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Ulrich Lorenz

Cette personne a quitté l’EPFL

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Publications associées (28)

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High-Resolution Transmission Electron Microscopy with Bright Microsecond Electron Pulses

Marcel Drabbels, Ulrich Lorenz, Pavel Olshin, Gabriele Bongiovanni

Transmission electron microscopy at atomic-resolution is a crucial tool in a variety of fields, ranging from materials science to biology. [1,2] Fast electron cameras have recently enabled high-speed observations atomic resolution. [3] Moreover, they have ...

2021

IR spectroscopy of isolated metal-organic complexes of biocatalytic interest: Evidence for coordination number four for Zn2+(imidazole)(4)

Ulrich Lorenz

The characterization of the interactions of Zn2+ ions with imidazole ligands is vital for understanding the function of a plethora of zinc enzymes at the molecular level. The infrared multiple photon dissociation (IRMPD) spectrum of mass selected Zn2+(imid ...

2011

Microsecond melting and revitrification of cryo samples

Marcel Drabbels, Ulrich Lorenz, Pavel Olshin, Jonathan Mark Voss, Oliver Florian Harder

The dynamics of proteins that are associated with their function typically occur on the microsecond timescale, orders of magnitude faster than the time resolution of cryo-electron microscopy. We have recently introduced a novel approach to time-resolved cr ...

AIP Publishing2021

Characterization of a time-resolved electron microscope with a Schottky field emission gun

Marcel Drabbels, Ulrich Lorenz, Pavel Olshin

The rapid growth of the field of time-resolved and ultrafast electron microscopy has been accompanied by the active development of new instrumentation. Recently, time-resolved microscopes equipped with a field emission gun have been introduced, demonstrati ...

2020

Spectroscopy of Cold, Biomolecular Ions : Instrumentation and Application

Ulrich Lorenz

In recent years, spectroscopic investigations of cold, biomolecular ions have started to provide new, detailed information about the structures of biomolecules in the gas phase. The present work comprises three major parts that describe the development of ...

EPFL2011

Atomic-Resolution Imaging of Fast Nanoscale Dynamics with Bright Microsecond Electron Pulses

Marcel Drabbels, Ulrich Lorenz, Pavel Olshin, Gabriele Bongiovanni

Atomic-resolution electron microscopy is a crucial tool to elucidate the structure of matter. Recently, fast electron cameras have added the time domain to high-resolution imaging, allowing static images to be acquired as movies from which sample drift can ...

American Chemical Society (ACS)2020

In Situ Observation of Coulomb Fission of Individual Plasmonic Nanoparticles

Romain Loïc Charbonnier, Marcel Drabbels, Ulrich Lorenz, Pavel Olshin, Jonathan Mark Voss

Reshaping plasmonic nanoparticles with laser pulses has been extensively researched as a tool for tuning their properties. However, in the absence of direct observations of the processes involved, important mechanistic details have remained elusive. Here, ...

2019

Structure of Zirconocene Complexes Relevant for Olefin Catalysis: Infrared Fingerprint of the Zr(C5H5)(2)(OH)(CH3CN)(+) Cation in the Gas Phase

Ulrich Lorenz

Cationic zirconocene complexes are active species in Ziegler-Natta catalysis for olefin polymerization. structure and metal-ligand bond strength strongly influence their activity. In the present work, the multiphoton dissociation (IRMPD) spectrum of mass s ...

2010

Spectroscopy of Protonated Peptides Assisted by Infrared Multiple Photon Excitation

Thomas Rizzo, Oleg Boyarkine, Ulrich Lorenz, Georgios Papadopoulos

We report here a new technique for spectroscopic studies of protonated, gas- phase biomolecules and demonstrate its utility by measuring highly-resolved electronic and infrared spectra of peptides of up to 17 amino acids. After UV excitation of an aromatic ...

2009

The fragmentation mechanism of gold nanoparticles in water under femtosecond laser irradiation

Marcel Drabbels, Ulrich Lorenz, Pavel Olshin, Gabriele Bongiovanni, Jonathan Mark Voss, Chengcheng Yan

Plasmonic nanoparticles in aqueous solution have long been known to fragment under irradiation with intense ultrafast laser pulses, creating progeny particles with diameters of a few nanometers. However, the mechanism of this process is still intensely deb ...

2021

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

Marcel Drabbels, Ulrich Lorenz, Gabriele Bongiovanni, Constantin Richard Krüger, Nathan Junior Mowry

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 ...

Nature Research2023

Structural Melting of an Amino Acid Dimer upon Intersystem Crossing

Thomas Rizzo, Ulrich Lorenz

We present a spectroscopic investigation of the excited-state dynamics of the phenylalanine (Phe)/serine (Ser) protonated dimer in the gas phase. Using an ultraviolet (UV) laser pulse, we promote individual isomers to the S1 state and probe their fate with ...

Amer Chemical Soc2014

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

Marcel Drabbels, Ulrich Lorenz, Pavel Olshin, Jonathan Mark Voss

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 ...

AIP American Institute of Physics2022

Near-atomic resolution reconstructions from in situ revitrified cryo samples

Marcel Drabbels, Ulrich Lorenz, Gabriele Bongiovanni, Jonathan Mark Voss, Oliver Florian Harder

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 ...

2023

A radio frequency/high voltage pulse generator for the operation of a planar multipole ion trap/time-of-flight mass spectrometer

Ulrich Lorenz, Severino Antonioni, Philippe Marmillod

We present a radio frequency (RF)/high voltage pulse generator designed to provide suitable waveforms for the operation of a planar multipole ion trap/time-of-flight mass spectrometer. Our generator supplies a RF signal to two pairs of trapping electrodes, ...

American Institute of Physics2013

Intense microsecond electron pulses from a Schottky emitter

Marcel Drabbels, Ulrich Lorenz, Pavel Olshin, Gabriele Bongiovanni

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, ...

AIP American Institute of Physics2020

Rapid melting and revitrification as an approach to microsecond time-resolved cryo-electron microscopy

Marcel Drabbels, Ulrich Lorenz, Pavel Olshin, Jonathan Mark Voss, Oliver Florian Harder

Proteins typically undergo dynamics on the microsecond to millisecond timescale, which is much faster than the time resolution of cryo-electron microscopy. Here, we propose a novel approach for microsecond time-resolved cryo-electron microscopy that involv ...

Elsevier2021

A new tandem mass spectrometer for photofragment spectroscopy of cold, gas-phase molecular ions

Thomas Rizzo, Oleg Boyarkine, Ulrich Lorenz, Annette Svendsen

We present here the design of a new tandem mass spectrometer that combines an electrospray ion source with a cryogenically cooled ion trap for spectroscopic studies of cold, gas-phase ions. The ability to generate large ions in the gas phase without fragme ...

American Institute of Physics2010

Multiple Isomers and Protonation Sites of the Phenylalanine/Serine Dimer

Thomas Rizzo, Ulrich Lorenz

Our investigation of the phenylalanine/serine (Phe/Ser) protonated dimer suggests that the intermolecular interaction between the two amino acids is more complex than could have been anticipated from previous studies of similar systems. Isomer-specific inf ...

2012

Fast viral dynamics revealed by microsecond time-resolved cryo-EM

Marcel Drabbels, Ulrich Lorenz, Oliver Florian Harder, Sarah Victoria Barrass

Observing proteins as they perform their tasks has largely remained elusive, which has left our understanding of protein function fundamentally incom- plete. To enable such observations, we have recently proposed a technique that improves the time resoluti ...

Nature Research2023