Re: Wavelength "calibration standards".

"> Kevin Sunley wrote:
 > Hello, I was wondering if anyone could suggest some easily obtainable
 > wavelength "standards" for calibration the wavelength alignment of a
 > recording spectrophotometer.
 >
 > I use the word "standard" in quotation marks, as of course I'm not
 > looking for something as standardized as NIST standards sets, just
 > something (perferably a solution of easily available chemical) that
 > would produce relatively sharp absorption peaks at known wavelengths.
 >
 > Are there already solutions that have been popularized for such
 > wavelength checks?  Availability of the chemical is of great
 > importance, as although I do have limited chemical access, most of
 > the chemicals I have access to are histology stains, and other
 > chemicals associated with microtechnique procedures.
 >
 > All of this is because I've recently picked up an old Varian dual-beam
 > recording spectrophotometer (Model 634S) which was being thrown out
 > from a local university.  It required a small amount of fixing up to
 > get it up and running, and I'd been interested to see if it
 > wavelength calibration is still accurate.
 >
 > Thanks,
 >
 > Kevin

Kevin, the following 'free' program gives a good spectra
visualization, so it maybe a good place to start from.

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"PhotochemCAD is a computer-aided research and teaching
tool for the field of photochemistry.  PhotochemCAD contains
a database of absorption and fluorescence spectra of 125
compounds, including molar absorption coefficients (e) and
fluorescence quantum yields () with original literature references
for each compound.  Molecular structures are displayed upon
viewing the spectra.  Modules are available for performing a
variety of calculations that use absorption and fluorescence data,
including calculation of oscillator strength, transition dipole moments,
natural radiative lifetimes, and Forster energy-transfer rates and yields.
Other modules enable multicomponent analysis calculations, simulations
of fluorescence spectra upon energy transfer among linear arrays of
pigments, calculations of blackbody radiator curves, and display of
Lorentzian and Gaussian peak distributions. The spectra can be
displayed on various scales (l in nm, n in Hz or ), and manipulated
in various ways.  The compounds in the database are predominantly
organic in nature with an emphasis on those that are biologically
relevant and those with absorption in the visible region of the spectrum.
[.....]
This program and database can be used as a research tool in
photochemistry as well as a supplement to a lab or lecture course
in organic chemistry, physical chemistry, or biochemistry."
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For details and download see:

 ftp://jslftp:[EMAIL PROTECTED]/home/jslftp

(or the Web site at Photochemistry and Photobiology)


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