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Sökning: WFRF:(Bjorneholm O)

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1.
  • Burmeister, F., et al. (författare)
  • A study of the inner-valence ionization region in HCl and DCl
  • 2004
  • Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 37:6, s. 1173-1183
  • Tidskriftsartikel (refereegranskat)abstract
    • An in-depth photoionization study of the inner-valence electrons in HCl and DCl has been performed using synchrotron radiation. A series of photoelectron spectra of HCl were obtained at a resolution of 23 meV over the binding energy range 25-30.5 eV at various excitation energies and at two different electron collection angles relative to the plane of polarization of the undulator radiation. In addition, photoelectron spectra of DCl were recorded at two different excitation energies. These spectra were compared directly with the threshold photoelectron spectra of HCl and DCl that were recorded previously under similar resolution conditions (similar to30 meV). This comparative study reveals new information on the nature of the numerous band systems observed in this binding energy region. In addition, we present the experimental confirmation of the theoretical prediction given by Andersson et al (2001 Phys. Rev. A 65 012705) that a vibrational progression showing interference structure would appear in the main inner-valence ionization band in the photoelectron spectrum of DCl at a resolution of 10 meV.
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2.
  • Sandell, A., et al. (författare)
  • THE INNER VALENCE REGION OF CO ADSORBED ON PD(100)
  • 1994
  • Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 26:19, s. 10659-10668
  • Tidskriftsartikel (refereegranskat)abstract
    • The inner valence region of CO/Pd(100) p(2square-root2 x square-root2)R45-degrees has been studied by angular resolved photoemission at the Pd 4d Cooper minimum, and with resonant Auger spectroscopy at photon energies corresponding to the C 1s and O 1s x-ray absorption (XA) maxima of the unoccupied parts of the 2pi*-Pd 4d hybrid (2pi(un)). Previously unobserved inner valence states are revealed in the direct photoemission and are compared with resonant Auger results. The interpretation and assignment of the different spectral features to different main final state configurations are based on energy, symmetry and intensity arguments, as well as comparisons with previous results.
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3.
  • Abu-samha, M, et al. (författare)
  • Lineshapes in carbon 1s photoelectron spectra of methanol clusters
  • 2006
  • Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084. ; 8:21, s. 2473-2482
  • Tidskriftsartikel (refereegranskat)abstract
    • A general protocol for theoretical modeling of inner-shell photoelectron spectra of molecular clusters is presented and applied to C1s spectra of oligomers and medium-sized clusters of methanol. The protocol employs molecular dynamics for obtaining cluster geometries and a polarizable force field for computing site-specific chemical shifts in ionization energy and linewidth. Comparisons to spectra computed from first-principle theories are used to establish the accuracy of the proposed force field approach. The model is used to analyze the C1s photoelectron spectrum of medium-sized clusters in terms of surface and bulk contributions. By treating the surface-to-bulk ratio as an adjustable parameter, satisfactory fits are obtained to experimental C1s spectra of a beam of methanol clusters.
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4.
  • Ausmees, A, et al. (författare)
  • Observation of excitation-energy-dependent Xe 4d(5/2,3/2)(-1) lifetime widths
  • 1999
  • Ingår i: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP PUBLISHING LTD. ; 32:9
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • The creation and decay of photon-excited Xe 4d(5/2,3/2)(-1) core-hole states has been studied in the photon energy region 70-110 eV, where photon absorption is dominated by the strong shape resonance. Unprecedented experimental quality has enabled the stu
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5.
  • Baev, A., et al. (författare)
  • Geometrical information on core-excited states obtained from interference quenching of vibrational states in resonant x-ray photoemission
  • 2003
  • Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 67:2
  • Tidskriftsartikel (refereegranskat)abstract
    • An interference quenching of the m=1 final state vibrational line in the resonant Auger decay of N 1s-->pi(*) core-excited N-2 is observed and analyzed. The intensity ratio between the m=1 and m=0 vibrational levels of the X (2)Sigma(g)(+) final state shows a surprising nonmonotonic variation as a function of frequency detuning, going through a minimum with a complete suppression of m=1. We have developed a simple model which indicates a linear relation between the value of the detuning frequency for this minimum and the equilibrium bond distance of the core-excited state. This implies the possibility of determining the equilibrium bond distances for core-excited states to a high degree of accuracy. Simultaneously with the simple model we present a strict theory of the studied effect. This strict theory allows us to explore the accuracy of determining the bond length of the core-excited state from resonant Auger spectra. We obtain a weak influence of the core-hole lifetime on the determined bond length, whereas the number of intermediate vibrational states accounted for in the numerical simulations seems to be quite important.
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6.
  • Bassler, M, et al. (författare)
  • Beam line 1411 at MAX II - performance and first results
  • 2001
  • Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT. - : ELSEVIER SCIENCE BV. - 0168-9002. ; 469:3, s. 382-393
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the characteristics and first results from the soft X-ray beam line I411, based on an undulator at the third generation synchrotron facility MAX II, Sweden. The beam line is designed for high-resolution, angle-resolved electron spectroscopy o
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7.
  • Bassler, M, et al. (författare)
  • Soft X-ray undulator beam line I411 at MAX-II for gases, liquids and solid samples
  • 1999
  • Ingår i: JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA. - : ELSEVIER SCIENCE BV. - 0368-2048. ; 103, s. 953-957
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • We report on the build-up of the new undulator beam line I411 at the third-generation synchrotron radiation facility MAX II in Lund, Sweden. This beam line is based on an upgraded version of the modified SX700-monochromator and the end station which were
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8.
  • Bjorneholm, O, et al. (författare)
  • Between vapor and ice: Free water clusters studied by core level spectroscopy
  • 1999
  • Ingår i: JOURNAL OF CHEMICAL PHYSICS. - : AMER INST PHYSICS. - 0021-9606. ; 111:2, s. 546-550
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Core level x-ray absorption and photoemission spectra of free water clusters are presented. Core and valence photoemission spectra show a weak but gradual change with cluster size. Comparisons to spectra of the isolated molecule and solid ice indicate tha
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9.
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10.
  • Bjorneholm, O, et al. (författare)
  • Femtosecond dissociation of core-excited HCl monitored by frequency detuning
  • 1997
  • Ingår i: PHYSICAL REVIEW LETTERS. - : AMER INST PHYSICS. - 0031-9007. ; 79:17, s. 3150-3153
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Core excitation of gaseous HCl to the dissociative sigma* state leads to a deexcitation spectrum with two qualitatively different contributions-a broad molecular background and narrow atomic lines. The experiment demonstrates that the ratio of integrated
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11.
  • Burmeister, F, et al. (författare)
  • Nonadiabatic effects in photoelectron spectra of HCl and DCl. I. Experiment
  • 2002
  • Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 65:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The HCl inner-valence photoelectron band at 26 eV binding energy has been recorded at high resolution. Discrete peaks arising from at least two separate vibrational progressions are superimposed on the broad continuum. Fano profiles are visible in one of the progressions. This indicates interference between superimposed electronic states, where weak avoided crossing allows two adiabatic states to couple. In the isotopic DCl molecular spectrum, the discrete lines are less pronounced, due to slower dissociation and therefore less coupling between the continuum and the bound state.
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12.
  • Carravetta, V, et al. (författare)
  • Excitation-energy-dependent resonant photoemission: C1s-pi* spectra of carbon monoxide
  • 1997
  • Ingår i: PHYSICAL REVIEW A. - : AMER INST PHYSICS. - 1050-2947. ; 56:6, s. 4665-4674
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • High-resolution measurements of the x-ray resonant photoemission of CO near the C1s-->pi* transition are presented. The branching ratios for the valence shell ionization close to the resonance how a strong dependence on the photon energy with a clear asym
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13.
  • de, Brito AN, et al. (författare)
  • Femtosecond dissociation dynamics of core-excited molecular water
  • 1999
  • Ingår i: CHEMICAL PHYSICS LETTERS. - : ELSEVIER SCIENCE BV. - 0009-2614. ; 309:5-6, s. 377-385
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The fragmentation of the water molecule upon resonant core excitation and subsequent Auger decay has been studied by electron-ion coincidence spectroscopy. A qualitative comparison between the fragmentation patterns for H2O and D2O reveals that the anti-b
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14.
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15.
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16.
  • Feifel, R, et al. (författare)
  • A quantitative analysis of the N 1s ->pi* photoabsorption profile in N-2: new spectroscopical constants for the core-excited state
  • 2004
  • Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 383:3-4, s. 222-229
  • Tidskriftsartikel (refereegranskat)abstract
    • The N 1s --> pi* photoabsorption profile of N-2 is quantitatively analysed. New spectroscopical constants for the N 1s(-1) pi* core-excited state are determined from NEXAFS spectra and compared to previously published data. The accuracy of the new spectroscopical constants is discussed and error bars are given for the present data analysis. The goodness of the new spectroscopical constants is demonstrated by lifetime vibrational interference (LVI) simulations of the resonant Auger decay from the N 1s(-1) pi* core-excited state to the A(2)Pi(u) singly ionized final state of N-2. These new values give a much better agreement with recently obtained experimental data compared to the previously published ones.
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17.
  • Feifel, R., et al. (författare)
  • Interference quenching of nu('')=1 vibrational line in resonant photoemission of N-2 : A possibility to obtain geometrical information on the core-excited state
  • 2002
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 89:10
  • Tidskriftsartikel (refereegranskat)abstract
    • An interference quenching of the nu=1 vibrational line in the resonant Auger decay of N 1s-->pi(*) core-excited N-2 is observed and analyzed. The intensity ratio between the nu=1 and nu=0 vibrational levels of the X(2)Sigma(g)(+) final state shows a surprising nonmonotonous variation as a function of frequency detuning, going through a minimum with a complete suppression of nu=1. We have developed a simple model which shows a linear relation between the value of the detuning frequency for this minimum and the equilibrium bond distance R-c(0) of the core-excited state. A new way is thus established of determining the equilibrium bond distance for the core-excited state with a precision deltaR(c)(0)<10(-3) Angstrom.
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18.
  • Feifel, R, et al. (författare)
  • Observation of a continuum-continuum interference hole in ultrafast dissociating core-excited molecules
  • 2000
  • Ingår i: Physical Review Letters. - : AIP Publishing. - 0031-9007 .- 1079-7114. ; 85:15, s. 3133-3136
  • Tidskriftsartikel (refereegranskat)abstract
    • The femtosecond dissociation of HCl after core excitation has been studied through the resonant Auger decay. The spectra contain contributions from decay occurring at both "molecular" and "atomic" internuclear distances. We have observed a new interference mechanism in these spectra: An atomic spectral line develops into a negative spectral contribution, a "hole," when detuning the excitation energy from the maximum of the Cl 2p(-1)sigma* resonance. Resonant x-ray scattering theory quantitatively explains this behavior as due to a novel destructive continuum-Continuum interference between molecular and atomic contributions to the Auger decay.
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19.
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20.
  • Feifel, R, et al. (författare)
  • Probing doubly excited ionic states of N-2(+) via a triple excitation above the N 1s threshold in the N-2 molecule
  • 2003
  • Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 67:3: 032504
  • Tidskriftsartikel (refereegranskat)abstract
    • Angle-resolved resonant Auger-electron spectroscopy has been carried out on the nitrogen molecule at selected photon energies around 419 eV, where a 1s core electron and two valence electrons are promoted into the lowest unoccupied molecular orbital 1pi(g). Significant enhancement of a specific band, which cannot be disentangled in direct photoionization, is observed at a binding energy of 37.6 eV, with a value of the anisotropy parameter beta much smaller than 2. We assign this new band to the transition to a doubly excited cationic state of N-2, in which two of the excited valence electrons remain in the 1pi(g) orbital, proposing a "double spectator" type decay mechanism. This observation shows how to preferentially probe multiply excited configurations of cations using multiple resonant excitation.
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21.
  • Feifel, R., et al. (författare)
  • Role of stray light in the formation of high-resolution resonant photoelectron spectra : an experimental and theoretical study of N-2
  • 2004
  • Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 134:1, s. 49-65
  • Tidskriftsartikel (refereegranskat)abstract
    • We show that the undular stray light, diffusely scattered by the optical system of a synchrotron beamline, can play an important role in the formation of high-resolution resonant photoelectron (RPE) spectra. The influence of the stray light is mediated through the Stokes doubling effect, with the Lorentzian tail of the spectral function being replaced by a more complicated form. This effect is shown to appear in the high-resolution resonant photoelectron spectrum of the N-2 molecule in which the spectral shape of the non-Raman (NR) bands differs qualitatively for the A(2)Pi(u) and X(2)Sigma(g)(+) final states. A particularly large enhancement of the non-Raman Stokes line is observed for the A-state while the picture is inverted for the X-state where the non-Raman band is suppressed. It is shown that the resonant photoemission profile is affected by two qualitatively different detunings, the detuning of the monochromatized line relative to the photoabsorption line and the detuning of the undulator harmonic relative to the same reference line. The experimental data show that the relative intensity of the non-Raman line strongly depends on the tuning of the undulator harmonic with respect to the selected monochromator bandpass, leading to a strong decrease of the Stokes line intensity for certain undulator detunings. A clear red-shift asymmetry for the decrease in the Stokes line intensity is observed when the monochromator line is detuned towards negative photon frequencies, whereas the picture is reverted for the situation of a positively detuned monochromator line. The results show the necessity to control the stray light and to investigate both the Raman and non-Raman contributions to the spectral profiles in order to avoid misinterpretation and in order to make full use of the information available in resonant photoemission spectra of molecules.
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22.
  • Fink, RF, et al. (författare)
  • Spin-orbit selectivity observed for the HCl+ ((X)over-tilde (II)-I-2) state using resonant photoemission
  • 2002
  • Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 65:3
  • Tidskriftsartikel (refereegranskat)abstract
    • We report the experimental observation of a strongly selective population of the spin-orbit components in the HCl+ (X) over tilde (2)Pi(Omega) states after excitation into the dissociative 2p(-1)6sigma* core excited state. A progression of highly excited vibrational states with either the Omega=3/2 or Omega=1/2 component of the final state is populated, respectively, when the excitation is tuned in the 2p(3/2)(-1)6sigma*or2p(1/2)(-1)6 sigma* part of the resonance. This effect is explained theoretically to be due to the orientational selectivity of the excitation process and the preference of the L-2,L-3 VV Auger process to produce valence holes with the same orientation as the core holes.
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23.
  • Gisselbrecht, Mathieu, et al. (författare)
  • Photon energy dependence of fragmentation of small argon clusters
  • 2005
  • Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 123:19
  • Tidskriftsartikel (refereegranskat)abstract
    • Photofragmentation of small argon clusters with size below ten atoms is reported. In this size range significant modifications from the electronic properties and geometry take place. When tuning the photon energy through the argon 2p edge, the fragmentation pattern is changed. Specifically, cation dimer production is enhanced at the 2p(3/2)-> 4s resonance, while above the 2p edge almost complete atomization is observed. In both cases, the widths of the peaks in the mass spectra indicate that a large amount of kinetic energy is imparted to the fragment due to the formation of multiply charged clusters. A model based on "Coulomb explosion"-charge separation, simply resulting in a complete atomization of the cluster with no dependence on the photon energy-is insufficient to explain the observed photofragmentation of small clusters.
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24.
  • Hjelte, I, et al. (författare)
  • Evidence for ultra-fast dissociation of molecular water from resonant Auger spectroscopy
  • 2001
  • Ingår i: CHEMICAL PHYSICS LETTERS. - : ELSEVIER SCIENCE BV. - 0009-2614. ; 334:1-3, s. 151-158
  • Tidskriftsartikel (refereegranskat)abstract
    • We present direct evidence for ultra-fast dissociation of molecular water in connection photo-excitation of the Ols --> 4a(1) resonance. The core-excited H2O molecules are shown to dissociate into core-excited O*H and neutral H on a time scale comparable
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25.
  • Hjelte, I, et al. (författare)
  • Evidence of ultra-fast dissociation in ammonia observed by resonant Auger electron spectroscopy
  • 2003
  • Ingår i: Chemical Physics Letters. - 0009-2614. ; 370:5-6, s. 781-788
  • Tidskriftsartikel (refereegranskat)abstract
    • We present evidence for ultra-fast dissociation of molecular ammonia when photo-excited to the Nls --> 4a(1) core-hole state. This finding is based on resonant Auger spectroscopical results as well as qualitative arguments concerning the photon energy dependence of the Auger structures. Calculations of the excited state potential based on the Z + l approximation were performed. Both the calculations and the measurements indicate that the most likely fragmentation pathway for the core excited ammonia molecules leads to NH2* and H fragments. (C) 2003 Elsevier Science B.V. All rights reserved.
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26.
  • Kaiser, L., et al. (författare)
  • Angular emission distribution of O 1s photoelectrons of uniaxially oriented methanol
  • 2020
  • Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 53:19
  • Tidskriftsartikel (refereegranskat)abstract
    • The angular distribution of O 1s photoelectrons emitted from uniaxially oriented methanol is studied experimentally and theoretically. We employed circularly polarized photons of an energy ofh nu= 550 eV for our investigations. We measured the three-dimensional photoelectron angular distributions of methanol, with the CH3-OH axis oriented in the polarization plane, by means of cold target recoil ion momentum spectroscopy. The experimental results are interpreted by single active electron calculations performed with the single center method. A comparative theoretical study of the respective molecular-frame angular distributions of O 1s photoelectrons of CO, performed for the same photoelectron kinetic energy and for a set of different internuclear distances, allows for disentangling the role of internuclear distance and the hydrogen atoms of methanol as compared to carbon monoxide.
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27.
  • Kivimäki, A, et al. (författare)
  • Resonant Auger spectroscopy of argon clusters at the 2p threshold
  • 2005
  • Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 71:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Resonant Auger spectra of large argon clusters have been measured at the Ar 2p edge. The decay spectra can give some information on the states reached in photon absorption. For example, the observation of the 3p(4)4p final states indicates the occurrence of the 2p(3/2)-> 4p excitation in clusters, whereas in atoms this excitation is dipole forbidden. Also the 3p(4)3d final states are identified in the resonant Auger spectra. A peculiar finding is that the normal Auger transitions in bulk cluster atoms are observed below the 2p ionization thresholds. This is explained by the excitation of the 2p electrons into the conduction band, followed by a rapid delocalization of the electron.
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28.
  • Lindblad, A, et al. (författare)
  • Postcollision interaction in noble gas clusters: Observation of differences in surface and bulk line shapes
  • 2005
  • Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 123:21
  • Tidskriftsartikel (refereegranskat)abstract
    • The surface and bulk components of the x-ray photoelectron spectra of free noble gas clusters are shown to display differences in the influence of postcollision interaction between the photoelectron and the Auger electron on the spectral line shape; the bulk component is observed to be less affected than the surface and atomic parts of the spectra. A model for postcollision interaction in nonmetallic solids and clusters is also provided which takes the polarization screening into account. Core-level photoelectron spectra of Ar, Kr, and Xe have been recorded to verify the dependence of the postcollision interaction effect on the polarizability of the sample.
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29.
  • Lindblad, A, et al. (författare)
  • The far from equilibrium structure of argon clusters doped with krypton or xenon
  • 2006
  • Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084. ; 8:16, s. 1899-1905
  • Tidskriftsartikel (refereegranskat)abstract
    • Heterogeneous clusters created by doping Ar host clusters with Kr or Xe are shown to have radically different structures from the mixed clusters of the same type created by co-expansion of Ar-Kr or Ar-Xe gas mixtures. In contrast to the co-expansion case, the doped mixed clusters can be produced with Kr or Xe on the surface and Ar in the bulk. With the doping technique it is thus possible to control the surface composition of a specific cluster. A study of the cluster properties as a function of the doping pressure is also reported for the case of Ar clusters doped with Xe. The clusters have been studied by means of synchrotron radiation based X-ray photoelectron spectroscopy.
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30.
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31.
  • Lundwall, M, et al. (författare)
  • Enhanced surface sensitivity in AES relative to XPS observed in free argon clusters
  • 2005
  • Ingår i: Surface Science. - : Elsevier BV. - 0039-6028. ; 594:1-3, s. 12-19
  • Tidskriftsartikel (refereegranskat)abstract
    • The surface-to-bulk intensity ratio in Auger electron spectra has been studied in comparison with core-level photoelectron spectra using free argon clusters of sizes ranging over two orders of magnitude. Enhanced surface sensitivity is observed in L2,3M2,3M2.3 Auger electron spectra compared to 2p photoelectron spectra where electrons of similar kinetic energies were recorded. This is discussed in terms of the effective attenuation length of the electrons.
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32.
  • Lundwall, M., et al. (författare)
  • Preferential site occupancy of krypton atoms on free argon-cluster surfaces
  • 2006
  • Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 125:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Argon clusters have been doped with krypton atoms in a pick-up setup and investigated by means of ultraviolet and x-ray photoelectron spectroscopy (UPS and XPS). The width of the krypton surface feature in the XPS spectra from mixed krypton/argon clusters has been studied and found to be narrower than in the case of homogeneous krypton clusters. By considering known spectral broadening mechanisms of the cluster features and the electron binding energy shift of the cluster surface feature relative to the atomic signal, we conclude that krypton ad-atoms preferentially occupy high-coordination surface sites on the argon host-cluster. (c) 2006 American Institute of Physics.
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33.
  • Lundwall, M, et al. (författare)
  • Radial surface segregation in free heterogeneous argon/krypton clusters
  • 2004
  • Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 392:4-6, s. 433-438
  • Tidskriftsartikel (refereegranskat)abstract
    • Free clusters produced by a co-expansion of argon and krypton have been studied by means of core level photoelectron spectroscopy. In this study we have determined: (i) the produced clusters are heterogeneous; (ii) the radial distribution of the two atomic species in the cluster differs. The proposed structure model places the majority of the krypton atoms in the bulk, leaving the argon atoms to be found more frequently on the cluster surface. The suggested structure is qualitatively discussed using the cohesive energies of the two-components. (C) 2004 Elsevier B.V. All rights reserved.
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34.
  • Lundwall, M., et al. (författare)
  • Shell-dependent core-level chemical shifts observed in free xenon clusters
  • 2006
  • Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 39:24, s. 5225-5235
  • Tidskriftsartikel (refereegranskat)abstract
    • Photoelectron and Auger electron spectra following Xe-3d and Xe-4d ionization of free xenon clusters have been measured using synchrotron radiation. The atom-to-surface and atom-to-bulk binding energy shifts found in the Xe-3d and the subsequent M5N4,5N4,5 Auger decay are about 15% larger than those observed in the Xe-4d and N4,5O2,3O2,3 measurements. This experimental result is also considered theoretically.
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35.
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36.
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37.
  • Miron, C, et al. (författare)
  • Mapping potential energy surfaces by core electron excitation: the resonant Auger decay spectrum of BF3
  • 2002
  • Ingår i: Chemical Physics Letters. - 0009-2614. ; 359:1-2, s. 48-54
  • Tidskriftsartikel (refereegranskat)abstract
    • High-resolution electron spectroscopy applied under resonant Auger-Raman conditions is shown to be a powerful tool for characterizing complex potential energy surfaces of core-excited states in polyatomic systems. BF3 is used as a prototype molecule: excitation of the Bls --> 2a(2)(") transition leads to an exceptional out-of-plane vibrational excitation resolved over a wide energy range (3.6 eV). The photon energy dependence of the spectra through the resonance profile is rationalized in the frame of the relative slopes of the potential energy curves along the boron out-of-plane displacement coordinate.
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38.
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39.
  • Mocellin, A, et al. (författare)
  • Experimental study of photoionization of ozone in the 12 to 21 eV region
  • 2001
  • Ingår i: JOURNAL OF CHEMICAL PHYSICS. - : AMER INST PHYSICS. - 0021-9606. ; 115:11, s. 5041-5046 Language: English
  • Tidskriftsartikel (refereegranskat)abstract
    • The total and partial ion yield of ozone using time-of-flight is presented. The measurements were done using multicoincidence between a photoelectron and a photoion (PEPICO). Comparison with the photoelectron spectrum and previous measurements using other
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40.
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41.
  • Ohrwall, G, et al. (författare)
  • Femtosecond interatomic Coulombic decay in free neon clusters: Large lifetime differences between surface and bulk
  • 2004
  • Ingår i: Physical Review Letters. - 1079-7114. ; 93:17
  • Tidskriftsartikel (refereegranskat)abstract
    • A quantitative determination of 2s vacancy lifetimes in surface and bulk atoms of free Ne clusters has been made. While for free atoms the 2s inner-valence hole has a ps lifetime, it reduces to 6+/-1 fs for cluster bulk atoms. For surface atoms, the lifetime is on average longer than 30 fs. The lifetime estimate was obtained from fits of high-resolution photoelectron spectra of Ne clusters. The shortening of the lifetime is attributed to the coordination dependent interatomic Coulombic decay, which is extremely sensitive to internuclear distances.
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42.
  • Ohrwall, G, et al. (författare)
  • Observation of elastic scattering effects on photoelectron angular distributions in free Xe clusters
  • 2003
  • Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 36:19, s. 3937-3949
  • Tidskriftsartikel (refereegranskat)abstract
    • We report an observation of substantial deviations in the photoelectron angular distribution for photoionization of atoms in free Xe clusters compared to the case of photoionization of free atoms. The cross section, however, seems not to vary between the cluster and free atoms. This observation was made in the vicinity of the Xe 4d Cooper minimum, where the atomic angular distribution is known to vary dramatically. The angular distribution of electrons emitted from atoms in the clusters is more isotropic than that of free atoms over the entire kinetic energy range studied. Furthermore, the angular distribution is more isotropic for atoms in the interior of the clusters than for atoms at the surface. We attribute this deviation to elastic scattering of the outgoing photoelectrons. We have investigated two average cluster sizes, (N) approximate to 4000 and 1000 and found no significant differences between these two cases.
  •  
43.
  • O'Shea, JN, et al. (författare)
  • X-ray photoelectron spectroscopy of low surface concentration mass-selected Ag clusters
  • 2000
  • Ingår i: JOURNAL OF CHEMICAL PHYSICS. - : AMER INST PHYSICS. - 0021-9606. ; 113:20, s. 9233-9238
  • Tidskriftsartikel (refereegranskat)abstract
    • We have developed an experimental setup for the study of small mass-selected clusters delivered by soft landing to a model oxide support. An automated deposition system to achieve accurately quantified homogeneous surfaces is described which also overcome
  •  
44.
  • Peredkov, Sergey, et al. (författare)
  • Ioniclike energy structure of neutral core-excited states in free Kr clusters
  • 2005
  • Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 72:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The development of electronic states in krypton clusters is investigated by high-resolution core-level electron spectroscopy. The energy ordering of bulk versus surface 3d(-1)np(n > 5) core-excited states in neutral clusters is demonstrated to be reversed to the 3d(-1)5p level situation. The cluster 3d(-1)6p,7p states are proven to be at a lower energy than the corresponding atomic levels. These findings reveal the ioniclike energy structure of the neutral cluster core-excited levels. The phenomenon is explained by a spatial spread of the excited orbitals over the cluster lattice.
  •  
45.
  • Piancastelli, MN, et al. (författare)
  • Bond-distance-dependent decay probability of the N 1s -> pi* core-excited state in N-2
  • 2000
  • Ingår i: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP PUBLISHING LTD. - 0953-4075. ; 33:9, s. 1819-1826
  • Tidskriftsartikel (refereegranskat)abstract
    • We report the observation of the unusually weak decay of the N 1s --> pi* core-excited N-2 molecule to the (B) over tilde (2)Sigma(u)(+) final state of N-2(+), which is only detectable in an experiment with high sensitivity. The resonant Auger spectra exh
  •  
46.
  • Rosenqvist, L, et al. (författare)
  • Femtosecond dissociation of ozone studied by the Auger Doppler effect
  • 2001
  • Ingår i: JOURNAL OF CHEMICAL PHYSICS. - : AMER INST PHYSICS. - 0021-9606. ; 115:8, s. 3614-3620 Language: English
  • Tidskriftsartikel (refereegranskat)abstract
    • A Doppler-type shift in the kinetic energy of atomic Auger electrons emitted after fast dissociation of O-3 molecules is observed. The resonant Auger spectrum from the decay of repulsive core-excited states reflects both the early molecular ozone decay an
  •  
47.
  • Salek, P, et al. (författare)
  • Dynamical suppression of atomic peaks in resonant dissociative photoemission
  • 2001
  • Ingår i: CHEMICAL PHYSICS LETTERS. - : ELSEVIER SCIENCE BV. - 0009-2614. ; 343:3-4, s. 332-338 Language: English
  • Tidskriftsartikel (refereegranskat)abstract
    • Resonant excitation to the F1s-sigma* dissociative state in hydrogen fluoride gives a photoelectron spectrum where the spectator part contains strong atomic lines but a participator part where such lines are lacking. We demonstrate that this contrasting b
  •  
48.
  • Salek, P, et al. (författare)
  • Generalized Franck-Condon principle for resonant photoemission
  • 1999
  • Ingår i: PHYSICAL REVIEW A. - : AMERICAN PHYSICAL SOC. - 1050-2947. ; 60:4, s. 2786-2791
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • A generalized Franck-Condon (GFC) principle for resonant x-ray Raman scattering and for resonant photoemission in particular is derived and numerically investigated. The GFC amplitudes differ from ordinary FC amplitudes by the presence of photon and photo
  •  
49.
  • Salek, Pawel, et al. (författare)
  • Resonant x-ray Raman scattering involving avoided crossings in the final-state potential-energy curves
  • 2000
  • Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : Elsevier BV. - 1050-2947 .- 1094-1622. ; 62:6
  • Tidskriftsartikel (refereegranskat)abstract
    • The role of avoided crossings for resonant x-ray Raman scattering is explored. The strong dependence of the electronic transition amplitudes on internuclear distance at avoided crossings causes new, and even anomalous, spectral features, and can bring about a breakdown of the generally accepted participator or spectator classification of the transitions. We report, and apply the theory on, an experimental observation of the electron decay of the N 1s-->pi* core-excited level in N-2 the B(2)Sigma (+)(u) final state with peculiar, non-Franck-Condon, vibrational intensity distributions.
  •  
50.
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