Fullerenes are graphitic cage structures incorporating exactly twelve pentagons. The smallest possible fullerene is thus C20, which consists solely of pentagons. But the extreme curvature and reactivity of this structure have led to doubts about its existence and stability. Although theoretical calculations have identified, besides this cage, a bowl and a monocyclic ring isomer as low-energy members of the C20 cluster family, only ring isomers of C20 have been observed so far. Here we show that the cage-structured fullerene C20 can be produced from its perhydrogenated form (dodecahedrane C20H20) by replacing the hydrogen atoms with relatively weakly bound bromine atoms, followed by gas-phase debromination. For comparison we have also produced the bowl isomer of C20 using the same procedure. We characterize the generated C20 clusters using mass-selective anion photoelectron spectroscopy; the observed electron affinities and vibrational structures of these two C20 isomers differ significantly from each other, as well as from those of the known monocyclic isomer. We expect that these unique C20 species will serve as a benchmark test for further theoretical studies.

Gas-phase production and photoelectron spectroscopy of the smallest fullerene, C20

Volume 1: atomic structure stability and evolution dynamics electronic structure magnetism. Volume 2: electrical and optical properties cluster reactions and cluster-support interactions cluster assemblies materials involving carbon.

/pdf/physics-and-chemistry-of-finite-systems-from-clusters-to-3nrgsksx1f.pdf

Physics and Chemistry of Finite Systems: From Clusters to Crystals

Interatomic or intermolecular Coulombic decay (ICD) is a nonlocal electronic decay mechanism occurring in weakly bound matter. In an ICD process, energy released by electronic relaxation of an excited atom or molecule leads to ionization of a neighboring one via Coulombic electron interactions. ICD has been predicted theoretically in the mid nineties of the last century, and its existence has been confirmed experimentally approximately ten years later. Since then, a number of fundamental and applied aspects have been studied in this quickly growing field of research. This review provides an introduction to ICD and draws the connection to related energy transfer and ionization processes. The theoretical approaches for the description of ICD as well as the experimental techniques developed and employed for its investigation are described. The existing body of literature on experimental and theoretical studies of ICD processes in different atomic and molecular systems is reviewed.

Interatomic and Intermolecular Coulombic Decay.

We describe a new reflectron time‐of‐flight mass spectrometer configuration for laser photodissociation of mass‐selected ions and the initial performance characteristics observed for this instrument. Ions are produced by laser photoionization within the acceleration region of the instrument or by laser vaporization in an external pulsed‐nozzle cluster ion source. Mass selection is accomplished with pulsed deflection plates at the end of an initial drift section. Laser photodissociation of selected ions takes place at the turning point in the ion trajectory in the reflectron. The transit time through a second drift section defines the fragment ion masses. Optimized operating conditions and the role of mass discrimination in this instrument are discussed.

Reflectron time‐of‐flight mass spectrometer for laser photodissociation

A tandem mass spectrometer includes a linear time-of-flight mass analyzer and a curved­field reflectron mass analyzer. The curved-field reflectron mass analyzer is disposed at an end of the linear time-of-flight mass analyzer such that ions having a plurality of ion masses formed in the linear time-of-flight analyzer enter the curved-field reflectron mass analyzer. The tandem mass spectrometer also includes a mass selection gate disposed between the time-of-flight mass analyzer and the curved-field reflectron mass analyzer. The mass selection gate selects an ion mass from the plurality of ion masses. Furthermore, the tandem mass spectrometer also includes a dissociating component located in a path of the ions formed in the linear time-of-flight analyzer. The dissociating component causes dissociation of the ions into a plurality of ion fragments.

Tandem time-of-flight mass spectrometer

Photoabsorption cross sections for ${\mathrm{Ar}}_{\mathit{n}}^{+}$, 3\ensuremath{\le}n\ensuremath{\le}80, and ${\mathrm{Xe}}_{\mathit{n}}^{+}$, 3\ensuremath{\le}n\ensuremath{\le}30 clusters have been measured. A single absorption maximum in the visible is observed for ${\mathrm{Ar}}_{\mathit{n}}^{+}$, whose redshift with growing n is interpreted as a delocalization of the charge from a trimer to a tetramer ion. For ${\mathrm{Xe}}_{3}^{+}$, two maxima, and for ${\mathrm{Xe}}_{\mathit{n}}^{+}$, n\ensuremath{\ge}5, three maxima are observed. For n\ensuremath{\ge}5 the positive charge can localize onto either a trimer or a tetramer ion core, both surrounded by neutral atoms. The transition between the two isomers is faster than 10 ns.

Electronic and geometric structure of Ar n + and Xe n + clusters: The solvation of rare-gas ions by their parent atoms

Adding a simple mass gate at the first time focus of a reflectron‐type time‐of‐flight mass spectrometer, one mass can be selected and its further decay or interaction studied. A new type of mass gate is described that does not have any grids. It is especially suitable for cluster studies. Three processes are identified that lead to an undesirable high background in a reflectron time‐of‐flight mass spectrometer.

Converting a reflectron time‐of‐flight mass spectrometer into a tandem instrument

An apparatus is described for the measurement of photo processes in mass‐selected cluster ions. A gridless reflectron type of time‐of‐flight (TOF) mass spectrometer is used to select an ion of known mass. The selected ion is photoexcited with a pulsed dye laser. The charged fragments are mass separated in a second linear TOF. A new combination of reflectron and linear TOF is described, which allows one to measure the complete photofragment mass distribution over an arbitrary large mass range for each laser shot, which was not possible earlier. It is discussed how clusters with different temperatures can be prepared. The first measurement of a temperature‐dependent effect for mass‐selected free cluster ions is presented.

A double/triple time‐of‐flight mass spectrometer for the study of photoprocesses in clusters, or how to produce cluster ions with different temperatures

A tandem time-of-flight mass spectrometer is used to measure photofragmentation mass spectra and optical absorption spectra of mass selected argon cluster ions in then=3 to 108 atoms per cluster range.

Photofragmentation and photoabsorption cross sections for mass selected argon cluster ions,n=3 to 108

Neutral rare gas clusters have one of the simplest kind of chemical binding. Every atom is bound to its neighbours by the same kind of weak undirectional van der Waals force. The first electronic excitation is far in the vacuum UV region [1]. An electron is removed from a strongly antibonding orbital if the duster is ionised. Consequently the bonding becomes much stronger around the charge, and differs in character, direction and strength. The optical absorption shifts to the visible. The absorption is due to the charge localisation on a molecular chromophore. It was originally deduced from energetic considerations and condensed state data [2], that the positive charge in a rare gas cluster ion localizes after about a picosecond on a dimer ion, e.g. Ar 2 + . An argon cluster ion Ar n + would thus have a Ar 2 + Ar n−2. structure. Later experimental [3, 4, 5, 6, 7] and theoretical [8, 9, 10] results pointed to charge localization on a larger unit: Ar n + with n = 3 or 4. This view is not universally shared: Stace and coworkers [11] deduce from their data that the charge does localize on a dimer ion. However Deluca and Johnson [12] and Bowers et al.[13] favour an Ar 2 + − Ar double minimum potential, a notion which is contested by Gadea and Malrieu [14]. Carnovale et al. [15] deduce from their photoelectron spectra n = 3, 7, or 13, depending on cluster size.

Optical Spectroscopy of Argon Cluster Ions

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Andreas Risch

Author Tools

Chat about Author