Home work Physical and Theoretical Chemistry IV

- Molecular Spectroscopy -

Discussion  Fr 10.04.2009 at 12:15,  PK 11.2



 

Home work 1. Light absorption and emission
 
 

Exercise 1: 

a) When light of the wavelength 400 nm passes through an absorbing solute at concentration 0,667 mmol L-1 and length 3,5 mm, the transmission is 65,5 per cent. Calculate the molar absorption coefficient of the solute at this wavelength and express the answer in cm2 mol-1.   

b) The molar absorption coefficient of a solute at 4400 nm is 323 L mol-1 cm-1 . When the light at this wavelength passes through a 7,50 mm cell containing the solute, 52,3 per cent of the light is absorbed. What is the solute concentration?

 

Exercise 2: 

A certain molecule fluoresces at 400 nm with a lifetime of 1,0 ns. It also phosphoresces at 500 nm. The ratio of the transition probabilities for stimulated emission of the S* → S to T → S transition calculated at the same incident light intensity is 105. What is the phosphorescence lifetime?

 

Exercise 3:

Starting from the Doppler fluorescence line shift of a molecule moving along the direction Z and the thermal distribution of the molecular velocity projections vz derive the expression for the shape of the detected spectral line which was given at the lecture.  

Hint: the total fluorescence intensity should be normalized by unity.

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