Resonance Raman and femtosecond absorption studies of vibrational relaxation initiated by ultrafast intramolecular proton transfer

Lenz, K.; Pfeiffer, M.; Lau, A.; Elsaesser, Thomas

doi:10.1016/0009-2614(94)01069-2

Cited by 63 publications

(43 citation statements)

References 13 publications

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“…It was proposed from this kind of experiments that IVR is not necessarily ultrafast, even for large molecules like stilbene 11,12 or 2-͑2'-hydroxy-5'-methylphenyl͒ benzotriazole. 13 However, the interesting questions concerning the initial energy distribution and the detailed pathway to a thermal distribution are not easily answered by these kinds of experiments, since usually the vibronic structures of the electronic transition are not spectrally resolved for solutions.…”

Section: Intramolecular Vibrational Energy Redistribution and Intermomentioning

confidence: 99%

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin

Mizutani

Uesugi

Kitagawa

1999

The Journal of Chemical Physics

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The formation of a vibrationally excited photoproduct of nickel octaethylporphyrin (NiOEP) upon (π, π*) excitation and its subsequent vibrational energy relaxation were monitored by picosecond time-resolved resonance Raman spectroscopy. Stokes Raman bands due to the photoproduct instantaneously appeared upon the photoexcitation. Their intensities decayed with a time constant of ∼300 ps, which indicates electronic relaxation from the (d, d) excited state (B1g) to the ground state (A1g), being consistent with the results of transient absorption measurements by Holten and co-workers [D. Kim, C. Kirmaier, and D. Holten, Chem. Phys. 75, 305 (1983); J. Rodriguez and D. Holten, J. Chem. Phys. 91, 3525 (1989)]. The Raman frequencies of NiOEP in the (d, d) excited state are shifted to lower frequencies compared to those of the ground state species, and it is reasonably interpreted by the core size expansion of the macrocycle by 0.05 Å upon the electron promotion from the dz2 to the dx2−y2 orbital. Anti-Stokes ν4 intensity in the vibrationally excited (d, d) state of NiOEP appeared promptly and decayed with time constants of 11±2 and 330±40 ps. The former is ascribed to vibrational relaxation, while the latter corresponds to the electronic relaxation from the (d, d) excited state to the electronic ground state. In contrast, the rise of anti-Stokes ν7 intensity was not instantaneous, but delayed by 2.6±0.5 ps, which indicates that intramolecular vibrational energy redistribution has not been completed in subpicosecond time regime. The peak position of the ν4 band shifted by nearly 5 cm−1 between 0 and 50 ps. The time constant for the shift of the ν4 band was 9.2±1.3 ps, which was close to that for the fast component of intensity decay of anti-Stokes bands. The ν4 band became narrower and symmetric as the delay time increases. These can be ascribed to intramolecular anharmonic coupling of the ν4 mode with the low frequency modes. The intra- and intermolecular vibrational energy relaxation in the metal excited state will be discussed.

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Section: Intramolecular Vibrational Energy Redistribution and Intermomentioning

confidence: 99%

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin

Mizutani

Uesugi

Kitagawa

1999

The Journal of Chemical Physics

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] An improved knowledge of relevant photophysical processes may result in additional discoveries, leading to the availability of more efficient laser dyes covering the entire spectral range.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Vibrational and Thermal Relaxation of Dye Molecules in Solutions

et al. 2003

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Intra-and intermolecular relaxations of dye molecules are studied after the excitation to the high-lying excited states by a femtosecond laser pulse, using femtosecond time-resolved stimulated emission pumping fluorescence depletion spectroscopy (FS TR SEP FD). The biexponential decays indicate a rapid intramolecular vibrational redistribution (IVR) depopulation followed by a slower process, which was contributed by the energy transfer to the solvents and the solvation of the excited solutes. The time constants of IVR in both oxazine 750 and rhodamine 700 are at the 290-360 fs range, which are insensitive to the characters of solvents. The solvation of the excited solutes and the cooling of the hot solute molecules by collisional energy transfer to the surrounding takes place in the several picoseconds that strongly depend on the properties of solvents. The difference of Lewis basicity and states density of solvents is a possible reason to explain this solvent dependence. The more basic the solvent is, which means the more interaction between the solute and the neighboring solvent shell, the more rapid the intermolecular vibrational excess energy transfer from the solute to the surroundings and the solvation of the solutes are. The higher the states density of the solvent is, the more favorable the energy transfer between the solute and solvent molecules is.

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“…[1][2][3][4][5][6][19][20][21][22][23][24][25][26][27][28][29][30] The fluorescence upconversion and pump-probe are the most popular methods. The femtosecond time-resolved stimulated emission pumping fluorescence depletion (FS TR SEP FD), which was developed by Kong and co-workers, 28 has been used to study vibrational relaxation and solvation dynamics of dye molecules and the fast singlet-triplet intersystem crossing of terthiophene.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Dynamics of Dye Molecules in Solution as a Function of Temperature

et al. 2003

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Femtosecond time-resolved studies using fluorescence depletion spectroscopy were performed on Rhodamine 700 in acetone solution and on Oxazine 750 in acetone and formamide solutions at different temperatures. The experimental curves that include both fast and slow processes have been fitted using a biexponential function. Time constants of the fast process, which corresponds to the intramolecular vibrational redistribution (IVR) of solute molecules, range from 300 to 420 fs and increase linearly as the temperature of the environment decreases. The difference of the average vibrational energy of solute molecules in the ground state at different temperatures is a possible reason that induces this IVR time-constant temperature dependence. However, the time constants of the slow process, which corresponds to the energy transfer from vibrational hot solute molecules to the surroundings occurred on a time scale of 1-50 ps, changed dramatically at lower temperature, nonlinearly increasing with the decrease of temperature. Because of the C-H‚‚‚O hydrogen-bond between acetone molecules, it is more reasonable that acetone molecules start to be associated, which can influence the energy transfer between dye molecules and acetone molecules efficiently, even at temperatures far over the freezing point.

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Resonance Raman and femtosecond absorption studies of vibrational relaxation initiated by ultrafast intramolecular proton transfer

Cited by 63 publications

References 13 publications

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin

Ultrafast Vibrational and Thermal Relaxation of Dye Molecules in Solutions

Ultrafast Dynamics of Dye Molecules in Solution as a Function of Temperature

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