Publications de Marcel Drabbels

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Excitation spectra up to the ionization threshold are reported for barium atoms located on the surface of helium nanodroplets. For states with low principal quantum number, the resonances are substantially broadened and shifted towards higher energy with r ...

An apparatus for observing dynamic systems by time-resolved microscopy has an optical microscope including a cryo stage for receiving a cryo sample and maintaining the cryo sample at a cryogenic temperature, a heating system configured to temporarily heat at least a portion of the cryo sample such that the portion of the cryo sample melts to a liquid state, temporarily resides in the liquid state, and then revitrifies, and an image detector associated with the optical microscope for detecting magnified imag

The dynamics of laser-excited sodium atoms at the surface of helium nanodroplets has been investigated as a function of quantum state. For all cases excitation of the system leads to desorption of the sodium atom from the droplet surface. The mean kinetic ...

The preparation of cryo-EM samples by soft-landing mass spectrometry promises to significantly simplify sample optimization, which has remained an important bottleneck in single-particle cryo-electron microscopy (cryo-EM). However, only compacted configurations are observed after soft-landing since the proteins are dehydrated in the process. Here, we demonstrate that proteins can be returned to their native state by depositing a layer of amorphous ice and briefly flash melting the sample to rehydrate the so

A generally accepted understanding of the anomalous properties of water will only emerge if it becomes possible to systematically characterize water in the deeply supercooled regime, from where the anomalies appear to emanate. This has largely remained elu ...

One- and two-photon excitation spectra of sodium atoms on the surface of helium droplets are reported. The spectra are recorded by monitoring the photoionization yield of desorbed atoms as function of excitation frequency. The excitation spectra involving ...

We present a joint experimental and theoretical study on the desolvation of Ba+ cations in 4He nanodroplets excited via the 6p 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba+ cations and Ba+Hen exciplexes wit ...

High resolution IR spectra of aniline, styrene and 1,1-diphenylethylene cations embedded in superfluid helium nanodroplets have been recorded in the 300-1700 cm-1 range using the free-electron laser FELIX as radiation source. Comparison of the spectra with ...

Relative state-to-state cross sections for inelastic collisions between NO X (2) Pi(1/2) (upsilon = 20, J = 0.5, e or f) and He have been determined in a crossed molecular beam setup at a collision energy of 195 cm(-1). Efficient initial state preparation of the NO molecules is achieved by stimulated emission pumping by way of the NO B (2) Pi(1/2) (upsilon = 5) state. The rotational state distribution of the inelastically scattered NO molecules is probed by laser induced fluorescence through the A (2) Sigma

We report on the first successful high-resolution spectroscopic studies on isolated para-coumaric acid, the chromophore of the photoactive yellow protein which has become a model system for studying biological light induced signal transduction. Employing v ...

In this manuscript, we describe a simple and accurate method for finding the temporal overlap of the laser pump and electron probe pulse in ultrafast TEM. Our approach is based on the observation that the outline of a nanoparticle blurs at time zero, a phe ...

A microsecond time-resolved version of cryo-electron microscopy (cryo-EM) has recently been introduced to enable observation of the fast conformational motions of proteins. The technique involves locally melting a cryo sample with a laser beam to allow the ...

Excitation spectra of the and transitions of aniline cations embedded in helium nanodroplets are reported. The spectra are characterized by broad asymmetric resonances that consist of an intrinsically broadened zero-phonon line which partially overlaps wit ...

Microsecond time-resolved cryo-electron microscopy promises to significantly advance our understanding of protein function by rendering cryo-electron microscopy (cryo-EM) fast enough to observe proteins at work. This emerging technique involves flash melting a cryo sample with a laser beam to provide a brief time window during which dynamics are initiated. When the laser is switched off, the sample revitrifies, arresting the proteins in their transient configurations. However, observations have so far been

Preferred particle orientation remains a frequently encountered issue in cryo-electron microscopy that arises when proteins adsorb to the air-water interface in only a limited number of orientations. This can significantly increase the data acquisition time required to reach a desired resolution or even make it impossible to obtain a reconstruction altogether. Here, we show that preferred orientation can be overcome by continuously exciting the sample with ultrasonic waves during vitrification. Our experime

The recombination of fragments resulting from the photodissociation of (fluorinated) alkyl iodides in helium nanodroplets at a wavelength of 266 nm has been investigated by means of ion imaging techniques. It is found that in the case of CH3I an appreciabl ...

Infrared spectroscopy provides a means to determine the intrinsic geometrical structures of molecules. Here we present a novel spectroscopic method that uses superfluid helium nanodroplets to record IR spectra of cold molecular ions, in this particular cas ...

Thanks to their high brightness, field emitters are the electron sources of choice in most high-end electron microscopes. Under typical operating conditions, the available emission current from these emitters is largely limited by practical considerations, ...

The dynamics following the photoionization of neutral Rb and Cs atoms residing in a dimple at the surface of a superfluid 4He1000 nanodroplet has been investigated within time-dependent density functional theory, complementing a previous study on Ba. The c ...

High intensity XUV radiation from a free-electron laser (FEL) was used to create a nanoplasma inside ammonia clusters with the intent of studying the resulting electron-ion interactions and their interplay with plasma evolution. In a plasma-like state, ele ...

Marcel Drabbels

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Spectroscopy and Dynamics of Barium-doped Helium Nanodroplets

Microsecond melting and revitrification of cryo samples with a correlative light electron microscopy setup

Dynamics of Excited Sodium Atoms Attached to Helium Nanodroplets

Cryo-EM Sample Preparation with Soft-Landing and Laser Flash Melting

Electron diffraction of deeply supercooled water in no man’s land

Spectroscopy on Rydberg states of sodium atoms on the surface of helium nanodroplets

Dynamics of photoexcited Ba+ cations in 4He nanodroplets

Mid-Infrared Spectroscopy of Molecular Ions in Helium Nanodroplets

Parity-resolved state-to-state cross sections for inelastic scattering of NO X (2)Pi(1/2) (upsilon = 20, J = 0.5, elf) from He: A comparison between crossed molecular beams experiments and ab initio theory

High-resolution excitation and absorption spectroscopy of gas-phase p-coumaric acid: unveiling an elusive chromophore

Accurate time zero determination in an ultrafast transmission electron microscope without energy filter

Near-atomic resolution reconstructions from in situ revitrified cryo samples

Electronic Spectroscopy of Aniline Ions Embedded in Helium Nanodroplets

Ultrathin Liquid Cells for Microsecond Time-Resolved Cryo-EM

Overcoming Preferred Orientation in Cryo-EM With Ultrasonic Excitation During Vitrification

Photodissociation of Alkyl Iodides in Helium Nanodroplets III: Recombination

IR spectroscopy of molecular ions by nonthermal ion ejection from helium nanodroplets

Intense microsecond electron pulses from a Schottky emitter

Picosecond solvation dynamics of alkali cations in superfluid 4He nanodroplets

Time-resolved formation of excited atomic and molecular states in XUV-induced nanoplasmas in ammonia clusters