et al 2015 New J.
Phys. 17 045020). Remarkably, the properties of the field-dressed shape resonances in this asymptotic
multi-channel description ...
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Asymptotic model for shape resonance control of diatomics by intense non-resonant light
(2015)
We derive a universal model for atom pairs interacting with non-resonant light via the polarizability
anisotropy, based on the long range properties of the scattering. The corresponding dynamics can be
obtained using a nodal line technique to solve the asymptotic Schrödinger equation. It consists of
imposing physical boundary conditions at long range and vanishing the wavefunction at a position
separating the inner zone and the asymptotic region. We show that nodal lines which depend on the
intensity of the ...
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Femtosecond wavepacket interferometry using the rotational dynamics of a trapped cold molecular ion
(2015)
A Ramsey-type interferometer is suggested, employing a cold trapped ion and two time-delayed offresonant
femtosecond laser pulses. The laser light couples to the molecular polarization anisotropy,
inducing rotational wavepacket dynamics. An interferogram is obtained from the delay dependent
populations of the final field-free rotational states. Current experimental capabilities for cooling and
preparation of the initial state are found to yield an interferogram visibility of more than 80%. The
interferograms can ...
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Squeezed thermal phonons precurse nonthermal melting of silicon as a function of fluence
(2013)
A femtosecond-laser pulse can induce ultrafast nonthermal melting of various materials along pathways
that are inaccessible under thermodynamic conditions, but it is not known whether there is any structural
modification at fluences just below the melting threshold. Here, we show for silicon that in this regime the
room-temperature phonons become thermally squeezed, which is a process that has not been reported
before in this material. We find that the origin of this effect is the sudden femtosecond-laser-induc ...
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Discriminatory resonance energy transfer mediated by a chiral environment
(2024-05-07)
In this study, we delve into the crucial influence of and enhancement by chiral environments on the discriminatory capabilities of resonance energy transfer. Firstly, we scrutinize the impact of a macroscopic chiral medium enveloping the interacting molecules; secondly, we probe the effect of a chiral mediating molecule in close proximity to the system. Importantly, our findings demonstrate that chiral environments not only modulate pre-existing discriminatory effects but also introduce novel mechanisms for discrimination. ...
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Nondipolar photoelectron angular distributions from fixed-in-space N₂ molecules
(2024-06-26)
We investigate experimentally and theoretically the N 1s photoionization of fixed-in-space N2 molecules at a photon energy of 880 eV. In our experiment, we employed circularly polarized synchrotron radiation for the photoionization and coincident electron and fragment-ion detection using cold target recoil ion momentum spectroscopy. The accompanying angle-resolved calculations were carried out by the multichannel single-center method and code within the frozen-core Hartree–Fock approximation. The computed emission ...