Study of Energy Transfer in Organic Dye Pairs Using Thermal Lens Technique

Kurian, Achamma; Unnikrishnan, K. P.; Gopinath, Pramod; Nampoori, V. P. N.; Vallabhan, C. P. G.

doi:10.1142/s0218863501000759

Cited by 14 publications

(6 citation statements)

References 25 publications

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“…The propagation of the probe beam through the thermal lens will result in either a spreading or a focusing of the beam center, depending upon the temperature coefficient of the thermal expansion. The TL effect has been exploited for a number of measurements such as determination of absorptivities as low as 10 À7 cm À1 , evaluation of triplet quantum yield in solid and liquid phases, the study of multiphoton processes, thermal diffusivity of various solvents, calorimetric trace analysis, food stuff analysis and electronic energy transfer studies [15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Studies on Fluorescence Efficiency and Photodegradation of Rhodamine 6G Doped PMMA Using a Dual Beam Thermal Lens Technique

et al. 2002

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In this paper we report the use of the dual beam thermal lens technique as a quantitative method to determine absolute fluorescence quantum efficiency and concentration quenching of fluorescence emission from rhodamine 6G doped Poly(methyl methacrylate) (PMMA), prepared with different concentrations of the dye. A comparison of the present data with that reported in the literature indicates that the observed variation of fluorescence quantum yield with respect to the dye concentration follows a similar profile as in the earlier reported observations on rhodamine 6G in solution. The photodegradation of the dye molecules under cw laser excitation is also studied using the present method.

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Section: Introductionmentioning

confidence: 99%

Studies on Fluorescence Efficiency and Photodegradation of Rhodamine 6G Doped PMMA Using a Dual Beam Thermal Lens Technique

et al. 2002

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“…As the volume fraction of ZnO increases, the formation of aggregates decreases the fluorescence emission. 76 This can be related to the phenomenon of re-absorption and emission at higher concentrations which ultimately reduces the fluorescence emission. As the volume fraction increases, the low frequency tail of the absorption spectrum of the sample overlaps with the high frequency end of its fluorescence spectrum.…”

Section: Fluorescence Spectroscopymentioning

confidence: 99%

Spectral and Nonlinear Optical Characteristics of ZnO Nanocomposites

Irimpan¹,

Nampoori²,

Radhakrishnan³

2010

sci adv mat

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The spectral and nonlinear optical properties of ZnO based nanocomposites prepared by colloidal chemical synthesis are investigated. Very strong UV emissions are observed from ZnO-Ag, ZnO-Cu and ZnO-SiO 2 nanocomposites. The strongest visible emission of a typical ZnO-Cu nanocomposite is over ten times stronger than that of pure Cu due to transition from deep donor level to the copper induced level. The optical band gap of ZnO-CdS and ZnO-TiO 2 nanocomposites is tunable and emission peaks changes almost in proportion to changes in band gap. Nonlinear optical response of these nanocomposites is studied using nanosecond laser pulses from a tunable laser in the wavelength range of 450-650 nm at resonance and off-resonance wavelengths. The nonlinear response is wavelength dependent and switching from RSA to SA has been observed at resonant wavelengths. Such a change-over is related to the interplay of plasmon/exciton band bleach and optical limiting mechanisms. The observed nonlinear absorption is explained through two photon absorption followed by weak free carrier absoption, interband absorption and nonlinear scattering mechanisms. The nonlinearity of the silica colloid is low and its nonlinear response can be improved by making composites with ZnO and ZnO-TiO 2 . The increase of the third-order nonlinearity in the composites can be attributed to the enhancement of exciton oscillator strength. This study is important in identifying the spectral range and the composition over which the nonlinear material acts as an RSA based optical limiter. These nanocomposites can be used as optical limiters and are potential materials for the light emission and for the development of nonlinear optical devices with a relatively small limiting threshold.

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“…This comprises the determination of low optical absorption coefficients, 20,21 Soret effect, 22 investigation of photobleaching processes, characterization of mass and thermal diffusion properties of fuels and biofuels, [23][24][25][26] dyes, [27][28][29] micellar solutions, 30 and photosensitizers. [31][32][33][34] The method can also be used to study thermal and optical properties of polymers and glasses, [35][36][37][38][39][40] in addition to the pharmacological and biological applications and determination of heavy metals. [41][42][43][44][45] There have been several reviews on TL applications in the literature.…”

Section: Introductionmentioning

confidence: 99%

From Protohypericin to Hypericin: Photoconversion Analysis Using a Time-Resolved Thermal Lens Technique

et al. 2019

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Hypericin (Hyp) is a natural compound with interesting photophysical and pharmacological properties, which has been used in photodynamic therapy and photodynamic inactivation of microorganisms. Its synthesis is based on a series of chemical processes that ends with a light–drug interaction by the photoconversion of protohypericin (pHyp) to Hyp. Although this photosensitizer is used in a variety of medical applications, the photophysical and photochemical mechanisms involved in the final step related to the photo production of Hyp are not completely understood at the molecular level. Protohypericin concentration, solvents, light irradiation under different wavelengths, and a sort of variables could play an important role in predicting the yielding of this photoconversion process. Here, we used the high-sensitive and remote measurement characteristics of the time-resolved thermal lens technique to investigate the relation between the light-induced photoconversion rate of pHyp to Hyp and the initial concentration pHyp. The results show a linear dependence of the photoreaction rate with the concentration of pHyp, indicating that the overall reaction process includes steps comprising the formation of distinct intermediate species. We demonstrate the applicability of the thermal lens technique for the photochemical characterization of photosensitive drugs at low concentration levels.

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Study of Energy Transfer in Organic Dye Pairs Using Thermal Lens Technique

Cited by 14 publications

References 25 publications

Studies on Fluorescence Efficiency and Photodegradation of Rhodamine 6G Doped PMMA Using a Dual Beam Thermal Lens Technique

Studies on Fluorescence Efficiency and Photodegradation of Rhodamine 6G Doped PMMA Using a Dual Beam Thermal Lens Technique

Spectral and Nonlinear Optical Characteristics of ZnO Nanocomposites

From Protohypericin to Hypericin: Photoconversion Analysis Using a Time-Resolved Thermal Lens Technique

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