GLORIA

GEOMAR Library Ocean Research Information Access

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 102 (1995), S. 4027-4036 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The connection between dephasing of optical coherence and the measured spectral density of the pure solvent is made through measurements and calculations of photon echo signals. 2-pulse photon echo measurements of a cyanine dye in polar solvents are presented. Signals are recorded for both phase matched directions enabling accurate determination of the echo signal time shift. Echo signals are calculated by two approaches that employ the response function description of nonlinear spectroscopy; (i) a single Brownian oscillator line shape model, and (ii) the line shape obtained using the solvent spectral density. The strongly overdamped Brownian oscillator model incorporates only a single adjustable parameter while the experimental data present two fitting constraints. The second model incorporates the measured solvent spectral density. Both give very good agreement with the experimental results. The significance of the second method lies in this being a new approach to calculate nonlinear spectroscopic signals, for comparison with experimental data, that uses directly the measured spectrum of equilibrium fluctuations of the solvent. This approach also provides a better conceptual perspective for deriving insight into the nature of the solute–solvent coupling mechanism. Comparing the parameters for the strength of interaction in a variety of polar solvents it is found that the coupling involves the solvent polarizability and not the solvent polarity. The interaction mechanism cannot be deduced from the Brownian oscillator calculations. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation 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 101 (1994), S. 7566-7579 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The viscosity dependence of the photoisomerization of trans-stilbene in compressed liquid ethanol shows deviations from a simple power law description in the viscosity range from 1 to 4 mPa s. Corresponding deviations are observed in the solvents methanol, n-propanol, and n-butanol. This behavior is attributed to a competition between solvent relaxation and barrier crossing in the S1 state of trans-stilbene. The relative time scales of barrier crossing and solvent relaxation change as the pressure increases, because the dielectric relaxation rate of the solvent decreases more rapidly with increasing viscosity than the barrier crossing rate. Consequently, the reaction takes place in an increasingly retarded solvent environment which no longer relaxes completely around the changing charge distribution of the solute along its reaction path, giving rise to "dielectric friction.'' In contrast to trans-stilbene, the corresponding reaction of diphenylbutadiene in n-alkanols shows a much weaker sensitivity to solute-solvent interaction and, consequently, a simple inverse viscosity dependence of the photoisomerization rate is observed in all alkanols such as described by the Kramers–Smoluchowski theory. This significant difference is probably caused by smaller sudden polarization effects along the reaction path in diphenylbutadiene. The observed dependence of the trans-stilbene barrier crossing rate on pressure is compared either to a model with density dependent effective barrier height, or to a simple continuum model of the frequency dependence of the dielectric friction in the limit of weak coupling. Neither model works well unless a very strong viscosity dependence of the dielectric relaxation time of the solvent (τD∝η10) is employed to obtain agreement with the observed viscosity dependence of the barrier crossing rate.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 71 (2000), S. 411-417 
    ISSN: 1432-0649
    Keywords: PACS: 78.47+p; 82.40.Js; 82.50.Fv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Polarization-resolved femtosecond experiments are shown to yield valuable insight into transition-state dynamics associated with ultra-fast photodissociation reactions of triatomic species in liquid solution. After the fundamental act of bond fission is completed, such experiments reveal rotational dynamics of the fragments, which can be used to extract information regarding fragment rotational excitation in the asymptotic limit of the reaction.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 26 (1995), S. 535-551 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The results of degenerate wavenumber third-order polarization (pump-probe) measurements of vibrational dephasing and relaxation in a variety of solvents are reported. The 20 fs duration pulses are sufficiently short to allow the preparation and detection of vibrational coherences (i.e. wavepackets) to 800 cm-1 oscillator wavenumber. The high quality of the pump-probe data permits the unique determination of eight underdamped modes for the cyanine dye under study. The relaxation of the underdamped modes does not show a significant solvent dependence. The relaxation mechanisms that give rise to loss of vibrational coherence and to the solvent-dependent relaxation of low-wavenumber (〈100 cm-1) modes are discussed. The wavenumber dependence of the vibrational dephasing rate varies with a scaled exponential dependence exp(  - ω/ω0), or equally well with the inverse square of the vibrational wavenumber. The exponential form would imply that vibrational dephasing occurs by population relaxation. The latter form, however, may imply higher order coupling between the bath and solute through the solute vibrational anharmonicity such that the off-diagonal contributions to the prepared wavepacket relax by pure dephasing. Exponentially decaying contributions to the pump - probe signal are found to arise from overdamped modes that are excited by the short laser pulses as opposed to a solvation response. The solvent-dependent relaxation of these overdamped modes is determined to be similar to diffusive unimolecular barrier crossing dynamics observed in dense media.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2012-11-08
    Description: High activity of sorafenib in FLT3-ITD-positive acute myeloid leukemia synergizes with allo-immune effects to induce sustained responses Leukemia 26, 2353 (November 2012). doi:10.1038/leu.2012.105 Authors: S K Metzelder, T Schroeder, A Finck, S Scholl, M Fey, K Götze, Y C Linn, M Kröger, A Reiter, H R Salih, T Heinicke, R Stuhlmann, L Müller, A Giagounidis, R G Meyer, W Brugger, M Vöhringer, P Dreger, M Mori, N Basara, K Schäfer-Eckart, B Schultheis, C Baldus, A Neubauer & A Burchert
    Keywords: AMLsorafenibFLT3-ITDstem cell transplantation
    Print ISSN: 0887-6924
    Electronic ISSN: 1476-5551
    Topics: Medicine
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...