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Bradford SD, Ge Y, Zhang J, Trejo M, Tronrud D, Kong W. Electron diffraction of 1,4-dichlorobenzene embedded in superfluid helium droplets. Phys Chem Chem Phys 2022; 24:27722-27730. [PMID: 36377553 PMCID: PMC9731815 DOI: 10.1039/d2cp04492g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
We perform electron diffraction of 1,4-dichlorobenzene (C6H4Cl2, referred to as 2ClB) embedded in superfluid helium droplets to investigate the structure evolution of cluster growth. Multivariable linear regression fittings are used to determine the concentration and the best model structures of the clusters. At a droplet source temperature of 22 K with droplets containing on average 5000 He atoms, the fitting results agree with the doping statistics modeled using the Poisson distribution: the largest molecular clusters are tetramers, while the abundances of monomers and dimers are the highest and are similar. Molecular dimers of 2ClB are determined to have a parallel structure with a 60° rotation for the Cl-Cl molecular axes. However, a better agreement between experiment and fitting is obtained by reducing the interlayer distance that had been calculated using the density functional theory for dimers. Further calculations using the highest level quantum mechanical calculations prove that the reduction in interlayer distance does not significantly increase the energy of the dimer. Cluster trimers adopt a dimer structure with the additional monomer slanted against the dimer, and tetramers take on a stacked structure. The structure evolution with cluster size is extraordinary, because from trimer to tetramer, one monomer needs to be rearranged, and neither the trimer nor the tetramer adopts the corresponding global minimum structure obtained using high level coupled-cluster theory calculations. This phenomenon may be related to the fast cooling process in superfluid helium droplets during cluster formation.
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Affiliation(s)
- Stephen D Bradford
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
| | - Yingbin Ge
- Department of Chemistry, Central Washington University, Ellensburg, WA 98926, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
| | - Marisol Trejo
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
| | - Dale Tronrud
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
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Zhang J, Kong W. Electron diffraction as a structure tool for charged and neutral nanoclusters formed in superfluid helium droplets. Phys Chem Chem Phys 2022; 24:6349-6362. [PMID: 35257134 PMCID: PMC10508180 DOI: 10.1039/d2cp00048b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This perspective presents the current status and future directions in using electron diffraction to determine the structures of clusters formed in superfluid helium droplets. The details of the experimental setup and data treatment procedures are explained, and several examples are illustrated. The ease of forming atomic and molecular clusters has been recognized since the invention of superfluid helium droplet beams. To resolve atomic structures from clusters formed in droplets, substantial efforts have been devoted to minimizing the contribution of helium to diffraction signals. With active background subtraction, we have obtained structures from clusters containing a few to more than 10 monomers, with and without heavy atoms to assist with the diffraction intensity, for both neutral and ionic species. From fittings of the diffraction profiles using model structures, we have observed that some small clusters adopt the structures of the corresponding solid sample, even for dimers such as iodine and pyrene, while others require trimers or tetramers to reach the structural motif of bulk solids, and smaller clusters such as CS2 dimers adopt gas phase structures. Cationic clusters of argon clusters contain an Ar3+ core, while pyrene dimers demonstrate a change in the intermolecular distance, from 3.5 Å for neutral dimers to 3.0 Å for cations. Future improvements in reducing the background of helium, and in expanding the information content of electron diffraction such as detection of charge distributions, are also discussed.
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Affiliation(s)
- Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
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Lei L, Zhang J, Trejo M, Bradford SD, Kong W. Resolving the interlayer distance of cationic pyrene clusters embedded in superfluid helium droplets using electron diffraction. J Chem Phys 2022; 156:051101. [DOI: 10.1063/5.0080365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Lei Lei
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Marisol Trejo
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Stephen D. Bradford
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
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Zhang J, Trejo M, Bradford SD, Lei L, Kong W. Electron Diffraction of Ionic Argon Nanoclusters Embedded in Superfluid Helium Droplets. J Phys Chem Lett 2021; 12:9644-9650. [PMID: 34586826 PMCID: PMC8550877 DOI: 10.1021/acs.jpclett.1c02712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report electron diffraction of cationic argon nanoclusters embedded in superfluid helium droplets. Superfluid helium droplets are first doped with neutral argon atoms to form nanoclusters, and then the doped droplets are ionized by electrons. The much lower ionization energy of argon ensures that the positive charge resides on the Ar nanocluster. Using different stagnation temperatures and therefore droplets with different sizes, we have been able to preferentially form a small ionic cluster containing 2-4 Ar atoms and a larger cluster containing 7-11 atoms. The fitting results of the diffraction profiles agree with structures reported from theoretical calculations, containing a cationic trimer core with the remaining atoms largely neutral. This work testifies to the feasibility of performing electron diffraction from ionic species embedded in superfluid helium droplets, dispelling the concern over the particle density in the diffraction region. However, the large number of neutral helium atoms surrounding the cationic nanoclusters poses a challenge for the detection of the helium solvation layer, and the detection of which awaits further technological improvements.
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Affiliation(s)
| | | | | | | | - Wei Kong
- Corresponding author, , 541-737-6714
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Zhang J, Bradford SD, Kong W, Zhang C, Xue L. Electron diffraction of CS 2 nanoclusters embedded in superfluid helium droplets. J Chem Phys 2020; 152:224306. [PMID: 32534524 PMCID: PMC7292678 DOI: 10.1063/5.0011340] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 05/25/2020] [Indexed: 11/14/2022] Open
Abstract
We report experimental results from electron diffraction of CS2 nanoclusters embedded in superfluid helium droplets. From detailed measurements of the sizes of doped droplets, we can model the doping statistics under different experimental conditions, thereby obtaining the range of cluster sizes of CS2. Using a least squares fitting procedure, we can then determine the structures and contributions of dimers, trimers, and tetramers embedded in small droplets. While dimers prefer a stable gas phase structure, trimers and tetramers seem to forgo the highly symmetric gas phase structures and prefer compact cuts from the crystalline structure of CS2. In larger droplets containing more than 12 CS2 monomers, the diffraction profile is consistent with a three-dimensional nanostructure of bulk CS2. This work demonstrates the feasibility of electron diffraction for in situ monitoring of nanocluster formation in superfluid helium droplets.
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Affiliation(s)
- Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Stephen D. Bradford
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Chengzhu Zhang
- Department of Statistics, Oregon State University, Corvallis, Oregon 97331, USA
| | - Lan Xue
- Department of Statistics, Oregon State University, Corvallis, Oregon 97331, USA
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Lei L, Yao Y, Zhang J, Tronrud D, Kong W, Zhang C, Xue L, Dontot L, Rapacioli M. Electron Diffraction of Pyrene Nanoclusters Embedded in Superfluid Helium Droplets. J Phys Chem Lett 2020; 11:724-729. [PMID: 31884792 PMCID: PMC7104692 DOI: 10.1021/acs.jpclett.9b03603] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report electron diffraction of pyrene nanoclusters embedded in superfluid helium droplets. Using a least-squares fitting procedure, we have been able to separate the contribution of helium from those of the pyrene nanoclusters and determine the most likely structures for dimers and trimers. We confirm that pyrene dimers form a parallel double-layer structure with an interlayer distance of 3.5 Å and suggest that pyrene trimers form a sandwich structure but that the molecular planes are not completely parallel. The relative contributions of the dimers and trimers are ∼6:1. This work is an extension of our effort of solving structures of biological molecules using serial single-molecule electron diffraction imaging. The success of electron diffraction from an all-light-atom sample embedded in helium droplets offers reassuring evidence of the feasibility of this approach.
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Affiliation(s)
- Lei Lei
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Yuzhong Yao
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Dale Tronrud
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Chengzhu Zhang
- Department of Statistics, Oregon State University, Corvallis, Oregon 97331, United States
| | - Lan Xue
- Department of Statistics, Oregon State University, Corvallis, Oregon 97331, United States
| | - Léo Dontot
- Laboratoire de Chimie et Physique Quantiques, LCPQ/IRSAMC, UMR5626, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Mathias Rapacioli
- Laboratoire de Chimie et Physique Quantiques, LCPQ/IRSAMC, UMR5626, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
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Niman JW, Kamerin BS, Merthe DJ, Kranabetter L, Kresin VV. Oriented Polar Molecules Trapped in Cold Helium Nanodropets: Electrostatic Deflection, Size Separation, and Charge Migration. PHYSICAL REVIEW LETTERS 2019; 123:043203. [PMID: 31491260 DOI: 10.1103/physrevlett.123.043203] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Indexed: 06/10/2023]
Abstract
Helium nanodroplets doped with polar molecules are studied by electrostatic deflection. This broadly applicable method allows even polyatomic molecules to attain subkelvin temperatures and nearly full orientation in the field. The resulting intense force from the field gradient strongly deflects even droplets with tens of thousands of atoms, the most massive neutral systems studied by beam "deflectometry." We use the deflections to extract droplet size distributions. Moreover, since each host droplet deflects according to its mass, spatial filtering of the deflected beam translates into size filtering of neutral fragile nanodroplets. As an example, we measure the dopant ionization probability as a function of droplet radius and determine the mean free path for charge hopping through the helium matrix. The technique will enable separation of doped and neat nanodroplets and size-dependent spectroscopic studies.
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Affiliation(s)
- John W Niman
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0484, USA
| | - Benjamin S Kamerin
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0484, USA
| | - Daniel J Merthe
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0484, USA
| | - Lorenz Kranabetter
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Vitaly V Kresin
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0484, USA
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Alghamdi M, Zhang J, Oswalt A, Porter JJ, Mehl RA, Kong W. Doping of Green Fluorescent Protein into Superfluid Helium Droplets: Size and Velocity of Doped Droplets. J Phys Chem A 2017; 121:6671-6678. [PMID: 28825305 PMCID: PMC5713884 DOI: 10.1021/acs.jpca.7b05718] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We report doping of green fluorescent protein from an electrospray ionization (ESI) source into superfluid helium droplets. From analyses of the time profiles of the doped droplets, we identify two distinct groups of droplets. The faster group has a smaller average size, on the order of 106 helium atoms/droplet, and the slower group is much larger, by at least an order of magnitude. The relative populations of these two groups depend on the temperature of the droplet source: from 11 to 5 K, the signal intensity of the slower droplet group gradually increases, from near the detection limit to comparable to that of the faster group. We postulate that the smaller droplets are formed via condensation of gaseous helium upon expansion from the pulsed valve, while the larger droplets develop from fragmentation of ejected liquid helium. Our results on the size and velocity of the condensation peak at higher source temperatures (>7 K) agree with previous reports, but those at lower temperatures (<7 K) seem to be off. We attribute this discrepancy to the masking effect of the exceedingly large droplets from the fragmentation peak in previous measurements of droplet sizes. Within the temperature range of our investigation, although the expansion condition changes from subcritical to supercritical, there is no abrupt change in either the velocity distribution or the size distribution of the condensation peak, and the most salient effect is in the increasing intensity of the fragmentation peak. The absolute doping efficiency, as expressed by the ratio of ion-doped droplets over the total number of ions from the ESI source, is on the order of 10-4, while only hundreds of doped ions have been detected. Further improvements in the ESI source are key to extending the technology for future experiments. On the other hand, the separation of the two groups of droplets in velocity is beneficial for size selection of only the smaller droplets for future experiments of electron diffraction.
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Affiliation(s)
- Maha Alghamdi
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Andrew Oswalt
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Joseph J. Porter
- Department of Biochemistry and Biophysics, Oregon State University, 2011 Agricultural and Life Science building, Corvallis, Oregon 97331, USA
| | - Ryan A. Mehl
- Department of Biochemistry and Biophysics, Oregon State University, 2011 Agricultural and Life Science building, Corvallis, Oregon 97331, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
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Chatterley AS, Shepperson B, Stapelfeldt H. Three-Dimensional Molecular Alignment Inside Helium Nanodroplets. PHYSICAL REVIEW LETTERS 2017; 119:073202. [PMID: 28949671 DOI: 10.1103/physrevlett.119.073202] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Indexed: 05/23/2023]
Abstract
We demonstrate 3D spatial alignment of 3,5-dichloroiodobenzene molecules embedded in helium nanodroplets using nonresonant elliptically polarized 160 ps laser pulses at a 1 kHz repetition rate. Through Coulomb explosion imaging and ion-ion covariance mapping, the 3D alignment is characterized and found to be stronger than that of isolated molecules. The 3D alignment follows the intensity profile of the alignment laser pulse almost adiabatically, except for a delayed response in the helium droplets, which could be exploited for field-free 3D alignment. Our results pave the way for next-generation molecular dynamics and diffraction experiments, performed within a cold helium solvent.
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Affiliation(s)
- Adam S Chatterley
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Benjamin Shepperson
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Henrik Stapelfeldt
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
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He Y, Zhang J, Lei L, Kong W. Self-Assembly of Iodine in Superfluid Helium Droplets: Halogen Bonds and Nanocrystals. Angew Chem Int Ed Engl 2017; 56:3541-3545. [PMID: 28220998 DOI: 10.1002/anie.201611922] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 01/18/2017] [Indexed: 11/09/2022]
Abstract
We present evidence of halogen bond in iodine clusters formed in superfluid helium droplets based on results from electron diffraction. Iodine crystals are known to form layered structures with intralayer halogen bonds, with interatomic distances shorter than the sum of the van der Waals radii of the two neighboring atoms. The diffraction profile of dimer dominated clusters embedded in helium droplets reveals an interatomic distance of 3.65 Å, much closer to the value of 3.5 Å in iodine crystals than to the van der Waals distance of 4.3 Å. The profile from larger iodine clusters deviates from a single layer structure; instead, a bi-layer structure qualitatively fits the experimental data. This work highlights the possibility of small halogen bonded iodine clusters, albeit in a perhaps limited environment of superfluid helium droplets. The role of superfluid helium in guiding the trapped molecules into local potential minima awaits further investigation.
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Affiliation(s)
- Yunteng He
- Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA
| | - Lei Lei
- Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA
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He Y, Zhang J, Lei L, Kong W. Self‐Assembly of Iodine in Superfluid Helium Droplets: Halogen Bonds and Nanocrystals. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yunteng He
- Department of Chemistry Oregon State University Corvallis OR 97331 USA
| | - Jie Zhang
- Department of Chemistry Oregon State University Corvallis OR 97331 USA
| | - Lei Lei
- Department of Chemistry Oregon State University Corvallis OR 97331 USA
| | - Wei Kong
- Department of Chemistry Oregon State University Corvallis OR 97331 USA
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Zhang J, He Y, Kong W. Communication: Electron diffraction of ferrocene in superfluid helium droplets. J Chem Phys 2016; 144:221101. [PMID: 27305988 DOI: 10.1063/1.4953250] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report electron diffraction of ferrocene doped in superfluid helium droplets. By taking advantage of the velocity slip in our pulsed droplet beam using a pulsed electron gun, and by doping with a high concentration of ferrocene delivered via a pulsed valve, we can obtain high quality diffraction images from singly doped droplets. Under the optimal doping conditions, 80% of the droplets sampled in the electron beam are doped with just one ferrocene molecule. Extension of this size selection method to dopant clusters has also been demonstrated. However, incomplete separation of dopant clusters might require deconvolution and modeling of the doping process. This method can be used for studies of nucleation processes in superfluid helium droplets.
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Affiliation(s)
- Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Yunteng He
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
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