From Uv-Vis data you find absorption (A) data as a function of wavelength. Using the formula of Beer-Lambert law you can find absorption coefficient (alpha).

A= Alpha*C*l

where c: concentration of your solution

and l is the path length i.e. width of quartz cuvette

The absorption coefficent is caluculated using : a=2.303 A/t

a: absorption coefficient (cm-1)

A: absorbance

t: thickness of sample (cm)

HI Chetan,

There is an other similar question which was previously asked. Below is the link of it.. Hope the discussion of it helps you solve your problem.

Regards,

Sreekanth

https://www.researchgate.net/post/How_do_you_calculate_the_band-gap_of_material_from_a_UV_spectrum

I found this response i hope it matches with your need:

water absorption coefficient = 1/a x M/sqrt time

a = surface area

M = Mass of water absorbed

This calculation is relevant to Properties of Masonry Units.