Concerning theIRanalyses,thespectradecompositionalsoled
to 10bands.ThePCAresultsonthereferencecorpusarepresented
on supplementary Figs.s 1sand2s. Thedifferentchemicalfamilies
areseparatedbutwithlessaccuracythanforRaman.However,the
IR resultscanbeconsideredascomplementaryorvalidatingdata,
as theycanensuretheclassification proposedbytheRaman
results orbethekeyissueinthediscriminationofsomefamilies.
Indeed, somematerialsarequitecloseontheRamanscoreplots
but wellseparatedontheIRones,asforexamplethegluesand
frankincenses, orthemasticsandshellacs(supplementary Fig. 2s).