INVESTIGATION IN SPECTROSCOPIC CHARACTERISTICS OFRHODAMINE C IN 1- BUTANOL

Slafa I. Ibrahim, M.K. Abood and K.S. Rida Energy and Renewable Energies Technology Center, University of Technology, Baghdad, Iraq. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 10 July 2020 Final Accepted: 14 August 2020 Published: September 2020 This research investigation is interesting to obtain information of absorption and fluorescence spectrum of the Rhodamine C dye in 1butanol and the variations which happened in diverse concentration (1*10 -5 , 2*10 -5 , 4*10 -5 , 6*10 -5 , 8*10 -5 and 1*10 -4 ) mole/l at ambient temperature.The outcomes obtained showed thatthere was a red shift with increasing concentration,theenergy gaps decreasingfrom (2.168 to 2.1 eV)with increasing concentration. Also the extinction coefficient, real and imaginarydielectric constants are in agreement with resulteddata. Copy Right, IJAR, 2020,. All rights reserved.

The influence of solvents on the absorption spectrum and on the effectiveness of organic dyes was studied since the last century. As is known, the "photo-physical" behavior of a solved dye depends on the kind of its environment such as (intensity, shape).The solvent nature and "solvent-solute interactions" effects on the maximum wavelength of the dye absorption band. This influence is exceedingly related to the kind and degree of interactions between dye and solvent [4].Therefore,Rhodamine dyes are sensitive to the conditions in which preparations are made and the nature of solutions used, whether acidic or alkaline [5].
Organic dyes dissolved in appropriate solvents have been widely used as laser media for many years. Which have contributed to a wide coverage of wavelength and the tunability in addition to the important fluorescence yield , but their applications have been limited (because of the toxicity, evaporation, inflammability, etc.) of some solvents, and some restrictions have been put on their use and make them in specific applications [6].The spectroscopic properties of dyes with moieties electron donor and acceptor have received great attention due to salability of fluorescence probes. Fluid mixing in aqueous solution can be quantified by used fluorescent dyes .Two fluorescent dyes can be separated optically using a general technique including fluorescence rationing [7].
The most effective Rhodamine derivatives are getting by replacing hydrogen of the Rhodamine dye skeleton by groups such as alkyls, amines, etc. This replacing will change the "ground state" and "excited state" dipole moments of exchanged Rhodamine molecules in addition to its "photo-physical" properties. Along with changes, influence of solvents in solutions play an important role in difference of "photo-physical" properties. .The extent interactions ISSN: 2320-5407 Int. J. Adv. Res. 8(09), 241-250 242 between solute-solvent relied on solvent "relative permittivity" and "refractive index" in addition to the "dipole moment" for the solute [8].
This research is a continuation of the research series carried out by the team of researchers at the Center for Energy Technology and Renewable Energies at the University of Technology, Baghdad, Iraq [9][10][11][12].
The devices utilized in this research include "Refractometer" from" (Bellingham and Stanley Ltd, Tunbridgewells, ABBE60, England) ", the excitation and emission spectrum where obtained from "Agilent Technologies Cary Eclipse Fluorescence Spectrophotometer (Malaysia)".
is the wave length of the "incident photon".
Where R is the reflection.

Result and Discussion:-
It is clear from the result obtained as shown in table (1) that the peak of absorption and fluorescence wavelength shows a (Red shift) with increasing concentrationand this agreement with Beer -Lambert law. The "radiative life time" and "fluorescence life time" are increased with increasing in the concentrationof Rhodamine C. The "fluorescence life time" was less than "radiative life time" because of "non radiative" processes.
It is also noted from the table that the value of (FWHM)was reduced due to the increase in the number of molecules that absorb active absorption by increasing the concentration of the dye.
Optical properties of Rhodamine C dye in 1-butanolin diverse concentration are shown in figure (1), (2), wherefigure (1) shows the absorption spectrum; and the internal figure shows the relation between (FWHM) and the absorption intensity with the dye concentration. Figure   Another significant quantity is the optical energy gap (Eg) which estimated by using absorption spectrum of the diverse concentration of dye, and plot photon energy versus (αhυ) 2 [17], as shown in figure (5). This indicates a decrease in energy gap due to molecule distances variation with increasing the concentration.
246 The value of the changingoptical refractive index(n) and optical conductivity is very slight and hardly feels, with increasing concentration, the reasonfor this is polarization of dye molecule [18], as shown in Table (2) and figure (6),(7).

248
The extinction coefficient(k) is used in established the kind of the dye and it is a criterion of the dye content; andalso it is indicate to how strongly a dye to absorb light at fixed wavelength, per molar concentration. Figure (8)illustrates the relation between wavelength and extinction coefficient where their value increases with wavelength and concentration.

Figure (8):-Relation between wavelength and extinction coefficient (K).
The real dielectric constant value is higher than the imaginarydielectric constant. Figure (9), (10) illustrates the relation between wavelength andrealdielectric constant and imaginary dielectric constant respectively,it is seen that the real dielectric constant decrease with decreasing the photon energy.Whileimaginary dielectric constantincreases withwavelength whose value depends on the (k) value.

Conclusions:-
From the resultcheckingof optical propertiesit can be inferred that the quantum efficiency for Rhodamine C in 1-Butanol increased with increasingthe concentration. While (FWHM) and stock shift and radiative emission probabilitydecreased with increasingconcentration. Also the result revealed a decrease in theenergy gapwith increasing the concentrationof dye solution.