Strahlen aus kondensierten Atomen und Molekeln im Hochvakuum

Becker, E. W.; Bier, K.; Henkes, W.

doi:10.1007/bf01330428

Cited by 244 publications

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“…Such clusters were first discovered by Becker et al [1] in 1956 and were investigated systematically by Hagena [2] . Moreover, such clusters have been used for various applications, such as X-ray generation [3] , energetic ion production [4] , and nuclear fusion [5] , after the invention of intense femtosecond laser systems.…”

mentioning

confidence: 99%

Cooling-induced increase of methane cluster size investigated under a Coulomb explosion scheme

Li¹,

Lü²,

Zhang³

et al. 2013

中国光学快报

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In this letter, we discuss the increase in the average cluster size by lowering the stagnation temperature of the methane (CH4) gas. The Coulomb explosion experiments are conducted to estimate the cluster size and the size distribution. The average CH4 cluster sizes Nav of 6 230 and 6 580 are acquired with the source conditions of 30 bars at 240 K and 60 bars at 296 K, respectively. Empirical estimation suggests a five-fold increase in the average size of the CH4 clusters at 240 K compared with that at room temperature under a backing pressure of 30 bars. A strong nonlinear Hagena parameter relation (Γ * ∝ T −3.3 0 ) for the CH4 clusters is revealed. The results may be favorable for the production of large-sized clusters by using gases at low temperature and high back pressures.OCIS codes: 020.2649, 350.5400. doi: 10.3788/COL201311.S20201.Clusters, with van der Waals bonded agglomerations of up to 10 7 atoms, have received considerable attention, and have been investigated because of their density characteristics in internal solid and general gas. Such clusters were first discovered by Becker et al.[1] in 1956 and were investigated systematically by Hagena [2] . Moreover, such clusters have been used for various applications, such as X-ray generation [3] , energetic ion production [4] , and nuclear fusion [5] , after the invention of intense femtosecond laser systems. In 1999, Ditmire et al. demonstrated the deuterium-deuterium (D-D) nuclear fusion in deuterium cluster jets under the irradiation of intense femtosecond laser pulses [5] . Thereafter, intensive studies on laser-cluster interaction have been conducted to generate higher energetic ions and consequently increase fusion neutron yields [6−14] . Theoretical results have revealed the essence of laser-cluster interaction and have proposed the use of heteronuclear clusters, such as deuterated methane (CD 4 ) and heavy water (D 2 O), as targets for generating more energetic light ions compared with homonuclear clusters such as D 2 with the same sizes because of the energetic and kinematic effects [15−18] . The proposal paves the way for future research on the tabletop laser-driven fusion [13,19] , which can provide highflux sources of clean fusion neutrons and short pulse durations. A petawatt-laser-produced [20] fusion neutron source may be of considerable importance to studies on radiation-induced damage on materials, as well as benefit fast neutron radiography, in which the small source size could lead to a high spatial resolution [21] . We have recently demonstrated an efficient fusion neutron generation by using CD 4 clusters under the irradiation of 120-mJ and 60-fs laser pulses [22] . The key factors for generating fusion neutrons includes the energetic deuterons and the density of deuterons inside and around the plasma channel [19,23] . Larger average cluster sizes are required to further increase the average kinetic energy (KE) of exploded deuterons.Gaseous clusters are typically produced through the supersonic expansion of a high backing pressure...

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confidence: 99%

Cooling-induced increase of methane cluster size investigated under a Coulomb explosion scheme

Li¹,

Lü²,

Zhang³

et al. 2013

中国光学快报

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“…To better understand the physical processes in diffusion pumps, Jaeckel had started a research project in his department with the goal of understanding the scattering of simple atoms and molecules from organic (oil) molecules (14). This effort, which started around 1950, was quite independent of the earlier work in Stern's Hamburg laboratory and the contemporary work in Erwin Becker's laboratory in Marburg (15). Hans Pauly (who later became a codirector at the Max-Planck-Institut für Strömungsforschung) was Jaeckel's second student to work on these problems.…”

Section: Postdoc In Bonn: 1957-1965mentioning

confidence: 99%

Serendipitous Meanderings and Adventures With Molecular Beams

Toennies¹

2004

Annu. Rev. Phys. Chem.

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s Abstract This is the story of a native-born American who came as a postdoc to the country of his parents, Germany. There, by good fortune, he could participate in the revival and the rebuilding of the physical sciences following the ravishments of the Second World War, becoming at the age of 38, the director of a Max-Planck-Institut in Göttingen. Working under nearly ideal conditions, he carried out basic research using molecular beams. Aided by many active, youthfully impulsive, yet perceptive and imaginative, students and experienced knowledgeable guest scientists from many countries, he enjoyed exciting adventures into unknown landscapes in the fields of molecular gas-phase interactions and solid-surface phenomena and, most recently, in the realms of quantum liquids and solids.

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“…A gas cluster is an aggregation of several to tens of thousands of atoms or molecules bound by van der Waals forces [24,25]. A beam of gas clusters is typically formed by the adiabatic expansion of a gas at room temperature in a high-vacuum chamber.…”

Section: Introductionmentioning

confidence: 99%

“…A beam of ionized gas clusters is called a gas cluster ion beam (GCIB) [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. In typical GCIB experiments, gas cluster beams are accelerated up to about 20 keV.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Atomic Layer Oxidation of Silicon by Oxygen Gas Cluster Beams

Mizotani

Isobe

Karahashi

et al. 2015

Plasma and Fusion Research

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A gas cluster is a collection of atoms or molecules weakly bound by van der Waals forces. Gas clusters may form by the adiabatic expansion of gases. In this study, it is demonstrated by molecular dynamics simulations that a low-energy beam of oxygen gas clusters may be used to oxidize the top surface layer of silicon (Si) substrates without affecting its deeper layers. An incident oxygen gas cluster with sufficiently low incident energy may stick to the Si surface and expose a large number of oxygen molecules to the surface Si atoms for extended periods until the cluster sublimates. This may cause the formation of Si-O bonds only on the top Si surface. This is in contrast to the oxidation of Si by oxygen ion beams or plasmas, where deeper layers of the Si surface are typically oxidized by the energetic incident oxygen ions. An oxidized single Si layer may be chemically removed; therefore, this nearly single-layer oxidation process by oxygen gas cluster beams may lead to the development of a new atomic layer etching technology for Si.

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Strahlen aus kondensierten Atomen und Molekeln im Hochvakuum

Cited by 244 publications

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Cooling-induced increase of methane cluster size investigated under a Coulomb explosion scheme

Cooling-induced increase of methane cluster size investigated under a Coulomb explosion scheme

Serendipitous Meanderings and Adventures With Molecular Beams

Numerical Simulation of Atomic Layer Oxidation of Silicon by Oxygen Gas Cluster Beams

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