Here you will find all scientific publications from the group leader, Daniel Horke. Articles and materials written for a more general audience can be found on the Outreach pages. Recent posters from the group are in the gallery!
Filter Publications:
2022
9.
Abma G L, Kleuskens D, Wang S, Balster M, Roij A, Janssen N, Horke D A
Single-Color Isomer-Resolved Spectroscopy Journal Article
In: The Journal of Physical Chemistry A, vol. 126, pp. 3811–3815, 2022.
Abstract | Links | BibTeX | Altmetric | Tags: Control, electrostatic deflector, experimental design, Isomer-effects
@article{abmaSinglecolorIsomerresolvedSpectroscopy2022,
title = {Single-Color Isomer-Resolved Spectroscopy},
author = {Grite L. Abma and Dries Kleuskens and Siwen Wang and Michiel Balster and Andre Roij and Niek Janssen and Daniel A. Horke},
url = {https://doi.org/10.1021/acs.jpca.2c02277},
doi = {10.1021/acs.jpca.2c02277},
year = {2022},
date = {2022-06-01},
urldate = {2022-06-01},
journal = {The Journal of Physical Chemistry A},
volume = {126},
pages = {3811\textendash3815},
abstract = {Structural isomers, such as conformers or tautomers, are
of significant importance across chemistry and biology, as they can have
different functionalities. In gas-phase experiments using molecular
beams, formation of many different isomers cannot be prevented, and
their presence significantly complicates the assignment of spectral lines.
Current isomer-resolved spectroscopic techniques heavily rely on
theoretical calculations or make use of elaborate double-resonance
schemes. We show here that isomer-resolved spectroscopy can also be
performed using a single tunable laser. In particular, we demonstrate
single-color isomer-resolved spectroscopy by utilizing electrostatic
deflection to spatially separate the isomers. We show that for 3-
aminophenol we can spatially separate the syn and anti conformers and
use these pure samples to perform high-resolution REMPI spectroscopy, making the assignment of transitions to a particular isomer trivial, without any additional a priori information. This approach allows one to add isomer specificity to any molecular-beam-based experiment.},
keywords = {Control, electrostatic deflector, experimental design, Isomer-effects},
pubstate = {published},
tppubtype = {article}
}
Structural isomers, such as conformers or tautomers, are
of significant importance across chemistry and biology, as they can have
different functionalities. In gas-phase experiments using molecular
beams, formation of many different isomers cannot be prevented, and
their presence significantly complicates the assignment of spectral lines.
Current isomer-resolved spectroscopic techniques heavily rely on
theoretical calculations or make use of elaborate double-resonance
schemes. We show here that isomer-resolved spectroscopy can also be
performed using a single tunable laser. In particular, we demonstrate
single-color isomer-resolved spectroscopy by utilizing electrostatic
deflection to spatially separate the isomers. We show that for 3-
aminophenol we can spatially separate the syn and anti conformers and
use these pure samples to perform high-resolution REMPI spectroscopy, making the assignment of transitions to a particular isomer trivial, without any additional a priori information. This approach allows one to add isomer specificity to any molecular-beam-based experiment.
of significant importance across chemistry and biology, as they can have
different functionalities. In gas-phase experiments using molecular
beams, formation of many different isomers cannot be prevented, and
their presence significantly complicates the assignment of spectral lines.
Current isomer-resolved spectroscopic techniques heavily rely on
theoretical calculations or make use of elaborate double-resonance
schemes. We show here that isomer-resolved spectroscopy can also be
performed using a single tunable laser. In particular, we demonstrate
single-color isomer-resolved spectroscopy by utilizing electrostatic
deflection to spatially separate the isomers. We show that for 3-
aminophenol we can spatially separate the syn and anti conformers and
use these pure samples to perform high-resolution REMPI spectroscopy, making the assignment of transitions to a particular isomer trivial, without any additional a priori information. This approach allows one to add isomer specificity to any molecular-beam-based experiment.
2020
8.
Samanta A K, Amin M, Estillore A D, Roth N, Worbs L, Horke D A, Küpper J
Controlled Beams of Shock-Frozen, Isolated, Biological and Artificial Nanoparticles Journal Article
In: Structural Dynamics, vol. 7, no. 2, pp. 024304, 2020.
Abstract | Links | BibTeX | Altmetric | Tags: Control, experimental design, nanoparticles
@article{Samanta:StructuralDynamics7:024304,
title = {Controlled Beams of Shock-Frozen, Isolated, Biological and Artificial Nanoparticles},
author = {Amit K. Samanta and Muhamed Amin and Armando D. Estillore and Nils Roth and Lena Worbs and Daniel A. Horke and Jochen K\"{u}pper},
url = {https://aca.scitation.org/doi/10.1063/4.0000004},
doi = {10.1063/4.0000004},
year = {2020},
date = {2020-03-01},
urldate = {2020-07-21},
journal = {Structural Dynamics},
volume = {7},
number = {2},
pages = {024304},
publisher = {American Institute of Physics},
abstract = {X-ray free-electron lasers promise diffractive imaging of single molecules and nanoparticles with atomic spatial resolution. This relies on the averaging of millions of diffraction patterns of identical particles, which should ideally be isolated in the gas phase and preserved in their native structure. Here, we demonstrated that polystyrene nanospheres and Cydia pomonella granulovirus can be transferred into the gas phase, isolated, and very quickly shock-frozen, i.e., cooled to 4,K within microseconds in a helium-buffer-gas cell, much faster than state-of-the-art approaches. Nanoparticle beams emerging from the cell were characterized using particle-localization microscopy with light-sheet illumination, which allowed for the full reconstruction of the particle beams, focused to $<$100$mu$m$<$100,$mu$m$<$math display="inline" overflow="scroll" altimg="eq-00001.gif"$>$ $<$mrow$>$ $<$mo$>\&$lt;$<$/mo$>$ $<$mn$>$100$<$/mn$>$ $<$mo$>$,$<$/mo$>$ $<$mi$>mu<$/mi$>$ $<$mi mathvariant="normal"$>$m$<$/mi$><$/mrow$><$/math$>$, as well as for the determination of particle flux and number density. The experimental results were quantitatively reproduced and rationalized through particle-trajectory simulations. We propose an optimized setup with cooling rates for particles of few-nanometers on nanosecond timescales. The produced beams of shock-frozen isolated nanoparticles provide a breakthrough in sample delivery, e.g., for diffractive imaging and microscopy or low-temperature nanoscience.},
keywords = {Control, experimental design, nanoparticles},
pubstate = {published},
tppubtype = {article}
}
X-ray free-electron lasers promise diffractive imaging of single molecules and nanoparticles with atomic spatial resolution. This relies on the averaging of millions of diffraction patterns of identical particles, which should ideally be isolated in the gas phase and preserved in their native structure. Here, we demonstrated that polystyrene nanospheres and Cydia pomonella granulovirus can be transferred into the gas phase, isolated, and very quickly shock-frozen, i.e., cooled to 4,K within microseconds in a helium-buffer-gas cell, much faster than state-of-the-art approaches. Nanoparticle beams emerging from the cell were characterized using particle-localization microscopy with light-sheet illumination, which allowed for the full reconstruction of the particle beams, focused to $<$100$mu$m$<$100,$mu$m$<$math display="inline" overflow="scroll" altimg="eq-00001.gif"$>$ $<$mrow$>$ $<$mo$>&$lt;$<$/mo$>$ $<$mn$>$100$<$/mn$>$ $<$mo$>$,$<$/mo$>$ $<$mi$>mu<$/mi$>$ $<$mi mathvariant="normal"$>$m$<$/mi$><$/mrow$><$/math$>$, as well as for the determination of particle flux and number density. The experimental results were quantitatively reproduced and rationalized through particle-trajectory simulations. We propose an optimized setup with cooling rates for particles of few-nanometers on nanosecond timescales. The produced beams of shock-frozen isolated nanoparticles provide a breakthrough in sample delivery, e.g., for diffractive imaging and microscopy or low-temperature nanoscience.
2019
7.
Bieker H, Onvlee J, Johny M, He L, Kierspel T, Trippel S, Horke D A, Küpper J
Pure Molecular Beam of Water Dimer Journal Article
In: J. Phys. Chem. A, vol. 123, no. 34, pp. 7486–7490, 2019, ISSN: 1089-5639.
Abstract | Links | BibTeX | Altmetric | Tags: clusters, Control, electrostatic deflector, strong-field processes
@article{Bieker:J.Phys.Chem.A123:7486,
title = {Pure Molecular Beam of Water Dimer},
author = {Helen Bieker and Jolijn Onvlee and Melby Johny and Lanhai He and Thomas Kierspel and Sebastian Trippel and Daniel Alfred Horke and Jochen K\"{u}pper},
url = {https://doi.org/10.1021/acs.jpca.9b06460},
doi = {10.1021/acs.jpca.9b06460},
issn = {1089-5639},
year = {2019},
date = {2019-07-01},
urldate = {2019-08-07},
journal = {J. Phys. Chem. A},
volume = {123},
number = {34},
pages = {7486--7490},
abstract = {Spatial separation of water dimers from water monomers and larger water-clusters through the electric deflector is presented. A beam of water dimers with $93textasciitildetextbackslash%$ purity and a rotational temperature of $1.5textasciitilde$K was obtained. Following strong-field ionization using a 35textasciitilde fs laser pulse with a wavelength centered around 800textasciitilde nm and a peak intensity of $10^14textasciitildetextbackslash Wpcmcm$ we observed proton transfer and $46textasciitildetextbackslash%$ of ionized water dimers broke apart into hydronium ions textbackslash HHHOp and neutral OH.},
keywords = {clusters, Control, electrostatic deflector, strong-field processes},
pubstate = {published},
tppubtype = {article}
}
Spatial separation of water dimers from water monomers and larger water-clusters through the electric deflector is presented. A beam of water dimers with $93textasciitildetextbackslash%$ purity and a rotational temperature of $1.5textasciitilde$K was obtained. Following strong-field ionization using a 35textasciitilde fs laser pulse with a wavelength centered around 800textasciitilde nm and a peak intensity of $10^14textasciitildetextbackslash Wpcmcm$ we observed proton transfer and $46textasciitildetextbackslash%$ of ionized water dimers broke apart into hydronium ions textbackslash HHHOp and neutral OH.
2018
6.
Teschmit N, Horke D A, Küpper J
Spatially Separating the Conformers of a Dipeptide Journal Article
In: Angew. Chem. Int. Ed., vol. 57, pp. 13775–13779, 2018.
Links | BibTeX | Altmetric | Tags: Control, electrostatic deflector, Isomer-effects, Simulation
@article{Teschmit:Angew.Chem.Int.Ed.57:13775,
title = {Spatially Separating the Conformers of a Dipeptide},
author = {Nicole Teschmit and Daniel A. Horke and Jochen K\"{u}pper},
url = {https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201807646},
doi = {10.1002/anie.201807646},
year = {2018},
date = {2018-08-01},
journal = {Angew. Chem. Int. Ed.},
volume = {57},
pages = {13775--13779},
keywords = {Control, electrostatic deflector, Isomer-effects, Simulation},
pubstate = {published},
tppubtype = {article}
}
5.
Singh V, Samanta A K, Roth N, Gusa D, Ossenbrüggen T, Rubinsky I, Horke D A, Küpper J
Optimized Cell Geometry for Buffer-Gas-Cooled Molecular-Beam Sources Journal Article
In: Phys. Rev. A, vol. 97, no. 3, pp. 032704, 2018.
Abstract | Links | BibTeX | Altmetric | Tags: Control, experimental design
@article{Singh:Phys.Rev.A97:032704,
title = {Optimized Cell Geometry for Buffer-Gas-Cooled Molecular-Beam Sources},
author = {Vijay Singh and Amit K Samanta and Nils Roth and Daniel Gusa and Tim Ossenbr\"{u}ggen and Igor Rubinsky and Daniel A Horke and Jochen K\"{u}pper},
url = {https://link.aps.org/doi/10.1103/PhysRevA.97.032704},
doi = {10.1103/PhysRevA.97.032704},
year = {2018},
date = {2018-03-01},
journal = {Phys. Rev. A},
volume = {97},
number = {3},
pages = {032704},
abstract = {We have designed, constructed, and commissioned a cryogenic helium buffer-gas source for producing a cryogenically cooled molecular beam and evaluated the effect of different cell geometries on the intensity of the produced molecular beam, using ammonia as a test molecule. Planar and conical entrance and exit geometries are tested. We observe a threefold enhancement in the $textbackslash mathrmNH_3$ signal for a cell with planar entrance and conical-exit geometry, compared to that for a typically used ``boxlike'' geometry with planar entrance and exit. These observations are rationalized by flow field simulations for the different buffer-gas cell geometries. The full thermalization of molecules with the helium buffer gas is confirmed through rotationally resolved resonance-enhanced multiphoton ionization spectra yielding a rotational temperature of 5 K.},
keywords = {Control, experimental design},
pubstate = {published},
tppubtype = {article}
}
We have designed, constructed, and commissioned a cryogenic helium buffer-gas source for producing a cryogenically cooled molecular beam and evaluated the effect of different cell geometries on the intensity of the produced molecular beam, using ammonia as a test molecule. Planar and conical entrance and exit geometries are tested. We observe a threefold enhancement in the $textbackslash mathrmNH_3$ signal for a cell with planar entrance and conical-exit geometry, compared to that for a typically used ``boxlike'' geometry with planar entrance and exit. These observations are rationalized by flow field simulations for the different buffer-gas cell geometries. The full thermalization of molecules with the helium buffer gas is confirmed through rotationally resolved resonance-enhanced multiphoton ionization spectra yielding a rotational temperature of 5 K.
2014
4.
Horke D A, Chang Y, Długołęcki K, Küpper J
Separating Para and Ortho Water Journal Article
In: Angew. Chem. Int. Ed., vol. 53, no. 44, pp. 11965–11968, 2014.
Links | BibTeX | Altmetric | Tags: Control, electrostatic deflector, Simulation
@article{Horke:Angew.Chem.Int.Ed.53:11965,
title = {Separating Para and Ortho Water},
author = {Daniel A Horke and Yuan-Pin Chang and Karol D\lugo\l\k{e}cki and Jochen K\"{u}pper},
url = {http://onlinelibrary.wiley.com/doi/10.1002/anie.201405986/full},
doi = {10.1002/anie.201405986},
year = {2014},
date = {2014-10-01},
journal = {Angew. Chem. Int. Ed.},
volume = {53},
number = {44},
pages = {11965--11968},
keywords = {Control, electrostatic deflector, Simulation},
pubstate = {published},
tppubtype = {article}
}
3.
Horke D A, Chang Y, Długołęcki K, Küpper J
Trennung von Para-und ortho-Wasser Journal Article
In: Angewandte Chemie, vol. 126, no. 44, pp. 12159–12162, 2014.
Links | BibTeX | Altmetric | Tags: Control, electrostatic deflector, Simulation
@article{Horke:AngewandteChemie126:12159,
title = {Trennung von Para-und ortho-Wasser},
author = {Daniel A Horke and Yuan-Pin Chang and Karol D\lugo\l\k{e}cki and Jochen K\"{u}pper},
url = {http://onlinelibrary.wiley.com/doi/10.1002/ange.201405986/full},
doi = {10.1002/ange.201405986},
year = {2014},
date = {2014-10-01},
journal = {Angewandte Chemie},
volume = {126},
number = {44},
pages = {12159--12162},
keywords = {Control, electrostatic deflector, Simulation},
pubstate = {published},
tppubtype = {article}
}
2.
Horke D, Trippel S, Chang Y, Stern S, Mullins T, Kierspel T, pper J K
Spatial Separation of Molecular Conformers and Clusters Journal Article
In: JoVE, no. 83, pp. e51137, 2014, ISSN: 1940-087X.
Abstract | Links | BibTeX | Tags: clusters, Control, electrostatic deflector, Isomer-effects
@article{Horke:JoVE:e51137,
title = {Spatial Separation of Molecular Conformers and Clusters},
author = {Daniel Horke and Sebastian Trippel and Yuan-Pin Chang and Stephan Stern and Terry Mullins and Thomas Kierspel and Jochen K 252 pper},
url = {http://www.jove.com/video/51137},
issn = {1940-087X},
year = {2014},
date = {2014-01-01},
journal = {JoVE},
number = {83},
pages = {e51137},
abstract = {Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold molecular beams. However, these beams often contain multiple conformers and clusters, even at low rotational temperatures. We present an experimental methodology that allows the spatial separation of these constituent parts of a molecular beam expansion. Using an electric deflector the beam is separated by its mass-to-dipole moment ratio, analogous to a bender or an electric sector mass spectrometer spatially dispersing charged molecules on the basis of their mass-to-charge ratio. This deflector exploits the Stark effect in an inhomogeneous electric field and allows the separation of individual species of polar neutral molecules and clusters. It furthermore allows the selection of the coldest part of a molecular beam, as low-energy rotational quantum states generally experience the largest deflection. Different structural isomers (conformers) of a species can be separated due to the different arrangement of functional groups, which leads to distinct dipole moments. These are exploited by the electrostatic deflector for the production of a conformationally pure sample from a molecular beam. Similarly, specific cluster stoichiometries can be selected, as the mass and dipole moment of a given cluster depends on the degree of solvation around the parent molecule. This allows experiments on specific cluster sizes and structures, enabling the systematic study of solvation of neutral molecules.},
keywords = {clusters, Control, electrostatic deflector, Isomer-effects},
pubstate = {published},
tppubtype = {article}
}
Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold molecular beams. However, these beams often contain multiple conformers and clusters, even at low rotational temperatures. We present an experimental methodology that allows the spatial separation of these constituent parts of a molecular beam expansion. Using an electric deflector the beam is separated by its mass-to-dipole moment ratio, analogous to a bender or an electric sector mass spectrometer spatially dispersing charged molecules on the basis of their mass-to-charge ratio. This deflector exploits the Stark effect in an inhomogeneous electric field and allows the separation of individual species of polar neutral molecules and clusters. It furthermore allows the selection of the coldest part of a molecular beam, as low-energy rotational quantum states generally experience the largest deflection. Different structural isomers (conformers) of a species can be separated due to the different arrangement of functional groups, which leads to distinct dipole moments. These are exploited by the electrostatic deflector for the production of a conformationally pure sample from a molecular beam. Similarly, specific cluster stoichiometries can be selected, as the mass and dipole moment of a given cluster depends on the degree of solvation around the parent molecule. This allows experiments on specific cluster sizes and structures, enabling the systematic study of solvation of neutral molecules.
1.
Kierspel T, Horke D A, Chang Y, Küpper J
Spatially Separated Polar Samples of the Cis and Trans Conformers of 3-Fluorophenol Journal Article
In: Chem. Phys. Lett., vol. 591, no. 0, pp. 130–132, 2014.
Links | BibTeX | Altmetric | Tags: Control, electrostatic deflector, Isomer-effects, Simulation
@article{Kierspel:Chem.Phys.Lett.591:130,
title = {Spatially Separated Polar Samples of the Cis and Trans Conformers of 3-Fluorophenol},
author = {Thomas Kierspel and Daniel A Horke and Yuan-Pin Chang and Jochen K\"{u}pper},
url = {http://www.sciencedirect.com/science/article/pii/S0009261413014000},
doi = {10.1016/j.cplett.2013.11.010},
year = {2014},
date = {2014-01-01},
journal = {Chem. Phys. Lett.},
volume = {591},
number = {0},
pages = {130--132},
keywords = {Control, electrostatic deflector, Isomer-effects, Simulation},
pubstate = {published},
tppubtype = {article}
}