Question

Question 7 (5 marks) After celebrating her 18th birthday on Caxton St, Miss Terry was drunkenly walking home later at night when she was struck from behind and robbed. A witness saw a man aged in his early twenties running from the scene. The witness could not provide any other information other than the suspect was wearing a red shirt. After close inspection some red fibres were found on Miss Terry's clothing, Four suspects known to the police were arrested and each was found to have a red shirt. Samples of cloth from each of these items of clothing have been collected Your task is to attempt to match the fibres found on the victim with one of the suspects by using FTIR. (a) Identify absorption bands from 2 characteristic functional groups in each spectrum. (b) By comparing the peaks in the fingerprint region, can you positively match any of the fibres found on the victim to the cloth samples from the suspects? Why?

Answer 1

Fibnes collecbed from the vichm Chanacteistic peak conhespondo to N-H Shonp peak at N 3300 etching freganey cameaponds to eCse-H sthetc 2 2100 Peak at 2900 canes pondo cCse)- seretch Peak at opeaks at 1600 24o I500 cohnesponoh to cre stnebcig Suspect 1 o- Sthetehi Broad peak n 34uoo cotnenpond to cororespondo t 2900 S c-o sthebch connesponda peak N100

Suspect -9 Cm-1 Shonp peak ~3300 oresponds to peak N 3000aeneaponoh t ccsp2)-14 betcn peak 2900 cmY cotresponds to Csp)-4 stmetch 2 Cmr Conrerpond to peak N1600 c:c Stetch Suspect 3 peak ~ 150conneo ponds to 84etch 11 00 cn ontenponds to peak C-o ) From tne Angenprint megion b is cuan trat b Suspect 2's c Loth fi6ne from the matches t with tue fibne t foundl Anom tne vicms cloth In tne TR spectrnm inger print megion eines unigue pouttenn diffenent fam otner Each ompound han an unig ue fingen print pattern Since it matchen ith suspect 2. He is tne nobben.