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Kranabetter L, Bersenkowitsch NK, Martini P, Gatchell M, Kuhn M, Laimer F, Schiller A, Beyer MK, Ončák M, Scheier P. Considerable matrix shift in the electronic transitions of helium-solvated cesium dimer cation Cs 2He. Phys Chem Chem Phys 2019; 21:25362-25368. [PMID: 31702748 PMCID: PMC7116336 DOI: 10.1039/c9cp04790e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
We investigate the photodissociation of helium-solvated cesium dimer cations using action spectroscopy and quantum chemical calculations. The spectrum of Cs2He+ shows three distinct absorption bands into both bound and dissociative states. Upon solvation with further helium atoms, considerable shifts of the absorption bands are observed, exceeding 0.1 eV (850 cm-1) already for Cs2He10+, along with significant broadening. The shifts are highly sensitive to the character of the excited state. Our calculations show that helium atoms adsorb on the ends of Cs2+. The shifts are particularly pronounced if the excited state orbitals extend to the area occupied by the helium atoms. In this case, Pauli repulsion leads to a deformation of the excited state orbitals, resulting in the observed blue shift of the transition. Since the position of the weakly bound helium atoms is ill defined, Pauli repulsion also explains the broadening.
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Affiliation(s)
- Lorenz Kranabetter
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
| | - Nina K Bersenkowitsch
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
| | - Paul Martini
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
| | - Michael Gatchell
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria. and Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
| | - Martin Kuhn
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
| | - Felix Laimer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
| | - Arne Schiller
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
| | - Martin K Beyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
| | - Milan Ončák
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
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Ding EX, Jiang H, Zhang Q, Tian Y, Laiho P, Hussain A, Liao Y, Wei N, Kauppinen EI. Highly conductive and transparent single-walled carbon nanotube thin films from ethanol by floating catalyst chemical vapor deposition. NANOSCALE 2017; 9:17601-17609. [PMID: 29114684 DOI: 10.1039/c7nr05554d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Single-walled carbon nanotube (SWCNT) films have great potential to replace indium tin oxide films for applications in transparent and conductive electronics. Here we report a high yield production of SWCNT transparent conducting films (TCFs) by the floating catalyst chemical vapor deposition method using ethanol as the carbon source. To the best of our knowledge, this is the first report regarding SWCNT TCFs using ethanol as the carbon source. The fabricated uniform SWCNT TCFs exhibit a competitive sheet resistance of 95 Ω sq-1 at 90% transmittance after doping with AuCl3. The SWCNT TCFs possess high quality and the mean length of SWCNT bundles is approximately 27.4 μm. Furthermore, the concentration of semiconducting SWCNTs is 75-77%. Additionally, the chirality maps obtained from electron diffraction analysis demonstrate that our SWCNTs are biased towards the armchair type.
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Affiliation(s)
- Er-Xiong Ding
- Department of Applied Physics, Aalto University School of Science, Puumiehenkuja 2, 00076 Aalto, Espoo, Finland.
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Farrokhpour H, Dehdashti Jahromi M. Absorption spectra of small helium Nano clusters (4He ; n= 2–29) and characterization of their low-lying excited states. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2017.01.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Renzler M, Daxner M, Kranabetter L, Kaiser A, Hauser AW, Ernst WE, Lindinger A, Zillich R, Scheier P, Ellis AM. Communication: Dopant-induced solvation of alkalis in liquid helium nanodroplets. J Chem Phys 2017; 145:181101. [PMID: 27846692 DOI: 10.1063/1.4967405] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Alkali metal atoms and small alkali clusters are classic heliophobes and when in contact with liquid helium they reside in a dimple on the surface. Here we show that alkalis can be induced to submerge into liquid helium when a highly polarizable co-solute, C60, is added to a helium nanodroplet. Evidence is presented that shows that all sodium clusters, and probably single Na atoms, enter the helium droplet in the presence of C60. Even clusters of cesium, an extreme heliophobe, dissolve in liquid helium when C60 is added. The sole exception is atomic Cs, which remains at the surface.
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Affiliation(s)
- Michael Renzler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Matthias Daxner
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Lorenz Kranabetter
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Alexander Kaiser
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Andreas W Hauser
- Institut für Experimentalphysik, Technische Universität Graz, Petergasse 16, A-8010 Graz, Austria
| | - Wolfgang E Ernst
- Institut für Experimentalphysik, Technische Universität Graz, Petergasse 16, A-8010 Graz, Austria
| | - Albrecht Lindinger
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Robert Zillich
- Institut für Theoretische Physik, Johannes Kepler Universität, A-4040 Linz, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Andrew M Ellis
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
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Dehdashti-Jahromi M, Farrokhpour H. Effect of helium nanoclusters on the spectroscopic properties of embedded SF 6: Ionization, excitation and vibration. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 173:772-782. [PMID: 27794241 DOI: 10.1016/j.saa.2016.10.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 06/06/2023]
Abstract
Ionization and excitation energies, IR and Raman spectra of sulfur hexafluoride (SF6), located inside helium (He) nanoclusters with different sizes (SF6@Hen; n=20, 40, 60), were calculated. The effect of the cluster size on the spectroscopic properties of the SF6 was investigated and found that the Hen-SF6 interaction in the He clusters with large number of atoms is small so that the ionization and absorption energies of SF6 are not affected while for small He nanoclusters the Hen-SF6 interaction is more important. The effect of Hen-SF6 interaction and deformation of the fragments on the photoelectron and absorption spectra of SF6@Hen were separated theoretically and discussed in details. It was deduced that the effect of the cluster size on the IR and Raman vibrational frequencies of the SF6 is negligible for the cluster size range considered in this work. Density functional theory (DFT) employing M06-2X functional and 6-31+G(df) basis set were used for optimizing the structures of SF6@Hen. Symmetry adapted cluster-configuration interaction (SAC-CI) methodology, with the same basis set, were used to calculate the ionization and excitation energies of the SF6@Hen structures. Using the calculated ionization and absorption energies and their intensities, the photoelectron and absorption spectra of the considered SF6@Hen structures were simulated and compared with the experiment.
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Affiliation(s)
- M Dehdashti-Jahromi
- Department of Chemistry, Isfahan University of Technology, Isfahan, Iran, 84156-83111
| | - H Farrokhpour
- Department of Chemistry, Isfahan University of Technology, Isfahan, Iran, 84156-83111.
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Kautsch A, Koch M, Ernst WE. Photoinduced molecular dissociation and photoinduced recombination mediated by superfluid helium nanodroplets. Phys Chem Chem Phys 2015; 17:12310-6. [DOI: 10.1039/c5cp01009h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoinduced predissociation of Cr2 in helium nanodroplets causes stable, quantum state specific spatial separation followed by geminate recombination upon photoionization.
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Affiliation(s)
- Andreas Kautsch
- Graz University of Technology
- Institute of Experimental Physics
- NAWI Graz
- A-8010 Graz
- Austria
| | - Markus Koch
- Graz University of Technology
- Institute of Experimental Physics
- NAWI Graz
- A-8010 Graz
- Austria
| | - Wolfgang E. Ernst
- Graz University of Technology
- Institute of Experimental Physics
- NAWI Graz
- A-8010 Graz
- Austria
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Zhang C, Zhang Z, Huang C, Zhang Q, Chen Y. Helium Droplets: An Apparatus to Study Ultra Cold Chemistry. CHINESE J CHEM PHYS 2013. [DOI: 10.1063/1674-0068/26/03/270-276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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9
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Douberly GE, Stiles PL, Miller RE, Schmied R, Lehmann KK. (HCN)(m)-M(n) (M = K, Ca, Sr): vibrational excitation induced solvation and desolvation of dopants in and on helium nanodroplets. J Phys Chem A 2010; 114:3391-402. [PMID: 20151690 DOI: 10.1021/jp908834m] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Infrared (IR) laser spectroscopy is used to probe the rotational and vibrational dynamics of the (HCN)(m)-M(n) (M = K, Ca, Sr) complexes, either solvated within or bound to the surface of helium nanodroplets. The IR spectra of the (HCN)(m)-K (m = 1-3), HCN-Sr, and HCN-Ca complexes have the signature of a surface species, similar to the previously reported spectra of HCN-M (M = Na, K, Rb, Cs) [Douberly, G. E.; Miller, R. E. J. Phys. Chem. A 2007, 111, 7292.]. A second band in the HCN-Ca spectrum is assigned to a solvated complex. The relative intensities of the two HCN-Ca bands are droplet size dependent, with the solvated species being favored in larger droplets. IR-IR double resonance spectroscopy is used to probe the interconversion of the two distinct HCN-Ca populations. While only a surface-bound HCN-Sr species is initially produced, CH stretch vibrational excitation results in a population transfer to a solvated state. Complexes containing multiple HCN molecules and one Sr atom are surface-bound, while the nu(1) (HCN)(2)Ca spectrum has both the solvated and surface-bound signatures. All HCN-(Ca,Sr)(n) (n > or = 2) complexes are solvated following cluster formation in the droplet. Density-functional calculations of helium nanodroplets interacting with the HCN-M show surface binding for M = Na with a binding energy of 95 cm(-1). The calculations predict a fully solvated complex for M = Ca. For M = Sr, a 2.2 cm(-1) barrier is predicted between nearly isoenergetic surface binding and solvated states.
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Affiliation(s)
- Gary E Douberly
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA.
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Koch M, Auböck G, Callegari C, Ernst WE. Coherent spin manipulation and ESR on superfluid helium nanodroplets. PHYSICAL REVIEW LETTERS 2009; 103:035302. [PMID: 19659290 DOI: 10.1103/physrevlett.103.035302] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 06/13/2009] [Indexed: 05/28/2023]
Abstract
Superfluid helium nanodroplets provide a versatile substrate to cool atoms and molecules, and to assemble weakly bound complexes. Absence of spin-relaxation mechanisms makes He nanodroplets ideal to isolate open-shell atoms and create a spin-polarized system. Here, we show the first coherent manipulation of such a system by resonant excitation of a magnetic-dipole transition. Observation of approximately 50 Rabi oscillations demonstrates coherent population transfer with minimal dephasing. Ours is also the first application of ESR spectroscopy to doped He nanodroplets. This unique environment results in extremely sharp lines and hyperfine-resolved spectra: those of single 39K and 85Rb dopant atoms presented here denote an increase of the Fermi contact interaction, which we can follow as a function of droplet size, reflecting the distortion of the valence-electron wave function due to the surrounding He.
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Affiliation(s)
- Markus Koch
- Institute of Experimental Physics, TU Graz, Petersgasse 16, A-8010 Graz, Austria
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Müller S, Krapf S, Koslowski T, Mudrich M, Stienkemeier F. Cold reactions of alkali-metal and water clusters inside helium nanodroplets. PHYSICAL REVIEW LETTERS 2009; 102:183401. [PMID: 19518868 DOI: 10.1103/physrevlett.102.183401] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Indexed: 05/27/2023]
Abstract
The reaction of alkali-metal (Na, Cs) clusters with water clusters embedded in helium nanodroplets is studied using femtosecond photoionization as well as electron-impact ionization. Unlike Na clusters, Cs clusters are found to completely react with water in spite of the ultracold helium droplet environment. Mass spectra of the Csn+(H2O)m reaction products are interpreted in terms of stability with respect to fragmentation using high-level molecular structure calculations.
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Affiliation(s)
- S Müller
- Physikalisches Institut, Universität Freiburg, 79104 Freiburg, Germany
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Auböck G, Nagl J, Callegari C, Ernst WE. Electron spin pumping of Rb atoms on He nanodroplets via nondestructive optical excitation. PHYSICAL REVIEW LETTERS 2008; 101:035301. [PMID: 18764262 DOI: 10.1103/physrevlett.101.035301] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 06/12/2008] [Indexed: 05/26/2023]
Abstract
We measured laser-induced-fluorescence (LIF) and beam-depletion (BD) spectra of rubidium atoms (5S-5P transition) on the surface of superfluid helium nanodroplets (M-He_{N} with M=Rb). It is known that when M is a lighter alkali atom electronic excitation always leads to detachment of the excited atom (M;{*}). The dissociation energy, few tens cm;{-1}, comes either as photon excess energy or from the barrierless formation of a M;{*}-He exciplex. We observe that this picture does not hold when M=Rb and the photon excess energy is small: we are able to excite atoms without detaching them from the droplet, thanks to a barrier preventing formation of the exciplex. This system is ideally suited for optical spin pumping in a He nanodroplet, whose achievement we explicitly demonstrate in a pump-probe magnetic circular dichroism experiment.
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Affiliation(s)
- Gerald Auböck
- Institute of Experimental Physics, TU Graz, Petersgasse 16, 8010 Graz, Austria, EU
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Yang Z, Chen X, Nie H, Zhang K, Li W, Yi B, Xu L. Direct synthesis of ultralong carbon nanotube bundles by spray pyrolysis and investigation of growth mechanism. NANOTECHNOLOGY 2008; 19:085606. [PMID: 21730730 DOI: 10.1088/0957-4484/19/8/085606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A mass of ultralong aligned carbon nanotube (CNT) bundles up to about 8 mm in length was synthesized by utilizing the spray pyrolysis of ferrocene/xylene solutions in the absence of promoters, such as thiophene or pure sulfur, and etching agents, such as plasma, oxygen, ethanol or water. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) results indicated the continuous and multi-walled nanotube structure for the CNTs in the macroscopical bundles. A graph demonstrating the correlation between growth time and length of CNT arrays revealed that the maximum growth rate reaches approximately 4612 nm s(-1). Based on the experimental phenomena and results, a continuous rapid growth mechanism in both directions was proposed, which suggests that longer CNT arrays can be synthesized at this rapid growth rate if the growth time is extended.
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Affiliation(s)
- Zhi Yang
- College of Materials Science and Engineering, Hunan University, Changsha 410082, People's Republic of China
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