UV-Vis Spectroscopy of Biomolecules Lecture 1 PDF

UV-Vis spectroscopy of biomolecules Introduction spectroscopy Electromagnetic waves Resonance The Lambert Beer Law High concentration and stray photons Chromophores in biological samples Jaume Torres...

UV-Vis spectroscopy of biomolecules Introduction spectroscopy Electromagnetic waves Resonance The Lambert Beer Law High concentration and stray photons Chromophores in biological samples Jaume Torres [email protected] Mobile: 81007063 Spectroscopy studies the interaction of light with matter (atoms and molecules) - made of How does light change after passing through the sample? transformed byI sample been has ? light Spectroscopy in physics and chemistry looks at the output and interprets it in terms of input Output molecular organisation (bond distance, bonds strength, molecular geometry) of any molecule (gases, liquids and solids) I small usually molecules For the biologist, the interest is generally focused on typically biological large molecules (e.g., proteins, nucleic acids) mostly in solution or semi-solids (lipid membranes): concentration determination, structural determination, changes in conformation, detection of molecular interactions, and so on. /presence of molecule  This is what usually happens infrared spectroscopy ~ (same thing) Measure how rotational, vibrational, UV-Visible, NMR… much types of & radiofrea (long wavelength) light is photons used : microwaves & transmitted how much - detector is detected & detector , sample Source of light E photons not absorbed comparing (transmitted) are I initial light detected produce photons posed by lamp count how many The y axis can photors are transmitted now many photons be transmittance for each kind of photors of that particular or absorbance poed by lamp Xv/El waveno has. - been detected freg by    ~ spectrum defector I wo energy wavelengths types of photons emitted by lamp  ↑ time rea for to wave go ⑭ through a distance of I & wavelength (x) is called I T(s) period (T) velocity ↑ - Hz- unit of freqt (v) V = se ↓ V X speed of = T -c. = = X T light that fit in km E = h ~ no of waves can Planck constant wave numbers (cm-1) used to represent type of photons in infrared spectroscopy in sc-axis. What are ‘spectra’? Spectra tell us which waves resonate with our system (and get absorbed by it). The waves (x-axis) can be labeled with the Speaks wave’s energy, wavelength or frequency. The bands in the spectrum tell us where resonance has occurred. The job of the spectroscopist is to explain why. Only when the spectrum can be understood, inferences about the molecule’s properties can be made (size, bond lengths, mass, charges, etc). bands/peaks ↓ ↓ ↓ ↓ Electromagnetic radiation consists of oscillating electric and magnetic fields some photons interact better is sample cred ware) (blue) to bands (maximum absorpt pole => only some X/v/ E/W N interact on sampleE but. 2 waves coincides not others g freys of light