Differential Reactivity of Upper Triplet States Produces Wavelength-Dependent Two-Photon Photosensitization Using Rose Bengal

1999 ◽  
Vol 103 (18) ◽  
pp. 3737-3741 ◽  
Author(s):  
Christopher R. Lambert ◽  
Irene E. Kochevar ◽  
Robert W. Redmond
Keyword(s):  
Rose Bengal ◽  
Triplet States ◽  
Two Photon ◽  
Differential Reactivity

scholarly journals Probing different spin states in xylyl radicals and ions

2018 ◽  
Vol 20 (10) ◽  
pp. 7180-7189 ◽  
Author(s):  
Mathias Steglich ◽  
Andras Bodi ◽  
John P. Maier ◽  
Patrick Hemberger
Keyword(s):  
Photoelectron Spectroscopy ◽  
Triplet States ◽  
Spin States ◽  
Two Photon ◽  
Benzyl Radicals ◽  
Singlet And Triplet States ◽  
Photon Ionization

Resonant one-color two-photon ionization spectroscopy and mass-selected threshold photoelectron spectroscopy were applied to study the electronic doublet states of the three xylyl (methyl-benzyl) radicals above 3.9 eV as well as the singlet and triplet states of the cations up to 10.5 eV.

scholarly journals Dynamic quenching of porphyrin triplet states by two-photon absorbing dyes: Towards two-photon-enhanced oxygen nanosensors

2008 ◽  
Vol 198 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Olga S. Finikova ◽  
Ping Chen ◽  
Zhongping Ou ◽  
Karl M. Kadish ◽  
Sergei A. Vinogradov
Keyword(s):  
Triplet States ◽  
Dynamic Quenching ◽  
Two Photon

scholarly journals Design of metalloporphyrin-based dendritic nanoprobes for two-photon microscopy of oxygen

2008 ◽  
Vol 12 (12) ◽  
pp. 1261-1269 ◽  
Author(s):  
Artem Y. Lebedev ◽  
Thomas Troxler ◽  
Sergei A. Vinogradov
Keyword(s):  
Electron Transfer ◽  
Energy Transfer ◽  
Dynamic Range ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Triplet States ◽  
Redox Potentials ◽  
Oxygen Quenching ◽  
Two Photon Microscopy ◽  
Two Photon

Metalloporphyrin-based phosphorescent nanoprobes are being developed for two-photon microscopy of oxygen. In these molecular constructs, the generation of porphyrin triplet states following two-photon excitation is induced by the intramolecular Förster-type resonance energy transfer from a covalently attached 2P antenna. In the earlier developed prototypes, electron transfer between the antenna and the metalloporphyrin strongly interferred with the phosphorescence, reducing the sensitivity and the dynamic range of the sensors. By tuning the distances between the antenna and the core, and adjusting their redox potentials, the unwanted electron transfer could be prevented. An array of phosphorescent Pt porphyrins (energy transfer acceptors) and 2P dyes (energy transfer donors) was screened using dynamic quenching of phosphorescence, and the FRET-pair with the minimal ET rate was identified. This pair, consisting of Coumarin-343 and Pt meso-tetra-(4-alkoxyphenyl)porphyrin, was used to construct a probe in which the antenna fragments were linked to the termini of G3 poly(arylglycine) (AG) dendrimer with PtP core. The folded dendrimer formed an insulating layer between the porphyrin and the antenna, simultaneously controlling the rate of oxygen quenching (Stern-Volmer oxygen quenching constant). Modification of the dendrimer periphery with oligoethyleneglycol residues made the probe's signal insensitive to the presence of proteins and other macromolecular solutes.

Z-SCAN APPROACH FOR MEASURING THE THRESHOLD OF TWO-PHOTON PHOTOPOLYMERIZATION

2005 ◽  
Vol 14 (01) ◽  
pp. 79-84 ◽  
Author(s):  
YURI BOIKO
Keyword(s):  
Thin Film ◽  
Laser Beam ◽  
Fundamental Frequency ◽  
Rose Bengal ◽  
Nd:Yag Laser ◽  
Sensitive Material ◽  
Two Photon ◽  
Threshold Data ◽  
532 Nm

A technique is suggested to measure the threshold of two-photon initiated photopolymerization involving a Z-scan of a thin film of sensitive material along the focusing axis of the laser beam. A condition of reaching the threshold when scanning the sample along Z-direction is identified via interferometric effect. The technique is demonstrated for measurements employing Nd:YAG laser in nanosecond regime with fundamental frequency 1064 nm and its harmonic of 532 nm. Threshold data are presented for particular systems, indicating a threshold of 5 GW/cm2 for a system based on Rose Bengal exposed by a 1064 nm nanosecond-pulsed radiation and 0.05 GW/cm2 for Darocur initiators exposed to 532 nm.

Isomérisation photosensibilisée par des colorants et photoréduction de l'azobenzène en solution. II

1974 ◽  
Vol 52 (10) ◽  
pp. 1858-1867 ◽  
Author(s):  
Jacques Ronayette ◽  
René Arnaud ◽  
Jacques Lemaire
Keyword(s):  
Methylene Blue ◽  
Energy Transfer ◽  
Quantum Yield ◽  
Rose Bengal ◽  
Experimental Results ◽  
The Other ◽  
Eosin Y ◽  
Triplet States ◽  
Trans Form ◽  
Photochemical Isomerization

The photochemical isomerization of azobenzene in solution can be sensitized by dyes which have low-lying triplet states (rose Bengal, eosin Y, fluorescein, methylene blue) but cannot be inhibited by such compounds. The two triplet levels, Tβc and Tαc of the cis form are indistinguishable experimentally. On the other hand, the experimental results verify the existence of two triplet levels, Tβt and Tαt, with different properties, in the trans form. Population, by energy transfer, of the lower triplet, Tαt, leads to isomerization with a quantum yield near 0.5, whereas population of the triplet Tβt only rarely leads to isomerization (quantum yield about 0.03).The photoreduction of azobenzene in isopropanol also has been studied. Only the cis form is photoreducible and it is very difficult experimentally to determine whether this photoreduction can be sensitized.A Jablonski diagram of the two forms of azobenzene is presented to correlate these observations. [Journal translation]

On the Mechanism of Quenching by Amines: A New Method for Investigation of Interactions with Triplet States

1974 ◽  
Vol 52 (16) ◽  
pp. 2889-2893 ◽  
Author(s):  
Robert H. Young ◽  
D. Brewer ◽  
R. Kayser ◽  
R. Martin ◽  
D. Feriozi ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Charge Transfer ◽  
Singlet Oxygen ◽  
Rose Bengal ◽  
Rate Constants ◽  
Direct Method ◽  
Diffusion Limit ◽  
Triplet States ◽  
Novel Approach ◽  
Series Of Experiments

Rate constants for the quenching of singlet oxygen by a series of substituted N,N-dimethylanilines were obtained by a direct method employing a dye-laser. The Hammett ρ value obtained from the data (−1.71) suggests that a (partial) charge-transfer complex may be responsible for the quenching action. This rate data was combined with that obtained for the total quenching action on the sensitized photooxidation of 1,3-diphenylfuran. The quenching action on the photooxidation reaction is due to both the quenching of singlet oxygen and the quenching of the triplet state of the sensitizer (rose bengal or methylene blue). The combination of the data from each series of experiments resulted in rate constants of quenching of the triplet states of the sensitizers. A number of the N,N-dimethylanilines quenched the triplet states at the diffusion limit. Hammett ρ values (−1.86 for rose bengal and −4.19 for methylene blue) indicate that charge-transfer intermediates are probably responsible for the quenching action. This was confirmed by the observation of a transient intermediate assigned to the charge-transfer radical of methylene blue. The technique used here represents a novel approach to the investigation of triplet states.

Two-Photon Chemistry from Upper Triplet States of Thymine

2013 ◽  
Vol 135 (44) ◽  
pp. 16714-16719 ◽  
Author(s):  
Victoria Vendrell-Criado ◽  
Gemma M. Rodríguez-Muñiz ◽  
Minoru Yamaji ◽  
Virginie Lhiaubet-Vallet ◽  
M. Consuelo Cuquerella ◽  
...  
Keyword(s):  
Triplet States ◽  
Two Photon

scholarly journals Depth-targeted intracortical microstroke by two-photon photothrombosis in rodent brain

2021 ◽  
Author(s):  
Masahiro Fukuda ◽  
Toshio Suda ◽  
Takayoshi Matsumura ◽  
Hajime Hirase
Keyword(s):  
Blood Flow ◽  
Rose Bengal ◽  
Blood Stream ◽  
Target Vessel ◽  
Vessel Occlusion ◽  
Two Photon ◽  
Single Vessel ◽  
Cortical Parenchyma ◽  
Photon Excitation ◽  
Two Photon Excitation

Significance: Photothrombosis is a widely used model of ischemic stroke in rodent experiments. In the photothromboris model, the photosensitizer Rose Bengal is systemically introduced to the blood stream and activated by green light to induce aggregation of platelets that eventually cause vessel occlusion. Since the activation of Rose Bengal is a one-photon phenomenon and the molecules in the illuminated area (light path) are subject to excitation, targeting of thrombosis is unspecific especially in the depth dimension. We have developed a photothrombosis protocol that can target a single vessel in the cortical parenchyma by two-photon excitation. Aim: We aim to induce a thrombotic stroke in the cortical parenchyma by two-photon activation of Rose Bengal so that we confine photothrombosis within a vessel of a target depth. Approach: FITC-dextran is injected into the blood stream to visualize the cerebral blood flow in anesthetized adult mice with a cranial window. After a target vessel is chosen by two-photon imaging (950 nm), Rose Bengal is injected into the blood stream. The scanning wavelength is changed to 720 nm and photothrombosis was induced by scanning the target vessel. Results: Two-photon depth-targeted single vessel photothrombosis was achieved with a success rate of 84.9+/-1.7% within 80 s. Attempts without Rose Bengal (i.e., only with FITC) did not result in photothrombosis at the excitation wavelength of 720 nm. Conclusions: We described a protocol that achieves depth-targeted single vessel photothrombosis by two-photon excitation. Simultaneous imaging of blood flow in the targeted vessel using FITC dextran enabled the confirmation of vessel occlusion and prevention of excess irradiation that possibly induces unintended photodamage.

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