QUESTION: how to determine electromagnetic vibration frequen

Sun May 29, 2011 11:35 pm   

Hi all

I am looking for information about the electromagnetic vibration
frequencies of individual elements and molecules, and how these are
calculated.

Any information about what this would be called (if it has a name) and
references to any websites (college level) and/or books would be
appreciated.

Many thanks in advance,

JJ

Mon May 30, 2011 12:01 am   

JJ <santa_at_temporaryinbox.com> wrote in news:58f58952-81e5-4f16-bcde-
dd008f455d20_at_w36g2000vbi.googlegroups.com:


There are levels of detail. This will get you started

http://en.wikipedia.org/wiki/Molecular_vibration

Molecules can have normal and rotational modes of oscillation, and the
description of such systems is covered very well in classical mechanics
textbooks. Eg, the chapter discussing oscillations in Goldstein's
"Classical Mechanics".

I suggest starting there so you get a feel for what is going on.

>>From there you'll be better primed to study the research literature.

Wed Jun 01, 2011 5:01 am   

On May 29, 6:01 pm, eric gisse <jowr.pi.nos...@gmail.com> wrote:

Hi Eric,

thank you for your reply. How can it be determined whether the
discussion is about vibrations due to heat or vibrations due to
electromagnetic properties?

Thanks again

[[Mod. note -- At some level it doesn't matter -- a molecule's normal
modes (whether classical or quantum-mechanical) are defined independently
of how they're excited.
-- jt]]

Wed Jun 01, 2011 5:01 am   

In article <58f58952-81e5-4f16-bcde-dd008f455d20
@w36g2000vbi.googlegroups.com>, santa_at_temporaryinbox.com says...

Note that not all interaction,
connected to particular EM frequency,
is related to vibration.

Vibration of molecules ( atom do not vibrate )
is mechanical, even if related to EM force.
vibration modes of molecules are modified
by rotation modes, giving complicated set
of frequencies able to interact with.

Vibrations/rotations can change their state
by emitting or absorbing EM radiation of their
vibration frequency ( or close to it ).

You are putting your foots
into deep waters of infrared spectroscopy.

Consider if it is still "within your league".
I am afraid If you ask this way, you can get drowned.

--
Poutnik

Sun Jun 05, 2011 9:58 am   

Hooks law works well with the simpleset systems but prediction of
vibrational frequincies - I am gussing you are doing infarred and
Raman spectrocopies? gets very intense. Group theory, symmetry is
usually invoked. People are still writing papers about this stuff!
High level calulational stuff is making papers all the time. Fact is
however emperical obsrevations are how the tables of functional group
spectorscopy have been collected for the most part. The most comon
stuff I am seeing is people observe the spectra and jazz up a paper
with calulation stuff as support. You can use generalities about bond
strengths and correlate it with observation.NMR is much cleaner in
that regard." Chemical Applications of Group Theory" by Cotton is
generally considered a great starting point. Beware this becomes PhD
dissertation stuff,
JJ
On Tue, 31 May 2011 23:01:36 EDT, JJ <santa_at_temporaryinbox.com> wrote: