Time-resolved photothermal and photoacoustic methods applied to photoinduced processes in solution

Braslavsky, Silvia E.; Heibel, George E.

doi:10.1021/cr00014a007

Cited by 573 publications

(586 citation statements)

References 116 publications

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“…The kinetics of photothermal processes and triplet population were measured with the use of LIOAS [46,47]. The samples were illuminated by a flash GL-3300/GL301 nitrogen laser (Photon Technology Int.…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

Triplet Thermal Relaxation Study as a Probe of Weak Interdimers of Porphyrin Derivatives

2011

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This article deals with results concerning the study of interacting dyes which are able to create weak interdimers. Two groups of organic systems: phthalocyanines (di-ethanol-amine and di-octane-amine) and pyridyl porphyrins (zinc, copper, and free-base) covalently linked to polyethylene glycol (PEG) in water and organic solvents (dioxane, dimethylsulfoxide) were investigated. Absorption, fluorescence, and photoacoustics were used as experimental methods but particular attention was paid to light-induced optoacoustic spectroscopy to follow the dye's triplet population and triplet thermal relaxation to study intermolecular interactions. It has been shown that even the weak interactions of the organic dyes under study is not detectable by absorption and only slightly by fluorescence is it possible to follow interactions by complementary photothermal methods. The results obtained for selected phthalocyanines and covalent porphyrin-polymer samples evidently show that the lightinduced optoacoustic experiment is a perfect tool in the detection of weakly interacting aggregates.

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Section: Materials and Experimental Methodsmentioning

confidence: 99%

Triplet Thermal Relaxation Study as a Probe of Weak Interdimers of Porphyrin Derivatives

2011

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“…The laser beam was shaped by a 1 mm diameter pinhole in front of the cuvette, so that the resolution time in our experimental set-up, τ R , was ca. 800 ns [25]. The detecting system consisted of a 4 mm thick x 4 mm in diameter home-made ceramic piezoelectric transducer (PZT), pressed against a cuvette side wall parallel to the laser beam direction.…”

Section: Photophysical Measurementsmentioning

confidence: 99%

“…(2) [25], which was used for the handling of the LIOAS signals where the experimental constant K contains the thermo-elastic parameters of the solution as well as instrumental factors. A and α represent, respectively, the absorbance of the sample at the excitation wavelength and the fraction of the energy released to the medium as prompt heat.…”

Section: Photophysical Measurementsmentioning

confidence: 99%

“…These values combined with fluorescence data and singlet oxygen quantum yield production fit the energy balance of eq. (6) [24,25]: E a = Φ em E em + α E a + Φ st E st (6) where E em is the "0-0" luminescence energy, E a is the molar energy of the laser pulse (hc/λ exc ), E st is the molar energy content of the species formed with a quantum yield Φ st which stores energy for a time longer than the heat integration time and decays with a lifetime τ. When singlet oxygen acts as storing species, the corresponding values for this species are Φ st = Φ Δ and τ = τ Δ .…”

Section: Singlet Oxygen Generation and Lioas Experimentsmentioning

confidence: 99%

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Solvent effects on the photophysical properties of Bu4N[(4,4′-bpy)Re(CO)3(bpy-5,5′-diCOO)] complex. A combined experimental and computational study

Saavedra

Ragone

Franca

et al. 2016

Journal of Organometallic Chemistry

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The photophysical properties of the complex Bu 4 N[(4,4′-bpy)Re(CO) 3 (bpy-5,5′-diCOO)] were studied in protic and aprotic media with the aid of steady-state and time-resolved techniques and TD-DFT calculations. The absorption spectrum as well as the steady state and time resolved luminescence of the Re(I) complex display a marked solvent effect. The highest and lowest energy absorption bands experience a bathochromic shift as the polarity of the solvent decreases. In addition, the lowest energy band broadens. Two luminescence bands were observed around 430 and 600 nm in protic organic solvents like alcohols. The high energy emission is observed solely in aqueous solutions, while in aprotic solvents only the low energy luminescence is detected. TD-DFT calculations allowed us to identify the main electronic transitions in the low energy region as 1 MLLCT Re(CO) 3 → 4,4′-bpy and 1 MLLCT Re(CO) 3 → bpy-5,5′-diCOO . The simulated absorption spectra of the Re(I) complex in H 2 O, protic (EtOH, MeOH) and aprotic (CHCl 3 , CH 2 Cl 2 , CH 3 CN) organic solvents follow the experimental absorption spectra with reasonable accuracy both in position and relative intensities. The magnitude of the calculated dipole moment (μ) increases with the dielectric constant of the solvent (ε r ). Besides, the energy of 1 MLLCT Re(CO) 3 → 4,4′-bpy also increases with ε r . However, the energy of the 1 MLLCT Re(CO) 3 → bpy-5,5′-diCOO transition is rather insensitive to ε r . This disparity is attributed to the fact that the 1 MLLCT Re(CO) 3 → 4,4′-bpy transition is nearly parallel to the orientation of μ while the 1 MLLCT Re(CO) 3 → bpy-5,5′-diCOO transition is almost perpendicular to it. Unrestricted TDFT calculations were successfully applied to the triplet species. It is observed that in the triplet state the Re N distances are shortened while Re C distances are elongated relative to the ground state. The calculated emission energy by TD-DFT and/or Δ(SCF) methods was compared to the experimental emission maximum in chloroform. All the experimental results as well as the theoretical calculations indicate that solvent effects on the steady state and time resolved luminescence of the Re(I) complex can be accounted by the coexistence of 3 MLLCT Re(CO) 3 → 4,4′-bpy , 3 MLLCT Re(CO) 3 → bpy-5,5′-diCOO and 1 IL excited states.

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“…The noise showed a dependence on the absolute value of the signal. For strong signals, as is the case with solutions in ethanol or acetonitrile [7], the noise is mainly determined by the laser instability and the value of the variance for each data is a function of the channel number. In aqueous solutions the noise is essentially independent of the channel number and simply reflects the level of the electrical noise in the apparatus.…”

Section: Determination Of Errors Distributionmentioning

confidence: 99%

Data analysis in pulsed-laser, time-resolved photoacoustics : evaluation of errors distribution and confidence intervals

Campani

Viappiani

1994

J. Phys. IV France

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Time-resolved photothermal and photoacoustic methods applied to photoinduced processes in solution

Cited by 573 publications

References 116 publications

Triplet Thermal Relaxation Study as a Probe of Weak Interdimers of Porphyrin Derivatives

Triplet Thermal Relaxation Study as a Probe of Weak Interdimers of Porphyrin Derivatives

Solvent effects on the photophysical properties of Bu4N[(4,4′-bpy)Re(CO)3(bpy-5,5′-diCOO)] complex. A combined experimental and computational study

Data analysis in pulsed-laser, time-resolved photoacoustics : evaluation of errors distribution and confidence intervals

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