3Micro-IROur skin emits infrared light, which is why we can be seen in the dark by someone using night vision goggles. In space, IR light maps the dust between stars.
4การใช้แสงอินฟราเรดวิเคราะห์สิ่งมีชีวิต A motion of diatomic molecules as a springStretching vibrationsabsorbance5001000150020002500300035004000Wavenumbers (cm-1)ccHHHHBending vibrations1OHNCHIGHLOW400025002000180016001550650Wavenumber(cm-1)=HHHHwavelength (cm)How does IR detect biologcal sample? Because this sample contain biochemical molecule, which contain various function group.Each chemical bond in a molecule will absorb IR energy, then vibrates at a frequency which is characteristic of that bond.A group of atoms in a molecule (e.g. CH2) may have multiple modes of oscillation caused by the stretching and bending motions of the group as a whole. If an oscillation leads to a change in dipole in the molecule, then it will absorb a photon which has the same frequency.In chemical analysis, IR spectrum will show as wave number which correlate to wave lengthcc
5อินฟราเรดสเปกตรัม C C H H H H 1650 cm-1 (N–H) bending (C=O) stretching Biomedical samples comprise a mixture of proteins, nucleic acids, lipids and carbohydrates, and this complexity is reflected in the IR absorption spectra they produce.The amide I band at around 1650 cm-1 which results principally from the (C=O) stretching vibrations of protein amide bonds;The amide II band close to 1549 cm-1 resulting from a combination of the (N–H) bending and (C–N) stretching vibrations of the amide bonds;the (C=O) stretching of lipids at about 1740 cm-1; and the antisymmetric nas(PO2) stretching of nucleic acids and phospholipids near 1225 cm1.Many biological samples have highly specific vibrational signatures that form a database for discriminating various states
6โครงสร้างทุติยภูมิของโปรตีน random coil - helix - sheetThis amide I band composes of 80% from the C=O stretching vibration of the amide group, coupled to the in-plan N-H bending and C-N stretchingamide I band consists of a series of overlapped component bands which occurs as a result of the secondary structures present in proteins.