scholarly journals Effect of Rate and Quantum Yield of 1-alkyl-2-(arylazo) Imidazoles on the Surface of Silver Nps

2021 ◽  
Vol 37 (5) ◽  
pp. 1229-1234
Author(s):  
Pallab Gayen
Keyword(s):  
Quantum Yield ◽  
Solvent Polarity ◽  
Optical Excitation ◽  
Free State ◽  
Inclusion Phase ◽  
Silver Nps ◽  
Foreign Molecule ◽  
Light Excitation ◽  
In Trans ◽  
Higher Temperature

1-Alkyl-2-(arylazo)imidazole(RaaiR/) exists in trans-structure about –N=N- bond at ambient condition. Upon optical excitation in UV region the trans-RaaiR/ isomerises to cis-RaaiR/. The photochromism is very susceptible to internal substituents and external environment like solvent polarity, viscosity and presence of innocent foreign molecule. The changes from cis-to-trans occurs slowly in visible light excitation it has significantly faster rate at higher temperature. In this work we have studied the effect of silver nanoparticle on the photochromic activity of RaaiR/. The quantum yield of the photoisomerisation is dropped by 9-27% in inclusion phase AgNPs@RaaiR/ than free state and the order of rate is: free state > silver nano particle. The activation energy (Ea) of cis to trans isomerisation is also diminished compared to free state of photochrome.

Transient Photoconductivity in Polyacetylene and Polydiacetylene

1987 ◽  
Vol 109 ◽  
Author(s):  
D. Moses ◽  
S. Phillips ◽  
M. Sinclair ◽  
A. J. Heeger
Keyword(s):  
Quantum Yield ◽  
Conducting Polymers ◽  
Single Crystal ◽  
Conjugated Polymer ◽  
Crystal Form ◽  
Transport Mechanisms ◽  
Polymeric Systems ◽  
Transient Photoconductivity ◽  
Time Regime ◽  
In Trans

ABSTRACTConducting polymers have been found to be rather good photoconductors in the sub-nansecond time regime. The TP measurement is an effective probe for determining carrier photogeneration quantum yield as well as for investigating transport mechanisms. Here, we present a short survey of our results for a few interesting polymeric systems. We start with the trans-(CH)x grown by the Shirakawa method. We then compared the TP results to those obtained from PDA-TS which currently is the only conjugated polymer in single crystal form. From this comparison, we are able to gauge the improvements in the material quality as was demonstrated by recent TP in trans-(CH)x grown by the Naarmann method

scholarly journals Optimization of Optical Excitation of Upconversion Nanoparticles for Rapid Microscopy and Deeper Tissue Imaging with Higher Quantum Yield

Theranostics ◽  
2013 ◽  
Vol 3 (5) ◽  
pp. 306-316 ◽  
Author(s):  
Qiuqiang Zhan ◽  
Sailing He ◽  
Jun Qian ◽  
Hao Cheng ◽  
Fuhong Cai
Keyword(s):  
Quantum Yield ◽  
Optical Excitation ◽  
Tissue Imaging ◽  
Upconversion Nanoparticles

Optomechanical Control of Quantum Yield in Trans -Cis Ultrafast Photoisomerization of a Retinal Chromophore Model

2017 ◽  
Vol 56 (14) ◽  
pp. 3842-3846 ◽  
Author(s):  
Alessio Valentini ◽  
Daniel Rivero ◽  
Felipe Zapata ◽  
Cristina García-Iriepa ◽  
Marco Marazzi ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Retinal Chromophore ◽  
In Trans

scholarly journals CNDO/S-CI Calculations of some Carbonyl-containing Organic Luminophores with a Stilbene Subchromophore

1985 ◽  
Vol 40 (8) ◽  
pp. 859-863
Author(s):  
G. Olbrich ◽  
P. Nikolov ◽  
F. Fratev ◽  
O. E. Polansky
Keyword(s):  
Quantum Yield ◽  
Fluorescence Quantum Yield ◽  
Electronic States ◽  
Solvent Polarity ◽  
Energy Separation ◽  
Triplet States ◽  
Organic Luminophores ◽  
Calculated Energy ◽  
Singlet And Triplet States ◽  
Ci Calculations

For a series of carbonyl-containing compounds with a stilbene subchromophore the lowest ten singlet and triplet states have been calculated with the aid of the CNDO/S-CI method. The results were used to rationalize the relative ordering of the lowest-lying S(ππ*), S(ππ*), T(ππ*), and T(ππ*) electronic states. Using the calculated energy separation between the singlet ππ*and nπ* states and between the singlet ππ* and triplet nπ* states the fluorescence ability of the compounds studied is interpreted. The connection between the structure of the compounds and their fluorescence is discussed. It is shown that an increase of the solvent polarity in some cases may lead to an inversion of the singlet nπ* and ππ* levels and to an enhancement of the fluorescence quantum yield.

scholarly journals Quantifying Triplet State Formation in Zinc Dipyrrin Complexes

2019 ◽  
Author(s):  
Norah Z. Alqahtani ◽  
Toni G. Blevins ◽  
Catherine McCusker
Keyword(s):  
Quantum Yield ◽  
Triplet State ◽  
State Formation ◽  
Transient Absorption ◽  
Photophysical Properties ◽  
Solvent Polarity ◽  
Transient Absorption Spectroscopy ◽  
Heavy Atoms ◽  
Earth Abundant ◽  
Photocatalytic Reactions

Photocatalysis is a promising method to harness solar energy and use it to form fuels and other high value chemicals, but most sensitizers used in photocatalytic reactions are complexes of rare and expensive metals such as ruthenium and iridium. Zinc dipyrromethene complexes have potential to be a more earth-abundant alternative, but their photophysical properties are largely unexplored. In this study, triplet state formation was quantified in two zinc dipyrromethene complexes, with a and without heavy atoms, by transient absorption spectroscopy. Without heavy atoms the triplet quantum yield was 16% in toluene and 27% in THF. With the addition of heavy I atoms the triplet quantum yield is increased to 62-63% and is insensitive to solvent polarity. These triplet yields meet or exceed those of successful organic photosensitizers, illustrating the potential for zinc dipyrromethene complexes as photosensitizers

A Study of the Optical Properties of Triazene-Cinnamic Acid Polymeric Fluorescent Brighteners

2012 ◽  
Vol 184-185 ◽  
pp. 868-871
Author(s):  
Jing Liu
Keyword(s):  
Optical Properties ◽  
Quantum Yield ◽  
Aqueous Solutions ◽  
Cinnamic Acid ◽  
Fluorescence Quantum Yield ◽  
Solvent Polarity ◽  
Polymerization Reaction ◽  
Dimethyl Formamide ◽  
Coating Application ◽  
Light Stability

Series of the triazene-cinnamic acid polymeric fluorescent brighteners were synthesized through three-step condensation reactions and polymerization reaction with styrene under replacing one of amino compounds of traditional fluorescent brighteners by cinnamic acid. The optical properties in aqueous solutions and N,N’- dimethyl formamide as well as paper coating application test were evaluated. The results showed that the light stability and fluorescence quantum yield of polymeric fluorescent brighteners was improved obviously and photoinduced isomerization was lower. Meanwhile the optical properties of polymeric fluorescent brightener were affected by concentration and solvent polarity, fluorescence quantum yield increasing and hypochromatic shift of fluorescence emmission wavelength with the decrease of solvent polarity. When the concentration was over 1 10-4 g/mL, the fluorescence was quenched.

scholarly journals Photophysical Approach of Biological Active Benzofuran Derivatized Pyrrole with Green Synthesized Silver NPs Using C. Roseus Leaves: Computational and Spectroscopic Study

2021 ◽  
Author(s):  
Shivaprasadagouda Patil ◽  
Mahanthesh M. Basanagouda ◽  
Sudhir M. Hiremath ◽  
Aishwarya Nadgir ◽  
Malatesh S Pujar ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Excited State ◽  
Molecular Orbital ◽  
Ground State ◽  
Solvent Polarity ◽  
Ag Nps ◽  
Ground State Dipole Moment ◽  
Computational Calculations ◽  
Silver Nps ◽  
Excited State Dipole Moment

Abstract The electronic absorption and fluorescence emission spectra of N-(2,5-dimethyl-pyrrol-1-yl)-2-(5-methoxybenzofuran-3-yl)acetamide (DPMA) molecule were recorded in various solvents at room temperature with the aim of estimation of ground state (\({\mu }_{g}\)) and excited states (\({\mu }_{e}\)) dipole moments using Lippert’s, Bakshiev’s and Kawski-Chamma-Viallete’s equations. The results were signified that, the excited state dipole moment is greater than the ground state dipole moment, which indicates the excited state dipole moment is more polar than the ground state dipole moment. Ecofriendly green synthesis of silver nanoparticles (Ag NPs) were synthesized using catharanthus roseus (C.R) leaf extract was done. These synthesized Ag NPs were used as fluorescence quenchers. Fluorescence lifetime measurement is carried out using time correlated single photon counting technique of DPMA molecule with various concentrations of Ag NPs. A linear Stern-Volmer (S-V) plot was obtained in steady state and transient state method. Furthermore we have estimated computational calculations such as ground state optimized geometry, molecular electrostatic potential (MEP), highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), experimental and theoretical energy band gap, solvent polarity and normalized solvent polarity values. Morphology and sizes of green synthesized silver NPs were characterized by transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy (EDX) and also characterized by UV-Visible absorption.

The α(C—C)/β(C—H) ratio of the primary processes in the 184.9 nm photolysis of gaseous cis- and trans-2-butene

1987 ◽  
Vol 65 (7) ◽  
pp. 1631-1638 ◽  
Author(s):  
Hélène Deslauriers ◽  
Wlodzimiercz Makulski ◽  
Guy J. Collin
Keyword(s):  
Quantum Yield ◽  
Gas Phase ◽  
Molecular Property ◽  
Bond Rupture ◽  
Complete Study ◽  
Yield Values ◽  
In Trans ◽  
Cis And Trans ◽  
In Cis

A complete study of the 184.9 nm photolysis of cis- and trans-2-butene has been done in the gas phase. The main primary processes (>90%) are the α(C—C) and β(C—H) bond ruptures. Both processes have similar quantum yield values in cis-2-butene: [Formula: see text]. Conversely, the α(C—C) bond rupture is more important in trans-2-butene: [Formula: see text]. These values are compared with those measured in propene (0.57) and isobutene (0.95). No simple molecular property seems sufficient to explain such an effect.

scholarly journals Quantifying Triplet State Formation in Zinc Dipyrrin Complexes

2019 ◽  
Author(s):  
Norah Z. Alqahtani ◽  
Toni G. Blevins ◽  
Catherine McCusker
Keyword(s):  
Quantum Yield ◽  
Triplet State ◽  
State Formation ◽  
Transient Absorption ◽  
Photophysical Properties ◽  
Solvent Polarity ◽  
Transient Absorption Spectroscopy ◽  
Heavy Atoms ◽  
Earth Abundant ◽  
Photocatalytic Reactions

Photocatalysis is a promising method to harness solar energy and use it to form fuels and other high value chemicals, but most sensitizers used in photocatalytic reactions are complexes of rare and expensive metals such as ruthenium and iridium. Zinc dipyrromethene complexes have potential to be a more earth-abundant alternative, but their photophysical properties are largely unexplored. In this study, triplet state formation was quantified in two zinc dipyrromethene complexes, with a and without heavy atoms, by transient absorption spectroscopy. Without heavy atoms the triplet quantum yield was 16% in toluene and 27% in THF. With the addition of heavy I atoms the triplet quantum yield is increased to 62-63% and is insensitive to solvent polarity. These triplet yields meet or exceed those of successful organic photosensitizers, illustrating the potential for zinc dipyrromethene complexes as photosensitizers

Sign in / Sign up

Export Citation Format

Share Document