1. A method of identifying candidate spectra within an unknown spectrum, the method including the steps of: a. obtaining a set of comparison spectra; b. comparing the unknown spectrum to the comparison spectra; c. identifying candidate spectra, each candidate spectrum being one of the comparison spectra having a desired degree of correspondence to the unknown spectrum; d. performing the following substeps one or more times: (1) generating new comparison spectra, each new comparison spectrum including: (a) one of the candidate spectra, and (b) one of the comparison spectra from the set; (2) comparing the unknown spectrum to the new comparison spectra; (3) identifying further candidate spectra, each candidate spectrum being one of the new comparison spectra having a desired degree of correspondence to the unknown spectrum, wherein, when performing substeps (1)-(3) again, the candidate spectra of substep (3) are used as the candidate spectra when generating new comparison spectra in substep (1).