Explanation of Time-Lag method to find out diffusion co-efficient in gas permeance properties.
Proper explanation of the above is earnestly required.
The is usually carried out with a corrleogram - an exponential decay curve obtained by storing (signal) information and comparing the obtained signal against another signal or against itself. The correlogram is a way of relating the change of information over time. The quicker the information is lost then the quicker is the lag time (i.e. the information is 'similar' for a shorter period of time). This corresponds to the faster moving particles or molecules. If the particles or molecules are larger then the rate of loss of information (i.e. the signal is closer to what it's compared against) is slower and the time lag is therefore longer. See attached plot. The diffusion coefficient is obtained via this time lag and can then be related to the size of the diffusing species by the simple Stokes-Einstein law.
Thank you Sir for extending such an elaboration.
I have a request can you send me any reference paper too, were i can get some equations too.
Look at slides 20 onwards (and 27/28) in: http://nanoparticles.org/pdf/nobbmann.pdf
There are more Greek letters than an Athens post office in this document. "If you seek equations, then you will find them"
Research Roy Pike and his (team's) paper in Nature in 1970. You'll find the logic for why the correlogram decay is exponential. Nature 227, 242 - 245 (18 July 1970); doi:10.1038/227242a0 "Determination of Diffusion Coefficients of Haemocyanin at Low Concentration by Intensity Fluctuation Spectroscopy of Scattered Laser Light"
To study the transport property in membrane (i.e., Solution Diffusion model), i got an equation to find Diffusion co-efficients (D) by Time-Lag method
D=(l^2)/6theta; theta=time lag; l= thickness of membrane
now i have thickness of membrane but theta i cannot calculate.
The equation i got from the slide you sent (i.e., Stokes-Einstein eq.), how much i can apply it for my work i am not understanding, cause hydrodynamic diameter is not available with me.
Please help me Sir.
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