Solid samples were run as mulls. Liquids were run neat between two potassium bromide (KBr), sodium chloride (NaCl) or zinc selenide (ZnSe) plates.

The spectra were collected at 4 cm^-1 spectral resolution with adequate signal-averaging time to achieve a 5,000 to 1 ratio in the fingerprint region.

All spectra had a minimum absorbance of 0.5 to achieve the desired signal-to-noise ratio. The maximum absorbance was limited to 1.5 to assure photometric accuracy and proper representation of the strong peaks. The spectra were baseline corrected as necessary and any residual water or CO2 absorptions were removed by spectral subtraction.

A small number of simple gases are represented in the library to illustrate the similarities and differences between the infrared spectra of simple versus complex molecules. Pure gases of known concentrations were measured at room temperature in a 25-cm gas cell (1 meter path length) with KBr windows. The pressure used to measure each sample was adjusted to produce at least one band in the range between 0.6 and 1.5 absorbance units by back-filling with nitrogen to produce a total pressure of 750 torr. An MKS Baratron capacitance manometer was used to measure pressure.

The following information for this collection is available on-line, when known:

	Index number
	Compound name
	Molecular formula
	Molecular weight
	Boiling point
	Melting point
	Flash point
	Density
	Refractive index
	Category name
	Sampling technique
	Aldrich catalog number
	CAS (Chemical Abstracts Services) registry number
	Aldrich volume and page number (Book Ref.)

The Aldrich volume and page number will help you locate the printed spectrum in The Aldrich Library of FT-IR Spectra, Edition II (Sigma-Aldrich Co., 1997). The volume and page number field is in the form:

<volume number>,<page number><spectrum letter>

For example, the spectrum with the location number 1,234B refers to the second (B) spectrum on page 234 of Volume 1.