ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
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
    Time dependent thermal lensing measurements of V–T energy transfer from highly excited NO2 (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 4793-4804 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The time dependent thermal lensing technique has been used to measure the vibrational relaxation of NO2 (initially excited at 21 631 cm−1) by Ar, Kr, and Xe. The energy transfer analysis was carried out in terms of 〈〈ΔE〉〉, the bulk average energy transferred per collision. This quantity was found to have a very strong dependence on vibrational energy, with a marked increase at energies greater than about 10 000 cm−1, where several electronic excited states (2B2, 2B1, and 2A2) mix with the ground state (2A1). This effect may be due to large amplitude vibrational motions associated with the coupled electronic states. Even at low energies, deactivation is faster than in other triatomic systems, probably because NO2 is an open shell molecule and electronic curve crossings provide efficient pathways for vibrational deactivation. The V–T rate constant for deactivation of NO2(010) by argon is estimated to be (5.1±1.0)×10−14 cm3 s−1. Results obtained for NO@B|2–NO2 collisions gave 〈〈ΔE〉〉 values in good agreement with literature results from fluorescence quenching experiments, indicating that V–T may be more important than V–V energy transfer in the quenching process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458573
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Excitation of CO2 by energy transfer from highly vibrationally excited benzene derivatives (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 8108-8119 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The time-resolved infrared fluorescence technique has been used to study V–V and V–T/R energy transfer to carbon dioxide from highly excited benzene, benzene-d6, toluene, and toluene-d8. The highly vibrationally excited aromatics in the electronic ground state are obtained by radiationless transitions after pumping with a KrF laser at 248 nm to the S1 excited electronic level. The V–V energy transfer from the excited parent to the asymmetric stretch mode of CO2 was measured by observing the characteristic emission of CO@B|2 near 4.3 μm. From these measurements, the probability per collision of formation of CO*2 was determined as a function of the internal energy in the excited aromatic. In all cases investigated, this probability is ≤0.1% at the initial excitation energy of 40 000 cm−1 and it is approximately directly proportional to the vibrational energy of the excited aromatic. The total concentration of CO@B|2 produced as a result of the many collisions needed to totally deactivate the excited aromatic amounted to 〉5% of the initial concentration of the excited aromatic and the quantitative values obtained are in excellent agreement with other work.A simple dipole–dipole interaction model is shown to explain the observed magnitude of V–V energy transfer and it is used to predict the amount of energy transferred to the bending mode of CO2. A key feature of this model is that the states of the highly vibrationally excited polyatomic are assumed to be broadened by rapid intramolecular vibrational redistribution of energy. In addition to the V–V energy-transfer measurements, the average energy lost per collision by the excited aromatic was determined as a function of the vibrational energy of the aromatic, and the rate constants were determined for CO*2 deactivation by the nondeuterated species. For the deuterated species, the results implicated a contribution from resonant V–V transfer between the C–D stretch modes and the asymmetric stretch mode of CO2. The overall results for the CO2 collider gas indicate that V–V energy transfer contributes a relatively small portion of the total energy transfer, and that portion can be described with the dipole–dipole interactions model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461290
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Vibrational relaxation of highly excited toluene (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 176-188 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The collisional loss of vibrational energy from gas-phase toluene, pumped by a pulsed KrF laser operating at 248 nm, has been observed by monitoring the time-resolved infrared fluorescence from the C–H stretch modes near 3.3 μm. The fragmentation quantum yield of toluene pumped at 248 nm was determined experimentally to be ∼6%. Energy-transfer data were obtained for 20 collider gases, including unexcited toluene, and analyzed by an improved inversion technique that converts the fluorescence intensity to the bulk average energy, from which is extracted 〈〈ΔE〉〉, the bulk average amount of energy transferred per collision. Comparisons are presented of these results with similar studies of benzene and azulene, and with the time-resolved ultraviolet absorption study of toluene carried out by Hippler et al. [J. Chem. Phys. 78, 6709 (1983)]. The present results show 〈〈ΔE〉〉 to be nearly directly proportional to the vibrational energy of the excited toluene from 5000 to 25 000 cm−1. For many of the colliders at higher energies, the energy dependence of 〈〈ΔE〉〉 is somewhat reduced. A simple method is described for obtaining good estimates of 〈ΔE〉d (the energy transferred per collision in deactivating collisions) by carrying out an appropriate least-squares analysis of the 〈〈ΔE〉〉 data. The values of 〈ΔE〉d are then used in master-equation calculations to investigate possible contributions from "supercollisions'' (in which surprisingly large amounts of energy are transferred) in the deactivation of toluene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461473
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Collisional deactivation of highly vibrationally excited benzene pumped at 248 nm (1990)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 94 (1990), S. 6341-6350 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100379a036
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Emission from ozone excited electronic states (1990)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 94 (1990), S. 8390-8393 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100385a004
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Radiative recombination in the electronic ground state (1992)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 96 (1992), S. 7361-7367 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100197a042
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Isotope effects in the vibrational deactivation of large molecules (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 1809-1817 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Collisional deactivation of highly vibrationally excited gas phase toluene-d8 and benzene-d6 pumped at 248 nm, has been investigated by monitoring the time resolved infrared fluorescence from the C–D stretch modes near 4.3 μm. For toluene-d8, energy transfer data were obtained for about 20 collider gases, including unexcited toluene-d8; for benzene-d6, only a few colliders were investigated. For both systems the data were analyzed by an inversion technique that converts the fluorescence decay to the bulk average energy, from which is calculated the average energy transferred per collision, 〈〈ΔE〉〉inv. Data obtained earlier for benzene-d0 were reanalyzed and the revised results are reported. Results for both normal and deuterated excited species show 〈〈ΔE〉〉inv to be nearly directly proportional to the vibrational energy 〈〈E〉〉inv of the excited molecule from 5 000 to 25 000 cm−1. However, for pure toluene-d8, benzene-d6, and a few other collider gases at high energies, the slope of the 〈〈ΔE〉〉inv vs 〈〈E〉〉inv curve is reduced and even becomes negative at sufficiently high energies. The results obtained for normal and deuterium-containing species are discussed in terms of possible quantum effects and mechanisms for energy transfer. In particular, it is considered likely that V–T/R energy transfer dominates over V–V, and the lowest frequency vibrational modes are the conduits for the energy transfer, in agreement with results for small molecules. Attention is called to a fundamental difference between classical and quantum statistics and how this difference may adversely affect classical trajectory simulations of large molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463168
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Kinetic studies of the deactivation of O2(1Σg+) and O(1D) (1990)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 1283-1301 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the deactivation of O2(1Σg+) is studied in real time. O2(1Σg+) is generated in this system by the O(1D) + O2 reaction following O3laser flash photolysis in the presence of excess O2, and it is monitored by its characteristic emission band at 762 nm. Quenching rate constants were obtained for O2, O3, N2, CO2, H2O, CF4and the rare gases. Since O(1D) is the precursor for the formation of O2(1Σg+), the addition of an O(1D) quencher effectively lowers the initial concentration of O2(1Σg+). By measuring the initial intensity of the 762 nm fluorescence signal, the relative quenching efficiencies were determined for O(1D) quenching by N2, CO2, Xe, and Kr with respect to O2; the results are in good agreement with literature values.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550221207
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Incubation in cyclohexene decomposition at high temperatures (1990)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 187-206 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed master equation simulation has been carried out for the thermal unimolecular decomposition of C6H10 in a shock tube. At the highest temperatures studied experimentally [J. H. Kiefer and J. N. Shah, J. Phys. Chem., 91, 3024 (1987)], the average thermal vibrational energy is greater than the reaction threshold and therefore 〈ΔE〉 (up and down steps) is positive for molecules at that energy, rather than negative; the converse is true at lower temperatures. The calculated incubation time, in which the decomposition rate constant rises to 1/e of its steady state value, is found to be only weakly dependent on temperature (at constant pressure) between 1500 K and 2000 K and to depend almost exclusively on 〈ΔE〉d (down steps, only), and not on collision probability model. Simulations of the experimental data show the magnitude of 〈ΔE〉d depends weakly on assumed collision probability model, but is nearly independent of temperature. The second moment 〈ΔE〉½ is found to be independent of both temperature and transition probability model. The experimental data are not very sensitive to the possible energy-dependence of 〈ΔE〉d for a wide range of assumptions. It is concluded that the observed experimental “delay times” probably can be identified with the incubation time; further experiments are desirable to test this possibility and obtain more direct measures of the incubation time.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550220207
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    facet.materialart.
    Unknown
    Isotope effects in the vibrational deactivation of large molecules (1992)
    American Institute of Physics
    Details
    Publication Date: 1992-08-01
    Print ISSN: 0021-9606
    Electronic ISSN: 1089-7690
    Topics: Chemistry and Pharmacology , Physics
    Published by American Institute of Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...