Spectroscopy of light-molecule endofullerenes

Molecular endofullerenes are supramolecular systems consisting of fullerene cages encapsulating small molecules. Although most early examples consist of encapsulated metal clusters, recently developed synthetic routes have provided endofullerenes with non-metallic guest molecules in high purity and macroscopic quantities. The encapsulated light molecule behaves as a confined quantum rotor, displaying rotational quantization as well as translational quantization, and a rich coupling between the translational and rotational degrees of freedom. Furthermore, many encapsulated molecules display spin isomerism. Spectroscopies such as inelastic neutron scattering, nuclear magnetic resonance and infrared spectroscopy may be used to obtain information on the quantized energy level structure and spin isomerism of the guest molecules. It is also possible to study the influence of the guest molecules on the cages, and to explore the communication between the guest molecules and the molecular environment outside the cage.

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Coupling between electronic and lattice degrees of freedom in 4f-electron systems investigated by inelastic neutron scattering

Journal of Physics Condensed Matter ◽

10.1088/0953-8984/15/5/307 ◽

2003 ◽

Vol 15 (5) ◽

pp. S519-S536 ◽

Cited By ~ 13

Author(s):

M Loewenhaupt ◽

U Witte

Keyword(s):

Neutron Scattering ◽

Degrees Of Freedom ◽

Inelastic Neutron Scattering ◽

Inelastic Neutron ◽

Electron Systems

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Drug Guest Molecules as Modulators During One-Step Mechanochemical Encapsulation in MIL-100 (Fe) Framework

10.26434/chemrxiv.12782165 ◽

2020 ◽

Author(s):

Barbara Souza ◽

Annika Moslein ◽

Kirill Titov ◽

James D. Taylor ◽

Svemir Rudic ◽

...

Keyword(s):

Neutron Scattering ◽

Intermolecular Interactions ◽

Inelastic Neutron Scattering ◽

Inelastic Neutron ◽

One Pot ◽

Guest Molecules ◽

Host Interaction ◽

One Step

<p>We propose a facile one-pot mechanochemical strategy for the encapsulation of drug guest molecules (e.g. 5‑fluorouracil, caffeine, and aspirin) in MIL-100 (Fe) as the porous host framework. We reveal the modulating effect of 5-FU and caffeine, giving highly crystalline MIL‑100 (Fe), whereas aspirin led to the formation of an amorphous MOF phase. Inelastic neutron scattering (INS) was used to probe the intermolecular interactions underpinning the drug@MIL‑100 assemblies, where strong guest-host interaction was achieved <i>via</i> this eco-friendly approach.</p>

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Spectroscopic characterization of actinide materials

MRS Bulletin ◽

10.1557/mrs2010.716 ◽

2010 ◽

Vol 35 (11) ◽

pp. 889-895 ◽

Cited By ~ 4

Author(s):

R. Caciuffo ◽

E. C. Buck ◽

D. L. Clark ◽

G. van der Laan

Keyword(s):

Electronic Structure ◽

Degrees Of Freedom ◽

Inelastic Neutron Scattering ◽

Occupation Number ◽

Spectroscopic Characterization ◽

Inelastic Neutron ◽

Spectroscopic Techniques ◽

Magnetic Fluctuations ◽

Electronic Density ◽

X Ray

Advanced spectroscopic techniques provide new and unique tools for unraveling the nature of the electronic structure of actinide materials. Inelastic neutron scattering experiments, which address temporal aspects of lattice and magnetic fluctuations, probe electromagnetic multipole interactions and the coupling between electronic and vibrational degrees of freedom. Nuclear magnetic resonance clearly demonstrates different magnetic ground states at low temperature. Photoemission spectroscopy provides information on the occupied part of the electronic density of states and has been used to investigate the momentum-resolved electronic structure and the topology of the Fermi surface in a variety of actinide compounds. Furthermore, x-ray absorption and electron energy-loss spectroscopy have been used to probe the relativistic nature, occupation number, and degree of localization of 5f electrons across the actinide series. More recently, element- and edge-specific resonant and non-resonant inelastic x-ray scattering experiments have provided the opportunity of measuring elementary electronic excitations with higher resolution than traditional absorption techniques. Here, we will discuss results from these spectroscopic techniques and what they tell us of the electronic and magnetic properties of selected actinide materials.

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Simple and Binary Hydrogen Clathrate Hydrates: Synthesis and Microscopic Characterization through Neutron and Raman Scattering

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.72.196 ◽

2010 ◽

Vol 72 ◽

pp. 196-204 ◽

Cited By ~ 3

Author(s):

Milva Celli ◽

Daniele Colognesi ◽

Alessandra Giannasi ◽

Lorenzo Ulivi ◽

Marco Zoppi ◽

...

Keyword(s):

Inelastic Neutron Scattering ◽

Inelastic Neutron ◽

Clathrate Hydrates ◽

Hydrogen Release ◽

Appreciable Amount ◽

Crystal Stability ◽

Production Of Hydrogen ◽

Spectroscopic Information ◽

Speed Up ◽

Synthetic Routes

The search for efficient hydrogen-storage materials has led to an increasing interest in hydrogen clathrate hydrates, since it has been demonstrated that an appreciable amount of molecular hydrogen can be stored in the water cages and released at melting. Different synthetic routes have been followed to maximize the quantity of trapped hydrogen and to speed up the kinetics of the clathrate formation. Here, we describe two different synthetic routes for the production of hydrogen clathrate hydrates. Then we present the results of inelastic neutron scattering and Raman light scattering experiments on simple (i.e. containing only hydrogen) and binary (i.e. with a second guest molecule) clathrates. For each class of compounds, we have obtained spectroscopic information on the motion of hydrogen inside the cages, on the occupancy of the cages by hydrogens, and on lattice dynamics. Finally, we have investigated the clathrate crystal stability and the hydrogen release as a function of temperature by means of neutron diffraction.

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Drug Guest Molecules as Modulators During One-Step Mechanochemical Encapsulation in MIL-100 (Fe) Framework

10.26434/chemrxiv.12782165.v1 ◽

2020 ◽

Author(s):

Barbara Souza ◽

Annika Moslein ◽

Kirill Titov ◽

James D. Taylor ◽

Svemir Rudic ◽

...

Keyword(s):

Neutron Scattering ◽

Intermolecular Interactions ◽

Inelastic Neutron Scattering ◽

Inelastic Neutron ◽

One Pot ◽

Guest Molecules ◽

Host Interaction ◽

One Step

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Pristine quantum criticality in a Kondo semimetal

Science Advances ◽

10.1126/sciadv.abf9134 ◽

2021 ◽

Vol 7 (21) ◽

pp. eabf9134

Author(s):

Wesley T. Fuhrman ◽

Andrey Sidorenko ◽

Jonathan Hänel ◽

Hannes Winkler ◽

Andrey Prokofiev ◽

...

Keyword(s):

Degrees Of Freedom ◽

Inelastic Neutron Scattering ◽

Inelastic Neutron ◽

Quantum Criticality ◽

Energy Scale ◽

Strongly Correlated ◽

Strongly Correlated Electron ◽

Correlated Electron Systems ◽

Correlated Electron ◽

Temperature Scaling

The observation of quantum criticality in diverse classes of strongly correlated electron systems has been instrumental in establishing ordering principles, discovering new phases, and identifying the relevant degrees of freedom and interactions. At focus so far have been insulators and metals. Semimetals, which are of great current interest as candidate phases with nontrivial topology, are much less explored in experiments. Here, we study the Kondo semimetal CeRu4Sn6 by magnetic susceptibility, specific heat, and inelastic neutron scattering experiments. The power-law divergence of the magnetic Grünesien ratio reveals that, unexpectedly, this compound is quantum critical without tuning. The dynamical energy over temperature scaling in the neutron response throughout the Brillouin zone and the temperature dependence of the static uniform susceptibility, indicate that temperature is the only energy scale in the criticality. Such behavior, which has been associated with Kondo destruction quantum criticality in metallic systems, could be generic in the semimetal setting.

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Aspirin locally disrupts the liquid-ordered phase

Royal Society Open Science ◽

10.1098/rsos.171710 ◽

2018 ◽

Vol 5 (2) ◽

pp. 171710 ◽

Cited By ~ 1

Author(s):

Richard J. Alsop ◽

Sebastian Himbert ◽

Alexander Dhaliwal ◽

Karin Schmalzl ◽

Maikel C. Rheinstädter

Keyword(s):

Small Molecules ◽

Local Structure ◽

Lipid Membranes ◽

Inelastic Neutron Scattering ◽

Md Simulations ◽

Inelastic Neutron ◽

Membrane Function ◽

Structure And Dynamics ◽

Liquid Ordered ◽

Functional Interface

Local structure and dynamics of lipid membranes play an important role in membrane function. The diffusion of small molecules, the curvature of lipids around a protein and the existence of cholesterol-rich lipid domains (rafts) are examples for the membrane to serve as a functional interface. The collective fluctuations of lipid tails, in particular, are relevant for diffusion of membrane constituents and small molecules in and across membranes, and for structure and formation of membrane domains. We studied the effect of aspirin (acetylsalicylic acid, ASA) on local structure and dynamics of membranes composed of dimyristoylphosphocholine (DMPC) and cholesterol. Aspirin is a common analgesic, but is also used in the treatment of cholesterol. Using coherent inelastic neutron scattering experiments and molecular dynamics (MD) simulations, we present evidence that ASA binds to liquid-ordered, raft-like domains and disturbs domain organization and dampens collective fluctuations. By hydrogen-bonding to lipid molecules, ASA forms ‘superfluid’ complexes with lipid molecules that can organize laterally in superlattices and suppress cholesterol’s ordering effect.

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Fractional and composite excitations of antiferromagnetic quantum spin trimer chains

npj Quantum Materials ◽

10.1038/s41535-021-00416-4 ◽

2022 ◽

Vol 7 (1) ◽

Author(s):

Jun-Qing Cheng ◽

Jun Li ◽

Zijian Xiong ◽

Han-Qing Wu ◽

Anders W. Sandvik ◽

...

Keyword(s):

Quantum Monte Carlo ◽

Degrees Of Freedom ◽

Inelastic Neutron Scattering ◽

High Energy ◽

Inelastic Neutron ◽

Intermediate Energy ◽

Quantum Spin ◽

One Dimensional ◽

Quantum Magnet ◽

Coupling Strengths

AbstractUsing quantum Monte Carlo, exact diagonalization, and perturbation theory, we study the spectrum of the S = 1/2 antiferromagnetic Heisenberg trimer chain by varying the ratio g = J2/J1 of the intertrimer and intratrimer coupling strengths. The doublet ground states of trimers form effective interacting S = 1/2 degrees of freedom described by a Heisenberg chain. Therefore, the conventional two-spinon continuum of width ∝ J1 when g = 1 evolves into to a similar continuum of width ∝ J2 when g → 0. The intermediate-energy and high-energy modes are termed doublons and quartons which fractionalize with increasing g to form the conventional spinon continuum. In particular, at g ≈ 0.716, the gap between the low-energy spinon branch and the high-energy band with mixed doublons, quartons, and spinons closes. These features should be observable in inelastic neutron scattering experiments if a quasi-one-dimensional quantum magnet with the linear trimer structure and J2 < J1 can be identified. Our results may open a window for exploring the high-energy fractional excitations.

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Cation Dynamics in Hybrid Halide Perovskites

Annual Review of Materials Research ◽

10.1146/annurev-matsci-080819-012808 ◽

2021 ◽

Vol 51 (1) ◽

Author(s):

Eve M. Mozur ◽

James R. Neilson

Keyword(s):

Neutron Scattering ◽

Degrees Of Freedom ◽

Materials Science ◽

Inelastic Neutron Scattering ◽

Inelastic Neutron ◽

Annual Review ◽

Publication Date ◽

Elastic Neutron ◽

Halide Perovskites ◽

Spectroscopy Studies

Hybrid halide perovskite semiconductors exhibit complex, dynamical disorder while also harboring properties ideal for optoelectronic applications that include photovoltaics. However, these materials are structurally and compositionally distinct from traditional compound semiconductors composed of tetrahedrally coordinated elements with an average valence electron count of silicon. The additional dynamic degrees of freedom of hybrid halide perovskites underlie many of their potentially transformative physical properties. Neutron scattering and spectroscopy studies of the atomic dynamics of these materials have yielded significant insights into their functional properties. Specifically, inelastic neutron scattering has been used to elucidate the phonon band structure, and quasi-elastic neutron scattering has revealed the nature of the uncorrelated dynamics pertaining to molecular reorientations. Understanding the dynamics of these complex semiconductors has elucidated the temperature-dependent phase stability and origins of defect-tolerant electronic transport from the highly polarizable dielectric response. Furthermore, the dynamic degrees of freedom of the hybrid perovskites provide additional opportunities for application engineering and innovation. Expected final online publication date for the Annual Review of Materials Science, Volume 51 is August 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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