Date: Wed Oct 29 13:08:15 2008

Author: Zani, Gerald

Subject: Re: absorption spectra

Post:

Here is a photo of the emission-absorption spectra from High pressure sodium.

http://www.physics.brown.edu/physics/demopages/Demo/modern/demo/7b1011.htm

The broadening of the Na D line is due to Doppler broadening and collision broadening. The absorption line is due to a temperature gradient between the inner walls and the outer walls of the lamp.

- JZ

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On Behalf Of Adolf Cortel
Sent: Wednesday, October 29, 2008 12:56 PM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] absorption spectra

Hi Anthony,
Use a high pressure sodium lamp of the type used in the lightning of
streets; when the lamp is quite warm the black lines corresponding to
the absorption by sodium can be clearly seen. With a good difrraction
grating (Starlab is good enough) the doublet can be observed in the
second order spectrum. I got this information at TAP-L from Dick Berg,
look at his site for more information and pictures.
Kind regards,
Adolf Cortel

IES Pompeu Fabra, Barcelona, Spain

Anthony Lapinski escribió:
> In my high school astronomy class, I will be discussing light and spectra
> soon. I wish to do a lab/activity where students can analyze various light
> sources with a diffraction grating. It is easy to show continuous spectra
> with a candle or light bulb, and emission spectra with gas tubes. I am
> looking for a way to show an absorption spectrum. In the past I had
> students use colored filters to cover an incandescent light bulb. This
> sort of mimics the atmosphere of a star.
>
> Does anyone have other ways to show absorption spectra using simple
> materials?
>
>
>



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