Subject: IR halfband widths

From: "Hr. Dr. S. Shapiro" <[email-masked]>
Date: Fri, 13 Feb 1998 09:06:19 +0100

Dear Colleagues;

	I quote from an article published in Spectrochim. Acta 19: 1013 ('63):

	"Band broadening can also result where a complex polyatomic molecule can
exist in different conformational forms.  If the centers of conformational
isomerism are ultimately involved in the normal vibration responsible for
the absorption, it is likely that two separate bands will be resolved, and
many cases of this kind are known.  However, if centers of conformational
isomerism are more remote from the atoms primarily involved in the normal
vibration, the perturbation of the steric change on the band frequency may
be very small, in which case it will only act to broaden the band.  NO
EXAMPLES OF SUCH AN EFFECT HAVE YET BEEN POSITIVELY DEMONSTRATED ...."
(Emphasis by capitalisation added.)

	I would be interested in hearing from anyone who can supply me with
references (any, though the more recent the better) definitively
demonstrating conformational IR band broadening of the type that, as of
1963, still had not been positively demonstrated.

	Thanks in advance to all responders.

Sincerely,

S. Shapiro
[email-masked]