Time-Resolved Study of the Solvent and Temperature Dependence of Singlet Oxygen (1Δg) Reactivity toward Enol Ethers: Reactivity Parameters Typical of Rapid Reversible Exciplex Formation

1982 ◽  
Vol 104 (25) ◽  
pp. 7098-7104 ◽  
Author(s):  
A. A. Gorman ◽  
I. R. Gould ◽  
I. Hamblett
Keyword(s):  
Singlet Oxygen ◽  
Temperature Dependence ◽  
Time Resolved ◽  
Enol Ethers ◽  
Exciplex Formation

scholarly journals Photophysical Properties of Protoporphyrin IX, Pyropheophorbide-a, and Photofrin® in Different Conditions

2021 ◽  
Vol 14 (2) ◽  
pp. 138
Author(s):  
Bauyrzhan Myrzakhmetov ◽  
Philippe Arnoux ◽  
Serge Mordon ◽  
Samir Acherar ◽  
Irina Tsoy ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Photophysical Properties ◽  
Protoporphyrin Ix ◽  
Fluorescence Emission ◽  
Solvent Polarity ◽  
Visible Absorption ◽  
Light Dosimetry ◽  
Time Resolved ◽  
Pyropheophorbide A ◽  
Influence Of Solvent

Photodynamic therapy (PDT) is an innovative treatment of malignant or diseased tissues. The effectiveness of PDT depends on light dosimetry, oxygen availability, and properties of the photosensitizer (PS). Depending on the medium, photophysical properties of the PS can change leading to increase or decrease in fluorescence emission and formation of reactive oxygen species (ROS) especially singlet oxygen (1O2). In this study, the influence of solvent polarity, viscosity, concentration, temperature, and pH medium on the photophysical properties of protoporphyrin IX, pyropheophorbide-a, and Photofrin® were investigated by UV-visible absorption, fluorescence emission, singlet oxygen emission, and time-resolved fluorescence spectroscopies.

scholarly journals Photoreactivity of Hair Melanin from Different Skin Phototypes—Contribution of Melanin Subunits to the Pigments Photoreactive Properties

2021 ◽  
Vol 22 (9) ◽  
pp. 4465
Author(s):  
Krystian Mokrzynski ◽  
Shosuke Ito ◽  
Kazumasa Wakamatsu ◽  
Theodore G. Camenish ◽  
Tadeusz Sarna ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Singlet Oxygen ◽  
Near Infrared ◽  
Paramagnetic Resonance ◽  
Time Resolved ◽  
W Band ◽  
Epr Oximetry ◽  
X Band ◽  
Hair Samples ◽  
Electron Paramagnetic

Photoreactivity of melanin has become a major focus of research due to the postulated involvement of the pigment in UVA-induced melanoma. However, most of the hitherto studies were carried out using synthetic melanin models. Thus, photoreactivity of natural melanins is yet to be systematically analyzed. Here, we examined the photoreactive properties of natural melanins isolated from hair samples obtained from donors of different skin phototypes (I, II, III, and V). X-band and W-band electron paramagnetic resonance (EPR) spectroscopy was used to examine the paramagnetic properties of the pigments. Alkaline hydrogen peroxide degradation and hydroiodic acid hydrolysis were used to determine the chemical composition of the melanins. EPR oximetry and spin trapping were used to examine the oxygen photoconsumption and photo-induced formation of superoxide anion, and time-resolved near infrared phosphorescence was employed to determine the singlet oxygen photogeneration by the melanins. The efficiency of superoxide and singlet oxygen photogeneration was related to the chemical composition of the studied melanins. Melanins from blond and chestnut hair (phototypes II and III) exhibited highest photoreactivity of all examined pigments. Moreover, melanins of these phototypes showed highest quantum efficiency of singlet oxygen photogeneration at 332 nm and 365 nm supporting the postulate of the pigment contribution in UVA-induced melanoma.

Temperature dependence of time-resolved photoluminescence of bound excitons in CuInS2 crystals

2005 ◽  
Vol 480-481 ◽  
pp. 283-285 ◽  
Author(s):  
K. Wakita ◽  
K. Nishi ◽  
Y. Ohta ◽  
T. Onishi
Keyword(s):  
Temperature Dependence ◽  
Time Resolved ◽  
Time Resolved Photoluminescence

Alkali–helium exciplex formation on the surface of helium nanodroplets. II. A time-resolved study

2000 ◽  
Vol 113 (21) ◽  
pp. 9694-9701 ◽  
Author(s):  
J. Reho ◽  
J. Higgins ◽  
K. K. Lehmann ◽  
G. Scoles
Keyword(s):  
Helium Nanodroplets ◽  
Time Resolved ◽  
Exciplex Formation

Reaction of singlet oxygen with enol ethers in the presence of acetaldehyde. Formation of 1,2,4-trioxanes

1983 ◽  
Vol 105 (21) ◽  
pp. 6498-6499 ◽  
Author(s):  
Charles W. Jefford ◽  
Shigeo Kohmoto ◽  
John Boukouvalas ◽  
Ulrich Burger
Keyword(s):  
Singlet Oxygen ◽  
Enol Ethers

scholarly journals Dynamics of Anomalous Temperature-Induced Emission Shift in MOCVD-grown (Al, In)GaN Thin Films

2000 ◽  
Vol 5 (S1) ◽  
pp. 796-802 ◽  
Author(s):  
Yong-Hoon Cho ◽  
G. H. Gainer ◽  
J. B. Lam ◽  
J. J. Song ◽  
W Yang ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Stokes Shift ◽  
Energy Shift ◽  
Peak Position ◽  
Time Resolved ◽  
Temperature Range ◽  
Al Content ◽  
Peak Energy ◽  
Emission Behavior ◽  
Pl Intensity

We present a comprehensive study of the optical characteristics of (Al, In)GaN epilayers measured by photoluminescence (PL), integrated PL intensity, and time-resolved PL spectroscopy. For not only InGaN, but also AlGaN epilayers with large Al content, we observed an anomalous PL temperature dependence: (i) an “S-shaped” PL peak energy shift (decrease-increase-decrease) and (ii) an “inverted S-shaped” full width at half maximum (FWHM) change (increase-decrease-increase) with increasing temperature. Based on time-resolved PL, the S shape (inverted S shape) of the PL peak position (FWHM) as a function of temperature, and the much smaller PL intensity decrease in the temperature range showing the anomalous emission behavior, we conclude that strong localization of carriers occurs in InGaN and even in AlGaN with rather high Al content. We observed that the following increase with increasing Al content in AlGaN epilayers: (i) a Stokes shift between the PL peak energy and the absorption edge, (ii) a redshift of the emission with decay time, (iii) the deviations of the PL peak energy, FWHM, and PL intensity from their typical temperature dependence, and (iv) the corresponding temperature range of the anomalous emission behavior. This indicates that the band-gap fluctuation responsible for these characteristics is due to energy tail states caused by non-random inhomogeneous alloy potential variations enhanced with increasing Al content.

scholarly journals Time-resolved photoluminescence on double graded Cu(In,Ga)Se2 – Impact of front surface recombination and its temperature dependence

2019 ◽  
Vol 20 (1) ◽  
pp. 313-323 ◽  
Author(s):  
Thomas Paul Weiss ◽  
Romain Carron ◽  
Max H. Wolter ◽  
Johannes Löckinger ◽  
Enrico Avancini ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Surface Recombination ◽  
Front Surface ◽  
Time Resolved ◽  
Time Resolved Photoluminescence

scholarly journals Study of Singlet Oxygen Dynamics on Silicon Polymer Matrix

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Jeong-Wook Hwang ◽  
Seung-Jin Jung ◽  
Il Heo ◽  
Hyun-A Son ◽  
Jong-Ho Kim ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Detailed Analysis ◽  
Polymer Film ◽  
Polymer Matrix ◽  
Time Resolved ◽  
Surface Component ◽  
Component C ◽  
Oxygen Dynamics ◽  
Silicone Polymer

We report a detailed analysis of singlet oxygen generated from the photofunctional polymer film (PFPF) matrix which is the silicone polymer film (PDMS) embedded with a photosensitizer. Activation and deactivation dynamics of singlet oxygen generated from PFPFs were investigated with time-resolved phosphorescence spectroscopy. The singlet oxygen generated from PFPFs was dissipated into three different regions of the polymer matrix; the inside (component A), the surface (component B), and the outside (component C). According to the deactivation dynamics of singlet oxygen in the polymer matrix, the components B and C are expected to be more important for various applications.

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