Highly Charged Droplets of Superfluid Helium

Laimer, Felix; Kranabetter, Lorenz; Tiefenthaler, Lukas; Albertini, Simon; Zappa, Fábio; Ellis, Andrew M.; Gatchell, Michael; Scheier, P.

doi:10.1103/physrevlett.123.165301

Cited by 56 publications

(85 citation statements)

References 25 publications

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“…When helium droplets are ionized by electrons with energies above the ionization threshold of He atoms (24.6 eV), positive charges can accumulate within them [43]. If the repulsive forces of the accumulated charges overcome the cohesive forces of the droplets, excess charges will be emitted in the form of small cationic fragments (with a total mass of less than a few percent of that of the parent droplet) [43]. The mass spectrum in the upper panel shows a distribution of such fragments.…”

Section: Resultsmentioning

confidence: 99%

Protonated and Cationic Helium Clusters

et al. 2020

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Protonated rare gas clusters have previously been shown to display markably different structures compared to their pure, cationic counterparts. Here, we have performed high-resolution mass spectrometry measurements of protonated and pristine clusters of He containing up to 50 atoms. We identify notable differences between the magic numbers present in the two types of clusters, but in contrast to heavier rare gas clusters, neither the protonated nor pure clusters exhibit signs of icosahedral symmetries. These findings are discussed in light of results from heavier rare gases and previous theoretical work on protonated helium.

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Section: Resultsmentioning

confidence: 99%

Protonated and Cationic Helium Clusters

et al. 2020

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“…In comparison to experiments with neutral He droplets, the method is more efficient because in the present case, droplets are multiply charged, and therefore, several charged clusters can be formed in each droplet. 20 This way, we are able to reach high signals even at very low pickup pressures, which enables studies of cold biomolecular cluster ions. After pickup and charge transfer from He, the cluster ions inside He droplets are cooled down to a few Kelvin.…”

Section: Methodsmentioning

confidence: 97%

Dissociation of Valine Cluster Cations

et al. 2020

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Independently of the preparation method, for cluster cations of aliphatic amino acids, the protonated form M n H + is always the dominant species. This is a surprising fact considering that in the gas phase, they dissociate primarily by the loss of 45 Da, i.e., the loss of the carboxylic group. In the present study, we explore the dissociation dynamics of small valine cluster cations M n + and their protonated counterparts M n H + via collision-induced dissociation experiments and ab initio calculations with the aim to elucidate the formation of M n H + -type cations from amino acid clusters. For the first time, we report the preparation of valine cluster cations M n + in laboratory conditions, using a technique of cluster ion assembly inside He droplets. We show that the M n + cations cooled down to He droplet temperature can dissociate to form both M n -1 H + and [M n –COOH] + ions. With increasing internal energy, the M n -1 H + formation channel becomes dominant. M n -1 H + ions then fragment nearly exclusively by monomer loss, describing the high abundance of protonated clusters in the mass spectra of amino acid clusters.

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“…Low-energy electrons (red) reduce the net charge of the precursor droplets, increasing their mass-percharge ratio, and high energy electrons (blue) increase the net charge, decreasing the mass-per-charge ratios. Adapted from Laimer et al [172] Quantum vortices carry quantized angular momentum in quantum fluids, e.g. superfluid He, and were first identified in large (> 300 nm diameter) helium droplets doped with Ag atoms where the vortices facilitated the growth of nanowires [169].…”

Section: Status: Description Of the State Of The Artmentioning

confidence: 99%

Roadmap on dynamics of molecules and clusters in the gas phase

et al. 2021

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This roadmap article highlights recent advances, challenges and future prospects in studies of the dynamics of molecules and clusters in the gas phase. It comprises nineteen contributions by scientists with leading expertise in complementary experimental and theoretical techniques to probe the dynamics on timescales spanning twenty order of magnitudes, from attoseconds to minutes and beyond, and for systems ranging in complexity from the smallest (diatomic) molecules to clusters and nanoparticles. Combining some of these techniques opens up new avenues to unravel hitherto unexplored reaction pathways and mechanisms, and to establish their significance in, e.g. radiotherapy and radiation damage on the nanoscale, astrophysics, astrochemistry and atmospheric science. Graphic abstract

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Highly Charged Droplets of Superfluid Helium

Cited by 56 publications

References 25 publications

Protonated and Cationic Helium Clusters

Protonated and Cationic Helium Clusters

Dissociation of Valine Cluster Cations

Roadmap on dynamics of molecules and clusters in the gas phase

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