Subject: CCL:Linear dichroism.

From: "Jens Spanget-Larsen" <[email-masked]>
Date: Thu, 4 Oct 2001 11:58:24 +0100

Ali Rashid:

> Hi, I was wandering if anyone knows of a way to simulate the 
> absorption spectra of a system. What i am interested in is, starting
> from a model of a molecules or molecules packed in a certain way,
> can i then calculate  things like the dichroic ratio and the linear
> dichroism?  Thank you in advance. --

Dear Ali,

In principle, transition energies, oscillator strengths and 
transition moment directions of molecular optical transitions can be 
predicted by quantum chemical calculations (the presence of molecular 
symmetry elements may be of great help in this task). It is then 
possible to predict the dichroic ratio and the linear dichroism of an 
assembly of molecules "packed in a certain way", since the resulting 
absorption probability is proportional to the cosine-squared of the 
angle between the individual moment directions and the electric 
vector of the linearly polarized light. See the volume by Michl and 
Thulstrup:

J. Michl, E. W. Thulstrup: "Spectroscopy with Polarized Light. Solute
Alignment by Photoselection, in Liquid Crystals, Polymers, and
Membranes", VCH Publishers 1986, 1995 (ISBN 1-56081-910-3).

Yours, Jens >--<

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
JENS SPANGET-LARSEN         Office:     +45 4674 2710
Department of Chemistry     Fax:        +45 4674 3011
Roskilde University (RUC)   Cell-Phone: +45 2320 6246
P.O.Box 260                 E-Mail: [email-masked]
DK-4000 Roskilde, Denmark   http://virgil.ruc.dk/~jsl
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-