Library

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
Filter
  • 2000-2004  (3)
Source
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    9,9′-Bianthryl and its van der Waals complexes studied by rotational coherence spectroscopy: Structure and excited state dynamics (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 11109-11126 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The structure and excited state dynamics of jet-cooled 9,9′-bianthryl (BA) and its 1:1 van der Waals (vdW) complexes with Ne, Ar, and H2O were studied using rotational coherence spectroscopy (RCS). For a free BA molecule, the magnitude and persistence of the recurrent transient appearing in the time-correlated single photon counting (TCSPC) measurement was found to be dependent on the torsional level of BA, indicating the rotational constant changes with the torsional energy level. The RCS–TCSPC measurement of the BA–Ar and BA–H2O complexes in the S1 state showed no coherent transients. However, the pump–probe time-resolved fluorescence depletion (TRFD) detected the weak J-type transient. Those facts imply the loss of coherence in the BA vdW complexes due to the excited-state dynamics, which coincides with the analysis of the laser-induced fluorescence excitation and dispersed fluorescence spectra. The structure of the ground-state 1:1 BA complex with Ne, Ar, and H2O was determined based on the RCS transients observed in the TRFD measurement with the help of a minimum energy structure calculation using atom–atom pairwise potentials. The rapid dephasing in the excited state was demonstrated by the magic angle TRFD detection near t=0. The dominant dephasing process for the rare-gas complexes is ascribed to intramolecular vibrational energy redistribution (IVR) which is accelerated by significant coupling between the torsional vibration and the low-lying vdW vibrations. IVR process for the H2O complex accompanies the rapid conversion to the charge-transfer state, which is also responsible for the loss of excited-state coherence. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1288518
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Stereodynamics of the reactions of O(3P) with saturated hydrocarbons: The dependences on the collision energy and the structural features of hydrocarbons (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 8338-8346 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: State-selected differential cross sections (DCSs) have been measured for the OH radicals produced from the reactions of O(3P) with saturated hydrocarbons by utilizing Doppler-resolved polarization spectroscopy. Stereodynamics in the reactions of secondary (c-C6H12) and tertiary (i-C4H10) hydrogen atoms are discussed based on the dependences of the DCSs on the collision energy and the structure of these hydrocarbons. For the c-C6H12 reaction, the DCS of the OH(2Π3/2,v′=1,j′=3.5,A′) shows predominant intensities in the backward hemisphere with reference to the incident O(3P) atom at a mean collision energy of 〈Ecoll〉=12 kJ/mol. When the collision energy is raised to 〈Ecoll〉=33 kJ/mol, the OH radicals scattered in the forward hemisphere grow almost to match those in the backward hemisphere. The observed increase in the forward scattering implies that the collision energy makes the large impact parameter collisions contribute to the reactive scattering. At a similar collision energy of 〈Ecoll〉=31 kJ/mol the forward scattering component in the DCS of the i-C4H10 reaction does not exceed that of the c-C6H12. This shows that the cone of acceptance is not enlarged in the i-C4H10 reaction from that in the c-C6H12 reaction, as opposed to the expectation based on the height of activation barrier. The absence of the enlargement of the cone of acceptance can be attributed to a large steric hindrance caused by the three bulky methyl groups surrounding the reactive tertiary C–H bond of i-C4H10. The difference in the steric hindrance can explain the difference in the temperature-dependent pre-exponential factors of the macroscopic reaction rates between the abstraction of the secondary and tertiary C–H bonds. The collision energy dependence of the DCS as well as the internal excitation of alkyl radical products reveal that the O(3P)+alkane reactions are not always dominated by the simple rebound mechanism, which has long been believed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481440
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    A high-temperature high-pressure optical cell for general-purpose spectrometers designed for supercritical water experiments (2001)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 3605-3609 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a compact size high-temperature high-pressure optical cell that can be mounted on a commercially available general-purpose spectrometer. A small electric furnace heats the high-pressure optical cell while a water-cooled thermal shielding jacket protects the spectrometer. This cooling device works quite effectively to eliminate undesirable heating of spectrometer optics and thus makes it possible to take spectra at temperatures up to 600 °C with an ordinary spectrometer. The optical cell is made of Hastelloy-X and equipped with two optical windows of synthetic sapphire. The length and the diameter of the optical path are 10 and 6 mm, respectively. As the optical cell is combined with a flow system, which allows the quick replacement of the sample solution with the reference water, the reference signal can be taken immediately after the measurement of the sample signal. The developed cell can be operated up to 60 MPa and 600 °C without any special modification to the spectrometer. The NiBr2 absorption spectra were taken under the supercritical water condition to demonstrate the efficiency of the optical cell. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1389494
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...