3 Micro-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.
4 การใช้แสงอินฟราเรดวิเคราะห์สิ่งมีชีวิต 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
5 อินฟราเรดสเปกตรัม 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
6 โครงสร้างทุติยภูมิของโปรตีน 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.
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