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Infra-red Spectroscopy: Part-1

Infra-red (IR) spectroscopy is an essential tool in the analysis of molecules of forensic significance. IR can help in unambiguous identification of molecules. Regions of IR-Spectrum
1. Near IR: From 12,820—4000 cm-1
2. Mid-IR: from 4000 cm-I to 400 cm-1
3. Far-IR:  from 400—10 cm-1

For most forensic purposes, the mid-IR region is commonly used for identification purposes.
The Mid-IR region can be further divided into 3 main regions:
(a) from 4000 to 1400 cm-1
(b) from 1400 to 900 cm-1
(c) from 900 to 400 cm-1
Some of the common vibrations associated with the groups in organic molecules are given below.

Spectral Range, (cm-1)
Group
Vibration type3700--3200-OHO-H stretching 3400--3330 -NH2Antisymmetric stretching3300--3250-NH2symmetric stretching3065-3030 C-HaromaticC-H stretching3020-2950C-H3Antisymmetric stretching2960-2910C-H2Antisymmetric stretching2970-2860C-H3Symmetric stretching2860-2840C-H2Symmetric stretching2590-2560SH S-H stretching2600-2350 B-HB-H stretching2450-2275 P-HP-H stre…

Mystery of Rome's Jigsaw Skeleton

Mystery of Rome's jigsaw skeleton Police are hunting a 'bone collector' after the discovery in Rome of a skeleton made from five different bodies
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