It is possible via Lambert- Beer's law, but only if the path length and the concentration are known. Please check Calvert & Pitts, Photochemistry.

According to Adela E. Croce and her valuable answer, please give us the following infos prior to receiving an answer. Are you using a single beam, double beam or diodearray spectrometer? Name of the supplier, Year and have you the output via PC routine purchased from supplier?

Good luck

JRG

Hello Hamidreza,

the absorption coeffizient alfa describes the reduction of the light intensity I:

I(z) = I(0)*exp(-alfa*z) for a certain wavelength.

The extinction coefficient k is the imaginary part of the complex index of refraction N = n - ik.

The relation between alfa and k is alfa = 2*k*w/c.

(omega w is 2*pi*f with frequency f and c the velocity of light).

Frequently, absorption and extinction coefficient are used synonymly. I think, your equipment measures alfa.

With Regard

R. Mitdank

Dear Jean Rene Grezes

I am using a Jenway 67 Series. I assume that it is a double beam spectrophotometer. It has two lamps; one provides UV spectrum and another one for Visible spectrum.

Dear Adela E. Croce,

I looked up the book. Still, I cannot find the correlation.

Dear Hamidreza Moazzeni ,

thank you for the fast answer.

Cited:

Another Hint posted 4 years ago :

The relation between extinction efficiency and extinction coefficient?

Question: 13 answers

• Asked 4 years ago

For small particles like nanoparticles, if i have got the value of extinction coefficient, how to convert it into extiction efficiency? Such like the following formation: extinction coefficient = extinction efficiency * A, which A is referred to the cross section and for a spheral particles can be wrriten as " pi*D^2/4 "?

see please the answers.

Concerning your spectrophotometer:

http://www.jenway.com/product.asp?dsl=299

see the UV-Vis part in manual.

Another Hint:

If you want to reinvestigate or use the results cited in the foreign papers for comparison with your own research (I cite your message) :

Dear All,

In a number of articles, authors report extinction or extinction efficiency versus...

Then search in " materials and methods" where you can read p.e. following sentence:

" The absorbance and emission were performed using a spectrophotometer (commercial name ) (Supplier : xxxxxxxxx) at room temperature.

Another names for absorbance (A) are extinction (E), optical density.

According the kind of research and sample , you can make a comparison.

Can you send for the answerers a picture of your UV-Vis spectrum (jpg or pdf) ?

Such a picture of your research can look p.e like my acridine red spectrum (see joined picture) ( taken with a Shimadzu 2450 in EtOH/Supplier Shimadzu Germany /Output to printer)

Values of the measured sample were plotted (see picture with E (value must be between 0 and 2.0) and spectral transmittance in % )

Thank you in advance.

JRG

Dear Jean Rene Grezes

Many thanks for the useful hints and information.