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  • 1
    Electronic Resource
    Electronic Resource
    Photoionization spectroscopy of small mercury clusters in the energy range from vacuum ultraviolet to soft x ray (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 680-689 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have measured the single and double photoionization efficiency of Hgn mass selected clusters as a function of photon energy between 30 and 110 eV for masses ranging from n=1 to 36 for the singly ionized and from n=5 to 70 for the doubly ionized clusters, using the light beam issued from a wiggler at the BESSY synchrotron. The results show in all cases a spectrum similar to the 5d→εf shape resonance previously observed in the isolated atom. In contrast, the expected 5p→6p transition allowed by hybridization of the 6s and 6p orbitals is not observed. We also compared the mass spectra of singly and doubly charged mercury clusters ionized by electron impact (30–90 eV) to those of clusters ionized by synchrotron radiation (30–70 eV). We found that the ratio Hg2+n/Hg+n was higher for photoionization at low energy and for electron impact ionization at high energy. Finally, we estimated the critical stability size of the triply charged clusters. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469180
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  • 2
    Electronic Resource
    Electronic Resource
    Homogeneous nucleation rates of supercooled water measured in single levitated microdroplets (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 6521-6527 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Homogeneous nucleation rates are determined for micrometer sized water droplets levitated inside an electrodynamic Paul-trap. The size of a single droplet is continuously measured by analyzing the angle-resolved light scattering pattern of the droplets with classical Mie theory. The freezing process is detected by a pronounced increase in the depolarization of the scattered light. By statistical analysis of the freezing process of some thousand individual droplets, we obtained the homogeneous nucleation rate of water between 236 and 237 K. The values are in agreement with former expansion cloud chamber measurements but could be determined with considerably higher precision. The measurements are discussed in the light of classical nucleation theory in order to obtain the size and the formation energy of the critical nucleus. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479946
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  • 3
    Electronic Resource
    Electronic Resource
    Photoionization and fragmentation of alkali metal clusters in supersonic molecular beams (1982)
    Springer
    Applied physics 29 (1982), S. 55-61 
    Details
    ISSN: 1432-0649
    Keywords: 36 ; 07.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A supersonic molecular beam, pulsed laser and time-of-flight mass spectrometer are arranged together in order to study photo- and auto-ionization, two-photon-ionization and fragmentation processes of alkali clusters as a function of the laser wavelength. In spite of an unfavourable duty cycle, however, the apparatus reaches a considerably higher sensitivity than cw experiments. Alkali clustersM n (n≲21) have been observed and investigated. The well resolved TOF mass spectra are commonly accompanied by significant and broad signals of metastable ions, a phenomenon which cannot be observed by quadrupole mass spectrometry. ParticlesM n (n≲4) have been investigated by twophoton ionization using two different laser wavelengths. Several new electronic transitions for Na3 are found; commonly, however, the excitation and ionization channels are accompanied by strong fragmentation processes. The fragment patterns are very sensitively dependent upon the laser wavelength even when working near the ionization threshold. The results are a strong indication, that the peak intensities of cluster mass spectra cannot easily be related to the intensity distribution of the neutral cluster beam.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694369
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  • 4
    Electronic Resource
    Electronic Resource
    Cluster–surface interaction studied by time-resolved two-photon photoemission (1999)
    Springer
    Applied physics 68 (1999), S. 453-457 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 36.40.sx; 61.46.+w; 79.60.-i; 78.47.+p
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: n + clusters (n=2-9)deposited onto highly oriented pyrolytic graphite (HOPG) substrates at liquid nitrogen temperatures. The deposition was carried out with variable kinetic energies of the clusters. Clusters deposited with high kinetic energy (up to 60 eV/cluster) become fragmented upon impact. For low deposition energies (1–4 eV/cluster) the size dependence of the photoelectron spectra reveals a pronounced odd/even effect, which is well known for gas phase silver clusters. This indicates that the soft deposited clusters retain their size and identity on the sample. The phase of the odd/even effect suggests that transient negatively charged cluster ions serve as an intermediate step in the two-photon photoemission process. The lifetime of the anions rises with cluster size. This is attributed to an increasing electronic density of states for larger clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400050648
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  • 5
    Electronic Resource
    Electronic Resource
    CVL-pumped dye laser for spectroscopic application (1984)
    Springer
    Applied physics 35 (1984), S. 31-36 
    Details
    ISSN: 1432-0649
    Keywords: 42.60 ; 33 ; 36
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A spectroscopic dye laser system-pumped by a Copper Vapor Laser (CVL)-has been built and optimized for different dye solutions operating in the spectral range from 530 to 890 nm. Conversion efficiencies up to 40% were reached in broad band operation, 24% with a prism expander grating cavity, and 20% in grazing incidence configuration, which operated at typical band widths of 3 GHz. Second harmonic generation (SHG) of the dye laser output produced tunable uv-radiation between 260 and 408 nm at conversion efficiencies ≦5%. Fundamental and SHG output were used for resonant ionization experiments in molecular beams.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697518
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  • 6
    Electronic Resource
    Electronic Resource
    Temporal coherent control induced by wave packet interferences in one and two photon atomic transitions (1998)
    Springer
    The European physical journal 2 (1998), S. 131-141 
    Details
    ISSN: 1434-6079
    Keywords: PACS. 32.80.Qk Coherent control of atomic interactions with photons - 32.80.Rm Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The interaction of a sequence of two identical ultrashort laser pulses with an atomic system results in quantum interferences as in Ramsey fringes experiments. These interferences allow achievement of temporal coherent control of the excitation probability. We present the results of a temporal coherent control experiment on two different atomic systems: one-photon absorption in K (4s-4p) and two-photon absorption in Cs (6s-7d). In K, the quantum interferences between the two excitation paths associated with the laser pulses are revealed through rapid oscillations of the excitation probability as a function of the time delay between the two pulses. These oscillations take place at the transition frequency (period T = 2.56 fs). The interferences are modulated by beats (at about 580 fs) resulting from the doublet structure of the excited state (4p (2 P 1/2 , 2 P 3/2 )). Three complementary interpretations of this experiment are presented: in terms of beats of quantum interferences, of variation in the spectrum intensity, and of wave packet interferences. Whenever the two laser pulses are temporally overlapped, optical interferences are superimposed on to the quantum interferences. The distinction between these two types of interference is clearly revealed in the two-photon excitation scheme performed on Cs (6s-7d (2 D 3/2 , 2 D 5/2 )) because quantum interferences occur at twice the frequency of the optical interferences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100530050122
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  • 7
    Electronic Resource
    Electronic Resource
    Laser applications for atmospheric pollution monitoring (1998)
    Springer
    The European physical journal 4 (1998), S. 231-238 
    Details
    ISSN: 1434-6079
    Keywords: PACS. 42.68.-w Atmospheric optics - 42.62.Fi Laser spectroscopy - 92.60.Sz Air quality and air pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: In this paper, we present an overview of the capabilities of linear and non-linear spectroscopy for the 3D-analysis of gaseous pollutants and aerosols in the atmosphere. The basic technique is Lidar (Light Detection and Ranging). Results obtained in Sevilla and Lyon about the ozone smog formation and the dynamics of the transport of dust particles are presented. Finally, non-linear Mie scattering on atmospheric aerosols has been demonstrated in the laboratory, opening new perspectives for remote sensing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100530050204
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  • 8
    Electronic Resource
    Electronic Resource
    Two photon photoemission of deposited silver clusters (1999)
    Springer
    The European physical journal 9 (1999), S. 523-527 
    Details
    ISSN: 1434-6079
    Keywords: PACS: 36.40.Sx Diffusion and dynamics of clusters – 61.46.+w Clusters, nanoparticles, and nanocrystaline materials – 79.60.-i Photoemission and photoelectron spectra – 78.47.+p Time-resolved optical spectroscopies and other ultrafast optical measurement in condensed matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We use time resolved two photon photoemission to study the stability of size selected silver clusters deposited onto highly oriented pyrolytic graphite (HOPG) substrates. Size-selected Ag n + clusters (n=2-9) are deposited at low coverage onto HOPG surfaces at liquid nitrogen temperatures. After deposition, the samples are irradiated by a series of ultrashort laser pulse pairs. Photoelectrons created by two photon photoemission are collected in a magnetic bottle type time-of-flight photoelectron spectrometer. Their kinetic energy distribution is recorded as a function of the delay time between subsequent light pulses. With the exception of Ag3 the size dependence of the photoelectron spectra reveals a pronounced odd/even effect, which is well known for gas phase silver clusters. This indicates that the deposited clusters retain their size and identity on the sample. The lifetime of the photoexcitation rises with cluster size. This is attributed to an increasing electronic density of states for larger clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100530050492
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  • 9
    Electronic Resource
    Electronic Resource
    Optische Massenspektrometrie kleinster Metallaggregate mittels 2-Photonen-Ionisation (1983)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 314 (1983), S. 326-331 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Methode der 2-Photonen-Ionisierung wurde erfolgreich an Alkali-Aggregaten zur massenselektiven optischen Spektroskopie eingesetzt. Die dabei erzielte Nachweiswahrscheinlichkeit ist konventionellen Ionisierungsmethoden weit überlegen. Die Spektren ermöglichen Aussagen über Geometrie und Temperatur der untersuchten Partikel. Die Methode erscheint daher sehr geeignet, zerstäubte Neutralteilchen zu analysieren.
    Notes: Summary The method of 2-photon-ionisation has successfully been applied to alcali aggregates for a mass selective spectroscopy. The detection efficiency obtained is by far superior to conventional ionisation methods. The spectra allow conclusions about the geometry and temperature of the investigated particles. Therefore the method seems to be well suited for analyzing sputtered neutral particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00516832
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  • 10
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    Spectroscopy of Size-Selected Neutral Clusters: Femtosecond Evolution of Neutral Silver Trimers (1995)
    American Physical Society
    Details
    Publication Date: 1995-05-22
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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