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Dynamics in condensed molecular systems studied by incoherent light (1996)

Kummrow, A. ; Lau, A.

Springer

Applied physics 63 (1996), S. 209-223

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ISSN: 1432-0649

Keywords: 42.65.Dr ; 78.47. + p ; 42.50.Md ; 33.70.Jg

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract Applications of incoherent light techniques to time-resolved studies in condensed matter are reviewed. Vibrational dephasing ofβ-carotene and a heptamethine dye was studied by interferometric coherent anti-Stokes Raman scattering in solution revealing dephasing times between 300 fs and 1.1 ps. This technique gives results that are analogos to spectral methods, but vibrational frequencies can be determined more precisely. Electronic dephasing was studied for a variety of dyes. Forced light scattering is used to measure the initial evolution of the lineshape functiong(t) up to about 50 fs. In the lowest order approximation,g(t) =Δ 2 t 2 /2,, the dephasing is characterized by a modulation strengthΔ = 25 to 150 THz depending on the dye, the solvent and its temperature, and the pump laser wavelength. Interestingly, the modulation decreases for heptamethine in the long-wavelength tail of the absorption band. Brillouin scattering gives rise to finite dephasing times of neat solvents in forced light scattering.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01833789

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Resonance Raman studies of heterocyclic aromatic compounds showing ultrafast intramolecular proton transferThis paper is dedicated to Professor D. A. Long on the occasion of his 70th birthday. (1995)

Pfeiffer, M. ; Lenz, K. ; Lau, A. ; [et al.]

Chichester [u.a.] : Wiley-Blackwell

Journal of Raman Spectroscopy 26 (1995), S. 607-615

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ISSN: 0377-0486

Keywords: Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Notes: Resonance Raman spectra of the three isoelectronic proton transfer systems 2-(2′-hydroxy-5′-methylphenyl)-benzotriazole (TIN), 2-(2′-hydroxyphenyl)benzothiazole (HBT) and 2-(2′-hydroxyphenyl)benzoxazole (HBO) were measured with excitation in the range of the S0-S1 absorption band of the enol tautomers. In each compound, about 15 modes in the wavenumber range between 120 and 1650 cm-1 show a strong coupling to the electronic transition. In TIN and HBT, combination tones of the strongest mode below 500 cm-1 and the vibrations at higher wavenumbers point to the strong anharmonicity of the low wavenumber motion. The experimental results are analysed by normal-mode calculations, which provide insight into the microscopic elongations in the molecules. The coupling strengths derived from the spectra are used to calculate the envelope of the S0-S1 absorption bands of TIN and HBT, reproducing the measured spectra very well. Theoretical simulations of the combination tone spectra give information on the vibrational modes involved in excited-state proton transfer.

Additional Material: 8 Ill.