際際滷

際際滷Share a Scribd company logo

Molar extinction coefficient

Download as PPTX, PDF
D
Dhruv Sharma

The document discusses measuring the molar extinction coefficient of protoporphyrin IX (PPIX) films deposited on titanium dioxide (TiO2) using different solvents. It defines molar extinction coefficient and how it relates to light absorption.Graphs show extinction coefficient values of 1.49x105 M-1cm-1 for PPIX/TiO2 in DMF, 1.15x105 M-1cm-1 in THF, and 1.26x105 M-1cm-1 in a t-butanol:acetonitrile mix. DMF yielded the highest value. The extinction coefficient determines light harvesting efficiency and dye-sensitized solar cell performance.

1 of 15
Downloaded 203 times
Molar Extinction Coefficient For PPIX/TiO2 film in DMF, THF & tBuOH:ACN(Mix.) Solvent Dhruv Sharma
Importance of Molar Extinction Coefficient ( ) Molar extinction coefficient is a measurement of how strongly a chemical species absorb light at a given wavelength. It is an intrinsic property of chemical species i.e. it depend on chemical composition and chemical structure of material, it independent on concentration. Measuring absorbance is a very fast method for determining the chemical concentration, although the specific chemical species in the solution must be known. Other method of measuring concentration, such as titration can take more time and require additional chemicals. The SI unit of 竜 are m2/mol but in practice they are usually taken as M-1cm-1 . Extinction coefficient allow us for estimation of molar concentration of solution from its measured absorbance.
How to find Molar Extinction Coefficient? Using the equation in an experiment Beer-Lambert Law use to find the Molar extinction coefficient. According to Beer- Lamberts law When a monochromatic light beam pass through the homogeneous solution, light absorb in the solution is directly proportional to the product of concentration and path length. A = or = A/cl Where, I0 is incident light, I is transmit light, is molar extinction coefficient, A represent absorbance, c is concentration, l is path length of light travel in the cuvette.
The simple way to calculate it using the given formula. Define all the variables with a value. Absorbance (A), is a measurement without any units, obtained from a spectrophotometer at a particular wavelength of light. Path length is usually considered to be 1. Concentration of the substance (c) should also be known. Substitute these values in the equation mentioned for epsilon. Using a Graph In a graph, several values of A are plotted on Y axis against a number of concentrations on X axis. The slope of the line will be 竜. Again here path length will be 1. Thus, the slope will give you the molar absorptivity. Calculators are the easiest way to calculate these values.
Application of Molar Extinction Coefficient Molar extinction coefficient is particularly useful in spectroscopy for measuring the concentration of chemical solution. Molar extinction used to find the absorption cross section ( ), relation is given as (了) = (了) . 1000 (cm3L-1) which gives the information of surface coverage ( ) on dye-sensitized solar cell, given as =A(了)/(了) Molar extinction coefficient is the intrinsic property of chemical species, so it use to differentiate between different molecules. It use as a fingure print for molecule. Molar extinction coefficient use to define the range of wavelength where light has its maximum depth of penetration in tissue.
Molar Extinction Coefficient of PPIX in DMF -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 350 400 450 500 550 600 650 Absorbance Wavelength (nm) Absorption Maxima = 405nm
Molar extinction coefficient of PPIX/DMF = 1.49 X 105 M-1cm-1 y = 0.149x R族 = 0.996 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 1 2 3 4 5 6 Absorbance Concentration
Molar Extinction Coefficient of PPIX in THF 了max = 406nm -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 350 400 450 500 550 600 650 ABSORBANCE WAVELENGTH (nm)
Molar extinction coefficient of PPIX/THF = 1.15 X 105 M-1cm-1 y = 0.115x R族 = 0.995 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 1 2 3 4 5 6 ABSORBANNE Concentration (10-6 M)
Molar Extinction Coefficient of PPIX in Mix (tBuOH:ACN) -0.2 -0.1 1E-15 0.1 0.2 0.3 0.4 0.5 0.6 0.7 350 400 450 500 550 600 650 Absorbance Wavelength (nm) 了max = 403nm
y = 0.126x R族 = 0.994 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 1 2 3 4 5 6 Absorbance Concentration Molar extinction coefficient of PPIX/MIX = 1.26 X 105 M-1cm-1
Comparison between PPIX/TiO2 film in DMF, THF and Mix Solvent Soret band Q band PPIX 了 (nm) (M-1cm-1) Q 1 Q2 Q3 Q4 (M-1cm-1) 了 (nm) (M-1cm-1) 了 (nm) (M-1cm-1) 了 (nm) (M-1cm-1) DMF 405 1.49 X 105 1.38 X 104 540 1.08 X 104 575 7.03 X 103 630 4.9 X 103 THF 406 1.15 X 105 1.06 X 104 538 8 X 103 577 4.7 X 103 632 4.1 X 103 MIX 403 1.26 X 105 1.12 X 104 537 9.4 X 103 575 5.6 X 103 628 4 X 103
Dielectric Constant List of Common Solvents Dielectric Constant Dipole Moment
Conclusion It appears that selection of the appropriate solvent plays a role in improving the efficiency of DSSC. PPIX/TiO2 film show high extinction coefficient in DMF, then THF, Mix solvent. Both DMF and THF are polar aprotic solvent, DMF (3.82 D) have high dipole moment then THF (1.75 D) i.e. DMF have high polarity than THF. High extinction coefficient means high absorption cross section, it light absorption property. Surface coverage value depend upon, how the dye attach with TiO2 film, it not depend on extinction coefficient. The light harvesting efficiency primarily governed by molar extinction coefficient of dye. The high molar extinction coefficient sensitizer use to obtain high efficiency with thinner TiO2 films.
Investigation of extinction coefficient ( ) of PPIX/TiO2 film in DMF, THF, Mix solvents. Measure absorbance of PPIX/TiO2 film in DMF, THF, Mix solvent (at 1 X 10-4M) and calculate the surface coverage value in respective solvent (Immersion solvent). Measure absorbance of PPIX/TiO2 film in DMF (1,3,5 X 10-5 M), THF ((1,3,5 X 10-5 M)), Mix solvent ((1,3,5 X 10-5 M)) and calculate the Kadsorption value in respective solvent. Measure absorbance of PPIX/TiO2 in DMF solvent (concentration 1 X 10-4M ) 1hour, 3 hour, 5 hour (Immersion Time). To study the change in light harvesting efficiency (L.H.E) with immersion solvent, immersion time, immersion concentration respectively. To study the change in surface coverage value ( ) with immersion solvent, immersion time, immersion concentration respectively. To study the effect of different solvent to control the aggregation and adsorption kinetics for increase the efficiency of DSSC performance. To make the highly transparent TiO2/PPIX films.. To study the electron injection and charge recombination study by using Steady state and time resolved fluorescence spectroscopy. Scope of Project

More Related Content

Molar extinction coefficient

  • 1. Molar Extinction Coefficient For PPIX/TiO2 film in DMF, THF & tBuOH:ACN(Mix.) Solvent Dhruv Sharma
  • 2. Importance of Molar Extinction Coefficient ( ) Molar extinction coefficient is a measurement of how strongly a chemical species absorb light at a given wavelength. It is an intrinsic property of chemical species i.e. it depend on chemical composition and chemical structure of material, it independent on concentration. Measuring absorbance is a very fast method for determining the chemical concentration, although the specific chemical species in the solution must be known. Other method of measuring concentration, such as titration can take more time and require additional chemicals. The SI unit of 竜 are m2/mol but in practice they are usually taken as M-1cm-1 . Extinction coefficient allow us for estimation of molar concentration of solution from its measured absorbance.
  • 3. How to find Molar Extinction Coefficient? Using the equation in an experiment Beer-Lambert Law use to find the Molar extinction coefficient. According to Beer- Lamberts law When a monochromatic light beam pass through the homogeneous solution, light absorb in the solution is directly proportional to the product of concentration and path length. A = or = A/cl Where, I0 is incident light, I is transmit light, is molar extinction coefficient, A represent absorbance, c is concentration, l is path length of light travel in the cuvette.
  • 4. The simple way to calculate it using the given formula. Define all the variables with a value. Absorbance (A), is a measurement without any units, obtained from a spectrophotometer at a particular wavelength of light. Path length is usually considered to be 1. Concentration of the substance (c) should also be known. Substitute these values in the equation mentioned for epsilon. Using a Graph In a graph, several values of A are plotted on Y axis against a number of concentrations on X axis. The slope of the line will be 竜. Again here path length will be 1. Thus, the slope will give you the molar absorptivity. Calculators are the easiest way to calculate these values.
  • 5. Application of Molar Extinction Coefficient Molar extinction coefficient is particularly useful in spectroscopy for measuring the concentration of chemical solution. Molar extinction used to find the absorption cross section ( ), relation is given as (了) = (了) . 1000 (cm3L-1) which gives the information of surface coverage ( ) on dye-sensitized solar cell, given as =A(了)/(了) Molar extinction coefficient is the intrinsic property of chemical species, so it use to differentiate between different molecules. It use as a fingure print for molecule. Molar extinction coefficient use to define the range of wavelength where light has its maximum depth of penetration in tissue.
  • 6. Molar Extinction Coefficient of PPIX in DMF -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 350 400 450 500 550 600 650 Absorbance Wavelength (nm) Absorption Maxima = 405nm
  • 7. Molar extinction coefficient of PPIX/DMF = 1.49 X 105 M-1cm-1 y = 0.149x R族 = 0.996 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 1 2 3 4 5 6 Absorbance Concentration
  • 8. Molar Extinction Coefficient of PPIX in THF 了max = 406nm -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 350 400 450 500 550 600 650 ABSORBANCE WAVELENGTH (nm)
  • 9. Molar extinction coefficient of PPIX/THF = 1.15 X 105 M-1cm-1 y = 0.115x R族 = 0.995 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 1 2 3 4 5 6 ABSORBANNE Concentration (10-6 M)
  • 10. Molar Extinction Coefficient of PPIX in Mix (tBuOH:ACN) -0.2 -0.1 1E-15 0.1 0.2 0.3 0.4 0.5 0.6 0.7 350 400 450 500 550 600 650 Absorbance Wavelength (nm) 了max = 403nm
  • 11. y = 0.126x R族 = 0.994 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 1 2 3 4 5 6 Absorbance Concentration Molar extinction coefficient of PPIX/MIX = 1.26 X 105 M-1cm-1
  • 12. Comparison between PPIX/TiO2 film in DMF, THF and Mix Solvent Soret band Q band PPIX 了 (nm) (M-1cm-1) Q 1 Q2 Q3 Q4 (M-1cm-1) 了 (nm) (M-1cm-1) 了 (nm) (M-1cm-1) 了 (nm) (M-1cm-1) DMF 405 1.49 X 105 1.38 X 104 540 1.08 X 104 575 7.03 X 103 630 4.9 X 103 THF 406 1.15 X 105 1.06 X 104 538 8 X 103 577 4.7 X 103 632 4.1 X 103 MIX 403 1.26 X 105 1.12 X 104 537 9.4 X 103 575 5.6 X 103 628 4 X 103
  • 13. Dielectric Constant List of Common Solvents Dielectric Constant Dipole Moment
  • 14. Conclusion It appears that selection of the appropriate solvent plays a role in improving the efficiency of DSSC. PPIX/TiO2 film show high extinction coefficient in DMF, then THF, Mix solvent. Both DMF and THF are polar aprotic solvent, DMF (3.82 D) have high dipole moment then THF (1.75 D) i.e. DMF have high polarity than THF. High extinction coefficient means high absorption cross section, it light absorption property. Surface coverage value depend upon, how the dye attach with TiO2 film, it not depend on extinction coefficient. The light harvesting efficiency primarily governed by molar extinction coefficient of dye. The high molar extinction coefficient sensitizer use to obtain high efficiency with thinner TiO2 films.
  • 15. Investigation of extinction coefficient ( ) of PPIX/TiO2 film in DMF, THF, Mix solvents. Measure absorbance of PPIX/TiO2 film in DMF, THF, Mix solvent (at 1 X 10-4M) and calculate the surface coverage value in respective solvent (Immersion solvent). Measure absorbance of PPIX/TiO2 film in DMF (1,3,5 X 10-5 M), THF ((1,3,5 X 10-5 M)), Mix solvent ((1,3,5 X 10-5 M)) and calculate the Kadsorption value in respective solvent. Measure absorbance of PPIX/TiO2 in DMF solvent (concentration 1 X 10-4M ) 1hour, 3 hour, 5 hour (Immersion Time). To study the change in light harvesting efficiency (L.H.E) with immersion solvent, immersion time, immersion concentration respectively. To study the change in surface coverage value ( ) with immersion solvent, immersion time, immersion concentration respectively. To study the effect of different solvent to control the aggregation and adsorption kinetics for increase the efficiency of DSSC performance. To make the highly transparent TiO2/PPIX films.. To study the electron injection and charge recombination study by using Steady state and time resolved fluorescence spectroscopy. Scope of Project