Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989  (12)
Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 3240-3245 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Kr clusters produced in a supersonic nozzle expansion have been studied by electron impact ionization mass spectrometry. Mass resolved spectra (with n up to 180) show two homologous series consisting of Kr+n and Kr2+n ions. The distribution of Kr+n ions shows distinct magic number effects, the observed abundance anomalies being very similar to the ones observed in Ar and Xe. This confirms the superior stability of closed-shell and -subshell icosahedral structures. Moreover, we have found evidence for the occurrence of Kr3+n and Kr4+n ions. It was possible to determine appearance sizes of these multiply charged cluster ions (yielding n2=69, n3=156, and n4=264), and to study the electron energy dependence of singly and doubly charged cluster ions (yielding a linear threshold law). These results are discussed in view of various theoretical considerations and previous results where available.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 295-301 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Metastable decay of Ar+@B|3 produced by electron impact ionization of a supersonic Ar cluster beam has been investigated qualitatively and quantitatively with a double focusing sector field mass spectrometer. We present direct experimental proof that the observed metastable decay of Ar+*3 into Ar+ in the microsecond time regime proceeds predominantly via a sequential decay series Ar+@B|3→k3,2Ar+*2→ k2,1Ar+ involving the evaporation of a single monomer in each of these successive decays. The metastable decay rates deduced are very different, i.e., k3,2 =45 s−1 and k2,1 =680 s−1 at an ion acceleration voltage of 3 kV. Moreover, the metastable decay rates of Ar+@B|3 exhibit a strong dependence on time elapsed since electron impact production of the Ar+3, and on ion production parameters (i.e., size and internal excitation energy of the neutral precursor). For instance photodissociation (with visible laser light) of the neutral cluster beam leads to a dramatic increase of the observed metastable reaction rules yielding values of up to 100 000 3−1 in the μs time regime.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 4289-4293 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Clusters of N2 molecules formed in a supersonic nozzle expansion have been studied by electron impact ionization mass spectrometry. Mass resolved spectra (with n up to 190) show three homologous series, i.e., consisting of (N2)+n, (N2)nN+, and [(N2)n N]2+ ions. The distribution of (N2)+n ions shows distinct magic number effects. Moreover, there is evidence for the existence of (N2)2+n and (N2)3+n ions. The critical appearance sizes of observed multiply charged cluster ions are (N2)2+99, (N2)99N2+, and (N2)3+215. These results are compared with theoretical predictions. Moreover, a study of the electron energy dependence of singly and doubly charged N2 cluster ions close to threshold (appearance energies) gives new insight into the ionization mechanism.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 1288-1289 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report the first well resolved SO2 cluster ion spectrum showing doubly charged parent and fragment ions. The critical appearance size deduced for doubly charged SO2 clusters is n2=21 and for triply charged SO2 clusters n3=49. This result is compared with theoretical predictions.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 6884-6888 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Electron attachment and electron impact ionization of SF6 and SF6/Ar clusters have been investigated in a molecular beam/electron impact ion source/mass spectrometer system. Positive ion mass spectra of neat SF6 clusters contain [(SF6)n⋅SFx]+ fragment ion series with 0≤x≤5 and in addition [(SF6)nS2F5]+ ions which have to be formed via international ion molecule reactions. Positive ion mass spectra of mixed SF6/Ar clusters include ion series of nonstoichiometric fragment ions (SF5⋅Arn)+, (SF6⋅SF5⋅Arn)+, [(SF6)2⋅SF5⋅Arn]+, and, in addition, stoichiometric ions comprised of (SF6⋅Arn)+ and [(SF6)2Arn]+. These stoichiometric ions are only present with n≥3. Electron attachment to neat SF6 clusters gives rise only to stoichiometric (SF6)−n ions, whereas attachment to mixed SF6/Ar clusters yields ion series consisting of (ArnSF6)−, [Arn(SF6)2]−, and [Arn⋅(SF6)3]−. This indicates that the dissociative channel into SF−5 present in the monomer is efficiently quenched in case of clusters. The negative ion mass spectra show in contrast to the positive ion mass spectra a strong dependence on electron energy due to a strong resonance of the attachment cross sections near zero electron energy.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 4091-4094 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In previous experiments on doubly charged Xe clusters, no Xe2+n cluster ions were observed for n less than 53 atoms and no Xe3+n for n less than 114 atoms. From recent computer simulations it was inferred that Xe2+51 ions have lifetimes ∼100 ps while Xe2+55 ions have lifetimes ∼10 μs in agreement with these previous experimental results. Using a high performance mass spectrometer we have repeated these experiments. In contrast to these earlier findings, we are here able to observe doubly charged Xe cluster ions with sizes down to n2=47 (at lifetimes of ∼400 μs). The critical appearance size for triply charged Xe clusters is n3=108. In accordance with a recently suggested sequential ionization mechanism for the production of stable doubly charged van der Waals cluster ions, the appearance energy of Xe2+n was found to lie well below the appearance energy of Xe2+ from Xe.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 2942-2946 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Electron attachment to CO2 clusters formed by nozzle expansion was investigated in a crossed molecular-beam–electron-impact–mass spectrometer system. In addition to cluster ions previously observed at 3–4 eV electron energy we observe presently cluster ions produced at around zero electron energy. Some of these ions are likely produced by a less dissociative production mechanism allowing the probing of cluster beams with better reliability than previously.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Recently we have observed [1–4] photodissociation of neutral van der Waals clusters induced by visible laser light using coaxial interaction between the beams. Because of possible artifacts we have repeated here this experiment in a crossed beam configuration. The present results confirm the occurrence of this photodissociation effect. We suggest tentatively that excitation via Raman scattering is the origin of this phenomenon.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1434-6079
    Keywords: 36.40 ; 07.75
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Clusters of Ar, Kr, Xe, N2, O2, CO2, SO2 and NH3 formed by supersonic nozzle expansion have been studied by electron impact ionization mass spectrometry (up to 15000 amu). Besides mass spectra of singly charged ions showing the characteristic anomalous distributions, we have in particular investigated the properties of multiply charged cluster ions. Critical appearance sizes of doubly and triply charged cluster ions, n2 and n3 respectively, found in the present study confirm recent theoretical predictions about n3/n2 and their dependence on the properties of the cluster constituents. The appearance energies of multiply charged cluster ions determined are shifted way below the appearance energies of the respective monomer ions. These huge red shifts together with the observed linear threshold laws and large maximum ionization efficiencies indicate that multiply charged cluster ions are produced by sequential single ionization events of one incoming electron at different cluster sites. Furthermore, we have also obtained for the first time clear evidence that (for electron energies above the appearance energy of doubly charged ions) an appreciable amount of singly charged (also fragment) ions is produced via Coulomb explosion of unstable doubly charged ions in the ion source.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 12 (1989), S. 303-305 
    ISSN: 1434-6079
    Keywords: 36.40 ; 34.80.G
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electron attachment and electron impact ionization of SF6 clusters have been investigated quantitatively in a molecular beam/electron ion source/mass spectrometer system as a function of electron energy E (0≤E≤180 eV) and as a function of cluster size.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...