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
  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 6518-6525 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The microcanonical temperature is shown to be a useful concept in calculations of the decay of a small isolated system with well defined energy. A simpler and more transparent description is obtained than in Klots' formulation of finite-heat-bath theory, where the system is represented by a canonical ensemble. As a further illustration of the utility of the microcanonical temperature concept, we discuss a formula derived by Dunbar for the probabilities for excitation of a single oscillator in a collection of harmonic oscillators with well defined total energy. This formula expresses the excitation probabilities in terms of the temperature for a canonical ensemble with mean energy equal to the energy of the system. However, a much improved accuracy is obtained if the canonical temperature and heat capacity are replaced by their microcanonical values. We justify this replacement through a modified derivation, in which the microcanonical temperature appears as the canonical temperature of a fictitious system with level density ρ′(E), the derivative of the level density ρ(E) of the collection of oscillators. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Nuclear and Particle Science 33 (1983), S. 453-504 
    ISSN: 0163-8998
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Radioactive119mSn has been implanted with an isotope separator in single crystals of germanium, silicon, and diamond. Implantations of low doses (∼1013 atoms/cm2) at room temperature were performed as well as of higher doses at temperatures of about 400°C. The Mössbauer spectra of these sources show mainly one line. This line originates from119mSn on substitutional lattice sites as determined from channeling experiments with 2 MeV He+ ions on the same samples. The observed systematics of the isomer shifts for119Sn is explained on the basis of the average electronic configuration ns Z snp Z p characterizing chemical bonding in the host crystals. The Debye-Waller factors measured at room temperature are compared to values calculated in a high temperature approximation which accounts for impurity-host mass difference.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Conclusion Implantation of Sn at ∼550°C into SiC and post-annealing at 1120°C has been demonstrated to lead to a predominant population of the substitutional Si sites. The electronic structure of the Sn atoms in substitutional Si sites has been shown to be strongly influenced by the partial ionicity of the host material.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We have investigated the time dependence of the fragmentation of protonated amino acids stored at 22 keV in the electrostatic ring ELISA. The ions were produced in an electrospray source and after bunching in a quadrupole trap they were excited by collisions in a Ne gas. As in earlier studies of metal clusters and fullerenes produced in “hot” ion sources we find that the dissociation of metastable molecules follows approximately a 1/t decay law until a time $\tau$ after which the yield falls off much more rapidly. We interpret this reduction as a result of radiative cooling with a characteristic cooling time, $\tau_c \simeq G\tau$ , where G is the magnitude of the exponent in an Arrhenius expression for the rate of the dominant fragmentation process. The values of $\tau$ obtained from fits to the data are in the range 9-17 ms corresponding to cooling times of a few hundred milliseconds, in good accord with the expected rate of cooling by emission from IR-active vibrations. The power-law behaviour for $t 〈 \tau$ varies somewhat between the different amino acids, with powers between -0.9 and -1.1. We argue that this may be due to a competition between fragmentation channels with different Arrhenius parameters.
    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...