204.1 - Molecular Absorption (film, filter, solid, and solution forms)

204.1 - Molecular Absorption (film, filter, solid, and solution forms) The optical SRMs for spectrophotometry are certified transfer standards that fall into three general categories: transmittance, wavelength, and stray radiant energy; each of which addresses a specific instrumental parameter of an absorption spectrometer that must be in control for accurate optical transmittance measurements. To obtain optimum verification results, each SRM must be used within the specified range of conditions for which it is intended.

SRM 2009a Didymium Wavelength: SRM 2009a is now being supported by Calibration Service (Service No. 38061S). Click here for the NIST Calibrations web site: http://www.nist.gov/calibrations. SRM 2035a is an alternative.

SRM 2065 has been replaced by SRM 2035a.

For further information on filters are available:

SP 260-54 - Certification and Use of Acidic Potassium Dichromate Solutions as an Ultraviolet Absorbance Standard SRM 935 (August 1977).

SP 260-68 - Metal-On- Quartz Filters as a Standard Reference Material for Spectrophotometry SRM 2031 (April 1980).

Also see: Table 204.2 - Optical Properties

PLEASE NOTE: The tables are presented to facilitate comparisons among a family of materials to help customers select the best SRM for their needs. For specific values and uncertainties, the certificate is the only official source.


- Certified values are normal font
- Reference values are italicized
- Values in parentheses are for information only


Detail - Detail    Certificate - Certificate    Report of Investigation - Report of Investigation    MSDS - MSDS    Data Files - Data Files    Questionaire - Questionnaire


  SRM Description Unit Size     Wavelength Range (in nm)
Detail Certificate MSDS 931g
Out of Stock
Liquid Absorbance Filters, UV-VIS set (12)   302 to 678
Detail Certificate MSDS 935a
Now Selling
Potassium Dichromate, UV Absorbance Standard 15 g   235 to 350
Detail Certificate MSDS 1921b
Now Selling
IR Transmission Wavelength (Polystyrene Film) 1 card   3 µm to 18 µm
Detail Certificate MSDS 1935a
Out of Stock
Potassium Dichromate Solution/UV Absorbance Standard set (10)   235, 247, 313, 350
Detail Certificate MSDS Data Files 2031b
Out of Stock
Metal-on-Fused-Silica Neutral Density Filters (250nm-635nm) set (3)   250 to 635
Detail Certificate MSDS 2035a
Now Selling
Ultraviolet-Visible-Near-Infrared Wavelength/Wavenumber Transmission Standard each   334 to 805 and 971 to 1960
Detail Certificate MSDS 2036
Now Selling
Near Infrared Wavelength/Wavenumber Reflection Standard
each   975 to 1946