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Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics. Nat Commun 2016; 7:11652. [PMID: 27212390 PMCID: PMC4879250 DOI: 10.1038/ncomms11652] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 04/18/2016] [Indexed: 11/09/2022] Open
Abstract
New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Particularly, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. Here we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ions during the fragmentation of XeF2 molecules following X-ray absorption at the Xe site.
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Guest–Host Interactions Investigated by Time-Resolved X-ray Spectroscopies and Scattering at MHz Rates: Solvation Dynamics and Photoinduced Spin Transition in Aqueous Fe(bipy)32+. J Phys Chem A 2012; 116:9878-87. [DOI: 10.1021/jp306917x] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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3
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Unveiling and driving hidden resonances with high-fluence, high-intensity x-ray pulses. PHYSICAL REVIEW LETTERS 2011; 107:233001. [PMID: 22182083 DOI: 10.1103/physrevlett.107.233001] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Indexed: 05/24/2023]
Abstract
We show that high fluence, high-intensity x-ray pulses from the world's first hard x-ray free-electron laser produce nonlinear phenomena that differ dramatically from the linear x-ray-matter interaction processes that are encountered at synchrotron x-ray sources. We use intense x-ray pulses of sub-10-fs duration to first reveal and subsequently drive the 1s↔2p resonance in singly ionized neon. This photon-driven cycling of an inner-shell electron modifies the Auger decay process, as evidenced by line shape modification. Our work demonstrates the propensity of high-fluence, femtosecond x-ray pulses to alter the target within a single pulse, i.e., to unveil hidden resonances, by cracking open inner shells energetically inaccessible via single-photon absorption, and to consequently trigger damaging electron cascades at unexpectedly low photon energies.
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Nonlinear atomic response to intense ultrashort x rays. PHYSICAL REVIEW LETTERS 2011; 106:083002. [PMID: 21405568 DOI: 10.1103/physrevlett.106.083002] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Indexed: 05/11/2023]
Abstract
The nonlinear absorption mechanisms of neon atoms to intense, femtosecond kilovolt x rays are investigated. The production of Ne(9+) is observed at x-ray frequencies below the Ne(8+), 1s(2) absorption edge and demonstrates a clear quadratic dependence on fluence. Theoretical analysis shows that the production is a combination of the two-photon ionization of Ne(8+) ground state and a high-order sequential process involving single-photon production and ionization of transient excited states on a time scale faster than the Auger decay. We find that the nonlinear direct two-photon ionization cross section is orders of magnitude higher than expected from previous calculations.
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Double core-hole production in N2: beating the Auger clock. PHYSICAL REVIEW LETTERS 2010; 105:083005. [PMID: 20868097 DOI: 10.1103/physrevlett.105.083005] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Indexed: 05/29/2023]
Abstract
We investigate the creation of double K-shell holes in N2 molecules via sequential absorption of two photons on a time scale shorter than the core-hole lifetime by using intense x-ray pulses from the Linac Coherent Light Source free electron laser. The production and decay of these states is characterized by photoelectron spectroscopy and Auger electron spectroscopy. In molecules, two types of double core holes are expected, the first with two core holes on the same N atom, and the second with one core hole on each N atom. We report the first direct observations of the former type of core hole in a molecule, in good agreement with theory, and provide an experimental upper bound for the relative contribution of the latter type.
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Femtosecond electronic response of atoms to ultra-intense X-rays. Nature 2010; 466:56-61. [PMID: 20596013 DOI: 10.1038/nature09177] [Citation(s) in RCA: 259] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 05/10/2010] [Indexed: 11/09/2022]
Abstract
An era of exploring the interactions of high-intensity, hard X-rays with matter has begun with the start-up of a hard-X-ray free-electron laser, the Linac Coherent Light Source (LCLS). Understanding how electrons in matter respond to ultra-intense X-ray radiation is essential for all applications. Here we reveal the nature of the electronic response in a free atom to unprecedented high-intensity, short-wavelength, high-fluence radiation (respectively 10(18) W cm(-2), 1.5-0.6 nm, approximately 10(5) X-ray photons per A(2)). At this fluence, the neon target inevitably changes during the course of a single femtosecond-duration X-ray pulse-by sequentially ejecting electrons-to produce fully-stripped neon through absorption of six photons. Rapid photoejection of inner-shell electrons produces 'hollow' atoms and an intensity-induced X-ray transparency. Such transparency, due to the presence of inner-shell vacancies, can be induced in all atomic, molecular and condensed matter systems at high intensity. Quantitative comparison with theory allows us to extract LCLS fluence and pulse duration. Our successful modelling of X-ray/atom interactions using a straightforward rate equation approach augurs favourably for extension to complex systems.
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Ultraintense x-ray induced ionization, dissociation, and frustrated absorption in molecular nitrogen. PHYSICAL REVIEW LETTERS 2010; 104:253002. [PMID: 20867372 DOI: 10.1103/physrevlett.104.253002] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Indexed: 05/11/2023]
Abstract
Sequential multiple photoionization of the prototypical molecule N2 is studied with femtosecond time resolution using the Linac Coherent Light Source (LCLS). A detailed picture of intense x-ray induced ionization and dissociation dynamics is revealed, including a molecular mechanism of frustrated absorption that suppresses the formation of high charge states at short pulse durations. The inverse scaling of the average target charge state with x-ray peak brightness has possible implications for single-pulse imaging applications.
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Low-energy nondipole effects in molecular nitrogen valence-shell photoionization. PHYSICAL REVIEW LETTERS 2006; 97:103006. [PMID: 17025814 DOI: 10.1103/physrevlett.97.103006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Indexed: 05/12/2023]
Abstract
Observations are reported for the first time of significant nondipole effects in the photoionization of the outer-valence orbitals of diatomic molecules. Measured nondipole angular-distribution parameters for the 3sigma(g), 1pi(u), and 2sigma(u) shells of N2 exhibit spectral variations with incident photon energies from thresholds to approximately 200 eV which are attributed via concomitant calculations to particular final-state symmetry waves arising from (E1)multiply sign in circle(M1,E2) radiation-matter interactions first-order in photon momentum. Comparisons with previously reported K-edge studies in N2 verify linear scaling with photon momentum, accounting in part for the significantly enhanced nondipole behavior observed in inner-shell ionization at correspondingly higher momentum values in this molecule.
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X-ray microprobe of orbital alignment in strong-field ionized atoms. PHYSICAL REVIEW LETTERS 2006; 97:083601. [PMID: 17026302 DOI: 10.1103/physrevlett.97.083601] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Indexed: 05/12/2023]
Abstract
We have developed a synchrotron-based, time-resolved x-ray microprobe to investigate optical strong-field processes at intermediate intensities (10(14) - 10(15) W/cm2). This quantum-state specific probe has enabled the direct observation of orbital alignment in the residual ion produced by strong-field ionization of krypton atoms via resonant, polarized x-ray absorption. We found strong alignment to persist for a period long compared to the spin-orbit coupling time scale (6.2 fs). The observed degree of alignment can be explained by models that incorporate spin-orbit coupling. The methodology is applicable to a wide range of problems.
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Dramatic nondipole effects in low-energy photoionization: experimental and theoretical study of Xe 5s. PHYSICAL REVIEW LETTERS 2003; 91:053002. [PMID: 12906593 DOI: 10.1103/physrevlett.91.053002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2003] [Indexed: 05/24/2023]
Abstract
The Xe 5s nondipole photoelectron parameter gamma is obtained experimentally and theoretically from threshold to approximately 200 eV photon energy. Significant nondipole effects are seen even in the threshold region of this valence shell photoionization. In addition, contrary to previous understanding, clear evidence of interchannel coupling among quadrupole photoionization channels is found.
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11
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Photoexcitation of a dipole-forbidden resonance in helium. PHYSICAL REVIEW LETTERS 2002; 88:203002. [PMID: 12005562 DOI: 10.1103/physrevlett.88.203002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2001] [Indexed: 05/23/2023]
Abstract
We have observed photoexcitation of the dipole-forbidden 1s(2) 1S0-->2p(2) 1D2 resonance in helium by measuring the nondipolar forward-backward asymmetry of photoelectron angular distributions in the 2l2l(') autoionizing region. By exploiting the electric dipole-quadrupole interference in the excitation of both the 2s2p 1P1 and 2p(2) 1D2 levels, we have observed the quadrupole resonance in photoabsorption and extracted its Fano line shape parameters and the relative phase of the 1sEp and 1sEd continua. We find the quadrupole line profile index q(2) to be markedly different from theoretical expectations.
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Strong evidence for enhanced multiple electron capture from surfaces in 46 MeV/u Pb81+ collisions with thin carbon foils. PHYSICAL REVIEW LETTERS 2001; 86:991-994. [PMID: 11177992 DOI: 10.1103/physrevlett.86.991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2000] [Indexed: 05/23/2023]
Abstract
Strong evidence has been found for enhanced multiple electron capture into 46 MeV/u Pb81+ with a significant contribution from the entrance surface of thin carbon foils. Capture of up to five electrons has been observed. The multiple electron capture yield is found to increase with decreasing target thickness for thin targets. A simple model describing the data and showing the importance of capture from surfaces is discussed. Further evidence is found for a pronounced asymmetry between electron capture at the entrance and the exit surfaces. Absolute yields for multiple electron capture and projectile ionization are presented. The experimental total cross sections for single capture and ionization agree well with theory.
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Ionization and fragmentation of C60 by highly charged, high-energy xenon ions. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1996; 54:3182-3194. [PMID: 9913839 DOI: 10.1103/physreva.54.3182] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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15
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Experimental determination of nondipolar angular distribution parameters for photoionization in the Ar K and Kr L shells. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1996; 54:2127-2136. [PMID: 9913703 DOI: 10.1103/physreva.54.2127] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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16
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Fully Differential Cross Sections for Double Photoionization of He Measured by Recoil Ion Momentum Spectroscopy. PHYSICAL REVIEW LETTERS 1996; 77:1024-1027. [PMID: 10062971 DOI: 10.1103/physrevlett.77.1024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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17
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Dielectronic recombination and energy loss for He-like 79Br ions channeled in a thin single crystal of Si. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1996; 54:624-635. [PMID: 9913516 DOI: 10.1103/physreva.54.624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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18
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Ratio of cross sections for double to single ionization of He by 85-400 eV photons. PHYSICAL REVIEW LETTERS 1996; 76:2654-2657. [PMID: 10060755 DOI: 10.1103/physrevlett.76.2654] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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19
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Nondipolar asymmetries of photoelectron angular distributions. PHYSICAL REVIEW LETTERS 1995; 75:4736-4739. [PMID: 10059984 DOI: 10.1103/physrevlett.75.4736] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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20
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Half-lives of isomeric states in 57Fe and 83Kr. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1995; 52:2240-2241. [PMID: 9970741 DOI: 10.1103/physrevc.52.2240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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21
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Fine-structure energies for the 1s2s 3S-1s2p 3P transition in heliumlike Ar16+. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1995; 51:1905-1917. [PMID: 9911800 DOI: 10.1103/physreva.51.1905] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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22
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Measurement of the lifetime of the 2 (3)P2 state in heliumlike krypton using a two-foil target. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1994; 50:2197-2201. [PMID: 9911131 DOI: 10.1103/physreva.50.2197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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23
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Ionization and multifragmentation of C60 by high-energy, highly charged Xe ions. PHYSICAL REVIEW LETTERS 1994; 72:3965-3968. [PMID: 10056345 DOI: 10.1103/physrevlett.72.3965] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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24
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Experimental evidence for anomalous nuclear delocalization in C2H3+. PHYSICAL REVIEW LETTERS 1993; 71:4319-4322. [PMID: 10055216 DOI: 10.1103/physrevlett.71.4319] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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25
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Two-photon decay of the 2 (1)S0 state in He-like bromine. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1993; 48:1929-1936. [PMID: 9909809 DOI: 10.1103/physreva.48.1929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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26
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Direct observation of nuclear rearrangement in molecules. PHYSICAL REVIEW LETTERS 1993; 70:3549-3552. [PMID: 10053902 DOI: 10.1103/physrevlett.70.3549] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Experimental transition probabilities of intercombination transitions in Mg-like and Al-like ions of bromine. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1993; 47:3805-3809. [PMID: 9909387 DOI: 10.1103/physreva.47.3805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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29
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Branching ratio for the M1 decay of the 2 (2)S1/2 state in one-electron krypton. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1993; 47:903-910. [PMID: 9909009 DOI: 10.1103/physreva.47.903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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30
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Influence of multiple scattering on the Coulomb-explosion imaging of fast molecules. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1992; 46:194-200. [PMID: 9907848 DOI: 10.1103/physreva.46.194] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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31
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32
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33
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Sensitivity of Coulomb-explosion images to the shapes of molecular potentials: The case of He22+. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1991; 43:1608-1610. [PMID: 9905188 DOI: 10.1103/physreva.43.1608] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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34
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Multiple scattering of MeV atomic and molecular ions traversing ultrathin films. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1990; 41:2482-2488. [PMID: 9903380 DOI: 10.1103/physreva.41.2482] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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35
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High-resolution study of dielectronic capture by channeled Ti ions. PHYSICAL REVIEW LETTERS 1990; 64:380-383. [PMID: 10041965 DOI: 10.1103/physrevlett.64.380] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Abstract
Most of our knowledge of the structures of free molecules comes from indirect observations that focus on other properties (for example, energy or mass spectra) that depend on structure. Recently, a new method has been developed that instead yields geometrical images of individual molecules. This method takes advantage of the large Coulomb repulsion of the nuclei within molecules rapidly stripped of their electrons. The first experiments with this new technique have already revealed structural images of several important species, such as positively charged methane ions.
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38
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A measurement of the low energy stereostructure of protonated acetylene, C2H+3. J Chem Phys 1986. [DOI: 10.1063/1.451338] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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39
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Direct determination of the stereochemical structure of CH4+. PHYSICAL REVIEW LETTERS 1986; 57:2793-2795. [PMID: 10033867 DOI: 10.1103/physrevlett.57.2793] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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40
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Charge-state distributions of nitrogen ions resulting from the foil-induced dissociation of 4.2-MeV N2 + ions. PHYSICAL REVIEW. A, GENERAL PHYSICS 1985; 32:105-111. [PMID: 9896030 DOI: 10.1103/physreva.32.105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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