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SRM 2065 has been replaced by SRM 2035b.

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

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	SRM	Description	Unit Size		Parameter
	931h Now Selling	Liquid Absorbance Standard for Ultraviolet and Visible Spectrophotometry	set (12)		absorbance standard
	935a Out of Stock	Potassium Dichromate (Ultraviolet Absorbance Standard)	15 g		235 to 350
	1921b Now Selling	Infrared Transmission Wavelength/Wavenumber Standard	1 card		3 µm to 18 µm
	1928 Now Selling	Infrared Specular High Reflectance Standard (Nominal Diameter 51 mm)	disk		gold plated copper disk, 9.0 mm thick and 50.8 mm in diameter
	1929 Now Selling	Infrared Specular High Reflectance Standard (Nominal Diameter 25 mm)	disk		gold plated copper disk, 3.0 mm thick and 25.3 mm in diameter
	2031b Out of Stock	Metal-on-Fused-Silica Neutral Density Filters (250nm-635nm)	set (3)		250 nm to 635 nm
	2034 Now Selling	Holmium Oxide Solution Wavelength Standard (240 nm to 650 nm)	Cuvette		250 nm to 650 nm
	2035b Now Selling	Ultraviolet-Visible-Near-Infrared Wavelength/Wavenumber Transmission Standard	each		UV-Vis peak locations between 334 nm and 804 nm NIR band locations between 975 nm and 1945 nm
	2036 Now Selling	Near Infrared Wavelength/Wavenumber Reflection Standard	each		975 nm to 1946 nm
	2082 Now Selling	Pathlength Absorbance Standards for Microliter Volume Spectrophotometers	set of 3 vials		pathlength absorbance