Spectroscopic method uv part 2 organic mol and np
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This document discusses various spectroscopy techniques used in inorganic chemistry, with a focus on applications of metal nanoparticles and organic ligands. It describes how surface plasmon resonance gives silver nanoparticles their color and how that color depends on particle size. It also outlines several applications of silver nanoparticles in biosensing, antibacterial materials, conductive inks, and optics. The document then discusses estimating the number of atoms and concentration of nanoparticles from absorption measurements before analyzing samples of silver and gold nanoparticles. Finally, it covers electronic transitions in organic molecules, conjugated pi systems, and fluorescence spectroscopy techniques for inorganic analysis.
Spectroscopic method uv part 2 organic mol and np
- 1. Spectroscopy in Inorganic Chemistry UV-VIS Part 2 08/2018
- 5. SPR (Surface Plasmon Resonance) https://www.sigmaaldrich.com/technical-documents/articles/materials- science/nanomaterials/silver-nanoparticles.html The strong interaction of the silver nanoparticles with light occurs because the conduction electrons on the metal surface undergo a collective oscillation when excited by light at specific wavelengths
- 6. Color (absorption maximum) corresponds to particle size. Example: AgNP
- 8. Applications of AgNP Diagnostic Applications: Silver nanoparticles are used in biosensors and numerous assays where the silver nanoparticle materials can be used as biological tags for quantitative detection. Antibacterial Applications: Silver nanoparticles are incorporated in apparel, footwear, paints, wound dressings, appliances, cosmetics, and plastics for their antibacterial properties. Conductive Applications: Silver nanoparticles are used in conductive inks and integrated into composites to enhance thermal and electrical conductivity. Optical Applications: Silver nanoparticles are used to efficiently harvest light and for enhanced optical spectroscopies including metal-enhanced fluorescence (MEF) and surface-enhanced Raman scattering (SERS).
- 9. Analyze these 4 samples of AgNP
- 10. Influence of stabilizer Reduction of AgNO3 by Na-citrate +/- PVP No PVA + PVA https://file.scirp.org/pdf/JMP_2015072215535041.pdf
- 11. Number of atoms in one NP d = diameter of NP = density of the metal M = molar mass of the metal http://scholarcommons.usf.edu/ujmm/vol7/iss1/2/
- 12. Conc. of NP in “solution” Lambert-Beer applied: cf curcumin in DMSO: 5.54 * 104 M-1cm-1
- 13. Gold NP: max = 517 nm => = 1.1 * 10 7 (or 8 !?!)
- 14. Estimation of particle size for AuNP d = diameter of NP 0 = 512 nm L1 = 6.53 L2 = 0.0216 https://pubs.acs.org/doi/pdf/10.1021/ac0702084 {for d > 25 nm)
- 15. Alternative method using Absorption values: Experimental parameters: B1 = 3.00 B2 = 2.20 https://pubs.acs.org/doi/pdf/10.1021/ac0702084
- 17. Normally only 2 types of electronic transitions:
- 18. Which transitions are possible for Formaldehyde ?
- 19. Electronic transition selection rules (1) S = 0 (spin selection) (2) l= ±1 (orbital selection / Laporte rule) There must be a change in orbital symmetry (3) the direct product i,el * j,el transforms like x, y or z http://www.southampton.ac.uk/~pileio/peppesoton/Teaching/Entries/2009 /3/10_Symmetry_and_Molecular_Spectroscopy_- _PG510_files/Lecture_6.pdf 19
- 20. Example Butadiene Ground state: 2 el in Au and 2 el in Bg => product: Au x Au x Bg x Bg = Ag Excited state: Au x Bg x Au x Au = Bu x Ag = Bu Transition Ag -> Bu: product is Bu -> has x/y component => transition allowed 20
- 21. Summary of usual electron transitions http://www.chemguide.co.uk/analysis/uvvisible/theory.html
- 23. More conjugated double bonds cause 1. Redshift 2. Higher peaks
- 26. Ox.no. change on metal Under certain situations, Cu(II) can be reduced to Cu(I), thereby forming a radical as intermediate. This could serve as “radical scavenger”
- 27. Curcumin in CH3CN plus Cu(II) Curcumin in CH3OH plus Cu(II) Curcumin in CH3CN
- 28. SEMICONDUCTORS
- 31. Triplet States
- 32. Flouresence emission always occurs from the LOWEST vibrational excited state BECAUSE: the relaxation process is fast !
- 33. http://micro.magnet.fsu.edu/primer/techniques/fluorescence/fluorescenceintro.html
- 35. We measure the excitation spectrum in order to find out the best wavelength, which we should use for the emission spectrum – example:
- 36. Excitation vs Emission Spectrum
- 37. Advantages • More sensitive when compared to other absorption techniques. Concentrations as low as μg/ml or ng/ml can be determined. (One molecule can emit light many times, but in absorption only one time) • Precision up to 1% can be achieved easily • As both excitation & emission wave lengths are characteristic it is more specific than absorption methods.
- 38. Inorganic Analysis • Is in competition to AAS for metal cations • Especially useful for uranium salts • And for certain anions like (a) cyanide: Absorption at 400 nm, emission at 480 nm 0.2 – 50 ug/L (b) Phosphate: An ion association complex between molybdophosphate and rhodamine B provides the basis for an assay for phosphorous at 0.04 to 0.6 µg. The fluorescence is measured at 575 nm with an excitation at 350 nm, after first extracting excess of the rhodamine with chloroform. (c) Flouride
- 39. The End of Part 1