Spectra

Spectral Database for Organic Compounds (SDBS)
SDBS includes six different types of spectra for organic compounds: electron impact mass spectrum (EI-MS), Fourier transform infrared spectrum (FT-IR), 1H nuclear magnetic resonance (NMR) spectrum, 13C NMR spectrum, laser Raman spectrum, and electron spin resonance (ESR) spectrum.

SciFinder-n
Click on the Substances tab in the search box, search for your substance, and click on Spectra. SciFinder-n may contain the spectrum you need, or it may only contain a reference to an article containing the spectrum you need. In the latter case, click on the citation in the Notes field to access the full text of the article and obtain the spectrum.

NIST Chemistry WebBook
NIST Chemistry WebBook contains data compiled by NIST under the Standard Reference Data Program. Besides providing thermochemical, thermophysical, and ion energetics data, NIST Chemistry Webbook also provides IR spectrum, THz IR spectrum, mass spectrum and UV/Vis spectrum.

ChemSpider
ChemSpider is a free chemical structure database providing fast text and structure search access to over 30 million structures from hundreds of data sources, including open spectra data.

NMRShiftDB
NMRShiftDB is an NMR database for organic structures and their nuclear magnetic resonance (NMR) spectra. It allows for spectrum prediction (13C, 1H and other nuclei) as well as for searching spectra, structures and other properties.

Reaxys
Under Available Data, click on Spectra to obtain a list of references containing spectra for your compound. Click on Full Text to obtain the article. Note that sometimes the spectrum will be found in the supporting information for the article, not in the main text.

Hundreds of atlases and more specialized books are available in the library. Try narrowing your search by type of spectra or application. The volumes of the Aldrich Library are good general atlases of NMR and IR spectra.