Finding Chemical Spectra and Spectral Data
Spectra Sources on the Web
There aren't many Web-based spectral libraries that are freely available, sizeable, and of high quality. Most free sites have relatively few spectra compared to commercial fee-based libraries. If you find a spectrum on a free site, evaluate it carefully and consider its source and methodology. These sites are listed alphabetically, with a star 
indicating a particularly useful resource.
- Biological Magnetic Resonance Data Bank
- Quantitative data derived from NMR spectroscopic investigations of biological macromolecules. (Univ. of Wisconsin)
- ChemExper Chemical Directory
- CCD contains IR spectra (via interactive applet) for various compounds. The directory can be searched by registry number, molecular formula, chemical name or synonyms in different languages as well as by physical and chemical characteristics and combinations of those data. The CCD may also be searched by substructure. The data are submitted from various sources and should not be considered critically evaluated.
- ChemGate
- A pay-per-view site offering 700,000 NMR, IR and MS spectra from the Wiley spectral data collections. Searching by structure drawing, name, CAS registry number, or SMILES, and browsing by method or compound class are free. After that, get out your credit card. (Wiley-VCH)
- Combined Chemical Dictionary
- Database containing detailed information and spectral data (but not spectral diagrams) on over 500,000 chemical substances and their derivatives. Includes some selected literature references to original articles.
- NIST Atomic Spectra Database
- The Atomic Spectra Database (ASD) contains data for radiative transitions and energy levels in atoms and atomic ions. Data are included for observed transitions of 99 elements and energy levels of 52 elements. ASD contains data on about 900 spectra from about 1 Angstrom to 200 micrometers, with about 70,000 energy levels and 91,000 lines, 40,000 of which have transition probabilities listed. The most current NIST-evaluated data associated with each transition are integrated under a single listing.
- NIST Chemistry WebBook
- The WebBook contains IR spectra for over 8700 compounds, mass spectra for over 12,600 compounds, electronic / vibrational spectra for over 4100 compounds, UV/VIS spectra for 400 compounds, constants of diatomic molecules (spectroscopic data) for over 600 compounds, and ion energetics data for over 16,000 compounds, etc.
- NIST Molecular Spectra Databases
- Three databases of diatomic, triatomic, and hydrocarbon molecules were originally published as spectral tables in the Journal of Physical and Chemical Reference Data. Each covers primarily the microwave region with some data available for the radio frequency region. Rotational spectral lines for 121 diatomic molecules, 55 triatomic molecules, and 91 hydrocarbons have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty, and reference are given for each transition.
- NMRShiftDB
- Web database for organic structures and their NMR spectra. It allows for spectrum prediction as well as for searching spectra, structures and other properties. It features peer-reviewed submission of datasets by users. Some browser compatibility issues; must have JavaScript and Java VM enabled.
- Properties of Organic Compounds
- Contains spectral data (no diagrams) on about 25,000 important organic substances.
- RRUFF (Raman Spectra of Minerals)
- "The RRUFF Project is creating a complete set of high quality spectral data from well characterized minerals and is developing the technology to share this information with the world. Our collected data sets the standard for mineralogists, geoscientists, gemologists and the general public for the identification of minerals both on earth and for planetary exploration." Entries include photos of the sample, collected data, and measured chemistry in addition to the locality and source. (Univ. of Arizona)
- SciFinder Scholar (Registry)
- [This is not a Web resource.] CAS has added experimental spectra for nearly 500,000 compounds to the Registry database. IR, MS and NMR spectra are from Wiley spectral databases and the Japanese SDSB database.
Search in SciFinder for a specific compound, click on the 
icon to view the full compound record, and then scroll down to "Experimental Properties". Click on a "see spectrum" link and your browser will launch and display the spectrum in a new window.
In addition, CAS has included millions of predicted proton NMR spectra from ACD Labs. These are found under "Calculated Properties" tabs.
(Note: Spectra are currently only viewable in the Windows version of the SciFinder client.)
- SDBS - Spectral Database System
- Large database of organic spectra, with thousands of IR, 1H-NMR, 13C-NMR, mass, and ESR spectra, searchable by name, formula, Registry Number, NMR shifts, and MS peaks. (National Institute of Materials and Chemical Research, Japan)
- Sigma-Aldrich Catalog
- FT-IR/Raman and NMR spectra of most compounds in the catalog are downloadable as PDF files. Search by catalog number, name, formula, CAS registry number. Chemical/physical information, structure image are displayable.
- X-Ray Photoelectron Spectroscopy Database
- The NIST X-ray Photoelectron Spectroscopy (XPS) Database gives easy access to the energies of many photoelectron and Auger-electron spectral lines. Resulting from a critical evaluation of the published literature, the database contains over 19,000 line positions, chemical shifts, doublet splittings, and energy separations of photoelectron and Auger-electron lines. A highly interactive program allows the user to search by element, line type, line energy, and many other variables. Users can easily identify unknown measured lines by matching to previous measurements.
--Polymers and Macromolecules 
--Drugs 
