Experimental study of solvent effect on the heat transfer characteristics of 4-[(4-aminophenyl)-(4-imino-1-cyclohexa-2,5-dienylidene) methyl] aniline hydrochloride – A concentration based study

The thermal diffusivity calculations of 4-[(4-aminophenyl)-(4-imino-1-cyclohexa-2,5-dienylidene) methyl] aniline hydrochloride were made for four distinct concentrations of dye dissolved in three solvents. The number of dye aggregates at higher concentrations produce more random collisions. Because of this, heat diffusion will be slower and a reduced thermal diffusivity value was observed. Due to the increased number of dye molecules, cluster formation can also occur at higher concentrations which further reduces the thermal transport through the media. Fourier-transform infrared spectroscopy (FTIR) showed the vibrational bonds of the dye in the three solvents. The dye dissolved in acetone showed higher diffusivity as compared to the other two solvents. Our studies revealed that thermal diffusivity of the dye under study is strongly solvent dependent as well as concentration dependent. The dye under study could be effectively used as insulators or heat sinks with proper choice of concentration and solvent

Laser induced fluorescence based optical fiber probe for analyzing bacteria

Optical fiber based laser induced fluorescence (LIF) measurements were carried out using Rhodamine B to analyze two different species of bacteria , a Gram-positive bacteria namely Bacillus .cmithii , and fibrin alginolvticus, a Gram-' negative bacteria . The fiber sensor was clearly able to distinguish between the two species of bacteria . Quenching effect of the dye Rhodamine B by Bacillus smitltii was observed . The effect of dye on the samples was also studied in detail

Fluorescenec Emission of SrS:Eu2+ Phosphor-Energy Level Splitting of Eu2+

A method of preparation of strontium sulphide phosphors doped with europium is given. Nitrogen laser excited fluorescence emission spectra of these phosphors in the visible region are recorded. A band with line structure in the region 350-430 nm and a new broad band at 460 nm are observed. The splitting pattern for the 6p levels of Eu 2+ are given.Cochin University of Science and Technolog

Laser induced fluorescence of BaS: Sm phosphor and energy level splitting of Sm3+ ion

Fluorescence of BaS: Sm phosphor has been studied using a pulsed Nitrogen laser (337.1 nm) as the excitation source. The spectrum consists of a broad band in the region 540–660nm superposed by the characteristic Sm3+ lines. Energy level splitting pattern of Sm3+ due to crystal field effects has been calculated and relevent field parameters are evaluated. Analysis shows that Sm3+ takes up Ba2+ substitutional sites.Cochin University of Science & Technolog

Dessiign and Devellopmentt off FFiiberr Opttiicc Senssorrss fforr Qualliitty Evalluattiion off varriiouss LLiiquiid and Gasseouss Mediia

Cochin University of Science And Technolog

On the luminescence characteristics of cerium and copper doped barium sulphide phosphor

Photoluminescence, thermoluminescence and phosphorescence studies of cerium and copper doped BaS phosphors are attempted. Cu+ centres in BaS lattice activate red emission while Ce3+ sensitize the blue emission. Results are explained on the basis of superposition theory involving monomolecular kinetics. In Randall and Wilkins model, the decay and TL studies are found to corelate each other.Cochin University of Science and Technolog

Visible luminescence mechanism in nano ZnO under weak confinement regime

We describe the structure of luminescence spectrum in the visible region in nano-ZnO in colloidal and thin film forms under weak confinement regime by modeling the transition from excited state energy levels of excitons to their ground state. Measurements on nanocrystallites indicate the presence of luminescence due to excitonic emissions when excited with 255 nm. The relevant energy levels showing the transitions corresponding to the observed peaks in the emission spectrum of ZnO of particle size 18 nm are identified.Cochin University of Science and Technolog