NIST Chemistry WebbookAmong other data, NIST Chemistry Webbook has IR spectra for over 16,000 compounds, mass spectra for over 15,000 compounds, UV/visible spectra for over 400 compounds and electronic and vibrational spectra for over 4000 compounds which may be searched in a variety of ways, displayed and printed. Note that the variety of data available here is growing; well-worth checking for a wide variety of data.
The Webbook may also be searched by keyword, property or
chemical name along with a large number of NIST databases at the
NIST Data Gateway. http://srdata.nist.gov/gateway/.