Ultrafast Dynamics of Metal Complexes of Tetrasulfonated Phthalocyanines at Biological Interfaces: Comparison between Photochemistry in Solutions, Films, and Noncancerous and Cancerous Human Breast Tissues

International audienceA promising material in medicine, electronics, opto-electronics, electrochemistry, catalysis, and photophysics, Al(III) phthalocyanine chloride tetrasulfonic acid (AlPcS4) is investigated at biological interfaces of human breast tissue by means of steady-state and time-resolved pump?probe spectroscopies: IR, Raman, UV?vis, fluorescence, and electronic transient absorption by pump?probe spectroscopy. Spectrally resolved pump?probe data were recorded on time scales ranging from femtoseconds to nanoseconds and give insight into molecular interactions and primary events in the interfacial region. The nature of these fast processes and pathways of the competing relaxation processes from the initially excited electronic states in AlPcS4 films and at biological interfaces of human breast cancerous and noncancerous tissues is studied. Comparison between photochemical dynamics in the biological environment of the human breast tissues and that occurring in aqueous solutions is presented. The excited-state absorption (ESA) decays and bleaching recovery of the ground state have been fitted in the time window extending to nanoseconds (0?1 ns). We found that the excited-state dynamics of AlPcS4 at biological interfaces of human breast tissue is extremely sensitive to the biological environment and differs drastically from that observed in solutions and films. We demonstrated that the ultrafast dynamics at biological interfaces is described by three time constants in the ranges of 110?170 fs, 1?7 ps, and 20?60 ps. We were able to ascribe these three time constants to the primary events occurring in phthalocyanine at biological interfaces. The shortest time constants have been assigned to vibrational wavepacket dynamics in the Franck?Condon region down to the local minimum of the excited-state S1. The 1?7 ps components have been assigned to vibrational relaxation in the excited and ground electronic states. In contrast to the dynamics observed in aqueous solutions with the components in the range of 150?500 ps assigned to decay from S1 to the ground electronic state, these slow components have not been recorded in human breast tissue. We have shown that the lifetimes characterizing the first excited-state S1 in the interfacial regions of the breast tissue are markedly shorter than those in solution. It suggests that molecular structures responsible for harvesting of the light energy in biological tissue find their own ways for recovery through some special features of the potential energy surfaces such as conical intersections, which facilitate the rate of radiationless transitions. We found that the dynamics of photosensitizers in normal (noncancerous) breast tissue is markedly faster than that in cancerous tissue

Unraveling the mechanism of NO ligand photoisomerism by time-resolved infrared spectroscopy

International audienceUV-Vis- and infrared femtosecond spectroscopy makes it possible to reveal all different steps of photochemical reactions after the electronic excitation. The electronic relaxations are observed in the UV-Vis spectral range whereas the nuclear motions are monitored in the infrared spectral range. We used femtosecond time-resolved infrared spectroscopy to demonstrate the photoisomerization of the NO ligand photoinduced by a visible femtosecond pulse in a Na2[Fe(CN)5NO]*2H2O single crystal occurs in about 350 fs. The analysis of data makes it possible to unravel the mechanism leading to the photoisomerization of the NO ligand

Ultrafast Dynamics of Metal Complexes of Tetrasulphonated Phthalocyanines

International audienceA promising material in medicine, electronics, optoelectronics, electrochemistry, catalysis, and photophysics, tetrasulphonated aluminum phthalocyanine (AlPcS4), is investigated by means of steady-state and time-resolved pump?probe spectroscopies. Absorption and steady-state fluorescence spectroscopy indicate that AlPcS4 is essentially monomeric. Spectrally resolved pump-probe data are recorded on time scales ranging from femtoseconds to nanoseconds. The nature of these fast processes and pathways of the competing relaxation processes from the initially excited electronic states in aqueous and organic (dimethyl sulfoxide) solutions are discussed. The decays and bleaching recovery have been fitted in the ultrafast window (0-10 ps) and later time window extending to nanoseconds (0-1 ns). While the excited-state dynamics have been found to be sensitive to the solvent environment, we were able to show that the fast dynamics is described by three time constants in the ranges of 115-500 fs, 2-25 ps, and 150-500 ps. We were able to ascribe these three time constants to different processes. The shortest time constants have been assigned to vibrational wavepacket dynamics. The few picosecond components have been assigned to vibrational relaxation in the excited electronic states. Finally, the 150-500 ps components represent the decay from S1 to the ground state. The experimental and theoretical treatment proposed in this paper provides a basis for a substantial revision of the commonly accepted interpretation of the Soret transition (B transition) that exists in the literature

Optical Data Storage in Photosensitive Glasses and Spin State Transition Compounds

Non

Simulation of an optically induced asymmetric deformation of a liquid-liquid interface

Deformations of liquid interfaces by the optical radiation pressure of a focused laser wave were generally expected to display similar behavior, whatever the direction of propagation of the incident beam. Recent experiments showed that the invariance of interface deformations with respect to the direction of propagation of the incident wave is broken at high laser intensities. In the case of a beam propagating from the liquid of smaller refractive index to that of larger one, the interface remains stable, forming a nipple-like shape, while for the opposite direction of propagation, an instability occurs, leading to a long needle-like deformation emitting micro-droplets. While an analytical model successfully predicts the equilibrium shape of weakly deformed interface, very few work has been accomplished in the regime of large interface deformations. In this work, we use the Boundary Integral Element Method (BIEM) to compute the evolution of the shape of a fluid-fluid interface under the effect of a continuous laser wave, and we compare our numerical simulations to experimental data in the regime of large deformations for both upward and downward beam propagation. We confirm the invariance breakdown observed experimentally and find good agreement between predicted and experimental interface hump heights below the instability threshold

Femtosecond OPO pumped by a high power ytterbium rod-type fiber laser mode locked at harmonic repetition rates

We report on an optical parametric oscillator (OPO) pumped by femtosecond pulses delivered by a large-mode-area, ytterbium-doped, rod-type fiber laser. This femtosecond laser that is mode locked at harmonic repetition rates of 108 MHz, 216 MHz, and 324 MHz provides an average output power of more than 4.5 W and tens of nJ per pulse. The repetition rate is changed by adjusting the pulse polarization inside the laser cavity. Remarkably, at all these repetition rates and without any modification to the cavity, the OPO delivers femtosecond signal pulses that are tunable from 1450 nm to 1700 nm, with an average output power higher than 1 W. Increasing the pump power of the rod-type fiber and decreasing the transmission of the OPO output coupler, we were able to run the OPO at 540 MHz

Etude des non-linearites optiques dans les melanges liquides binaires critiques

SIGLEINIST TD 20005 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Fiber optical parametric oscillator delivering signal pulse tunable in wavelength and pulse duration

We designed and built an optical parametric oscillator based on a PCF fiber. Pumped by an ytterbium picosecond oscillators, it delivers signal pulses tunable in wavelength and pulse duration. Its performances and capabilities are analyzed

Nonlinear optics: Terahertz Kerr effect

The optical Kerr effect is a well-known phenomenon in which an electric field creates birefringence in a material. Researchers have now demonstrated this effect using single-cycle terahertz pulses - instead of optical pulses - in a variety of liquid

Nonlinear optics: Terahertz Kerr effect

The optical Kerr effect is a well-known phenomenon in which an electric field creates birefringence in a material. Researchers have now demonstrated this effect using single-cycle terahertz pulses - instead of optical pulses - in a variety of liquid