logging in or signing up Ch 14 Apps of UV-Vis jijir Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 51 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: October 25, 2011 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Ch. 14: Applications of UV/Visible Absorption Spectroscopy: Ch. 14: Applications of UV/Visible Absorption Spectroscopy Quantitative analysis of organic, inorganic compounds in all types of laboratoriesM + hv M* Electronically excited: M + hv M* Electronically excited Relaxation processes M* M + heat M* M + hv 2M* M’ + M’’ Not perceptible, small 10 -14 -10 -11 s Emission of a photon Fluorescence:10 -9 -10 -7 s Phosphorescence:10 -4 -10 -1 s Photochemical reactionAbsorbing electrons: Absorbing electrons Bonding Nonbonding bonding nonbonding Participate directly in bond formation and involve more than one atom Unshared outer electrons localized about atoms such as oxygen, halogens, sulfur and nitrogenSlide 4: n * * Bonding Bonding Nonbonding Antibonding Antibonding 128 nm 150-200 nm 200-700 nm 200-700 nm (1000-10,000) (100-3000) (10-100) Increasing energySolvent effects: Solvent effects n * Transitions shift to shorter ’s in the presence of polar solvents (water and ethanol) n * Blue shifted in polar solvents * Red shifted in polar solventsSlide 6: n * Bathochromic (red shift): lowering of the ground and excited state energy levels Hypsochromic (blue shift): hydrogen bonding with the solvent ( ~ 30 nm, energy of H-bond) n *Chromophore groups: Chromophore groups Excitation Identification and quantification Bonding electrons and Functional groups Absorption: Electronic transitions: Absorption: Electronic transitions , , and n electrons Organic molecules, inorganic ions d and f electrons First and second transition metal series, lanthanide and actinide elements Charge transfer electrons Electron donor and acceptorAbsorption: Organic molecules: Absorption: Organic molecules , , and n electrons Excitation of valence electrons to higher energy levels max > 185 nm Limited # of chromophores Rough identification via functional groups Broad absorption bandsAbsorption: Organic molecules Effect of conjugation: Absorption: Organic molecules Effect of conjugation electrons are delocalized lowers the * orbital energy level ex shifts to longer ’s Absorption of multiple chomophores is additiveAbsorption: Inorganic anions: Absorption: Inorganic anions n * transition Nitrate (313 nm) Carbonate (217 nm)Absorption: Involving d and f electrons: Absorption: Involving d and f electrons Lanthanide and actinide 4 f and 5 f electrons Narrow, well defined, characteristic absorption bands First and second transition metal series 3 d and 4 d electrons Broad absorption bandsAbsorption: Inorganic complexes: Absorption: Inorganic complexes M = metal L = ligand (H 2 O ...) Negative charge of L exerts a repulsive effect on the d orbitals and increases their energy No ligand field Octahedral ligand field d x 2 , d x 2 -y 2 d xy , d xz , d yz ∆ EnergyAbsorption: Inorganic complexes: Absorption: Inorganic complexes M = metal L = ligand (H 2 O ...) Magnitude of ∆ depends on... Charge on the metal ion (M) position of parent element in periodic table Ligand (L) field strength I - < Br - < Cl - < F - < OH - < ... No ligand field Octahedral ligand field d x 2 , d x 2 -y 2 d xy , d xz , d yz ∆ EnergyAbsorption: Charge transfer: Absorption: Charge transfer max > 10,000 Must have an electron donor and electron acceptor Examples Thiocyanate: Fe(III)SCN 3 Fe(III) ( acceptor ) Fe(II) SCN - ( donor )SCN Quinhydrone 1:1 complex of quinone and hydroquinoneQuantitative Analysis: Quantitative Analysis Calibration curve Beer’s law: A = bc Standard Addition Multiple species A’ = 1 bc 1 + 2 bc 2 A’’ = 1 bc 1 + 2 bc 2 X equations for X unknowns Must know identity of all components Spectra must be only slightly overlappingDerivative spectra: Derivative spectra 1 rst or 2 nd derivative Reveals additional spectral details Detect minor spectral features Good for turbid solutions Decreased signal to noiseSlide 18: Absorption spectrum First derivative (x10) Second derivative (x100) You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
Ch 14 Apps of UV-Vis jijir Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 51 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: October 25, 2011 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Ch. 14: Applications of UV/Visible Absorption Spectroscopy: Ch. 14: Applications of UV/Visible Absorption Spectroscopy Quantitative analysis of organic, inorganic compounds in all types of laboratoriesM + hv M* Electronically excited: M + hv M* Electronically excited Relaxation processes M* M + heat M* M + hv 2M* M’ + M’’ Not perceptible, small 10 -14 -10 -11 s Emission of a photon Fluorescence:10 -9 -10 -7 s Phosphorescence:10 -4 -10 -1 s Photochemical reactionAbsorbing electrons: Absorbing electrons Bonding Nonbonding bonding nonbonding Participate directly in bond formation and involve more than one atom Unshared outer electrons localized about atoms such as oxygen, halogens, sulfur and nitrogenSlide 4: n * * Bonding Bonding Nonbonding Antibonding Antibonding 128 nm 150-200 nm 200-700 nm 200-700 nm (1000-10,000) (100-3000) (10-100) Increasing energySolvent effects: Solvent effects n * Transitions shift to shorter ’s in the presence of polar solvents (water and ethanol) n * Blue shifted in polar solvents * Red shifted in polar solventsSlide 6: n * Bathochromic (red shift): lowering of the ground and excited state energy levels Hypsochromic (blue shift): hydrogen bonding with the solvent ( ~ 30 nm, energy of H-bond) n *Chromophore groups: Chromophore groups Excitation Identification and quantification Bonding electrons and Functional groups Absorption: Electronic transitions: Absorption: Electronic transitions , , and n electrons Organic molecules, inorganic ions d and f electrons First and second transition metal series, lanthanide and actinide elements Charge transfer electrons Electron donor and acceptorAbsorption: Organic molecules: Absorption: Organic molecules , , and n electrons Excitation of valence electrons to higher energy levels max > 185 nm Limited # of chromophores Rough identification via functional groups Broad absorption bandsAbsorption: Organic molecules Effect of conjugation: Absorption: Organic molecules Effect of conjugation electrons are delocalized lowers the * orbital energy level ex shifts to longer ’s Absorption of multiple chomophores is additiveAbsorption: Inorganic anions: Absorption: Inorganic anions n * transition Nitrate (313 nm) Carbonate (217 nm)Absorption: Involving d and f electrons: Absorption: Involving d and f electrons Lanthanide and actinide 4 f and 5 f electrons Narrow, well defined, characteristic absorption bands First and second transition metal series 3 d and 4 d electrons Broad absorption bandsAbsorption: Inorganic complexes: Absorption: Inorganic complexes M = metal L = ligand (H 2 O ...) Negative charge of L exerts a repulsive effect on the d orbitals and increases their energy No ligand field Octahedral ligand field d x 2 , d x 2 -y 2 d xy , d xz , d yz ∆ EnergyAbsorption: Inorganic complexes: Absorption: Inorganic complexes M = metal L = ligand (H 2 O ...) Magnitude of ∆ depends on... Charge on the metal ion (M) position of parent element in periodic table Ligand (L) field strength I - < Br - < Cl - < F - < OH - < ... No ligand field Octahedral ligand field d x 2 , d x 2 -y 2 d xy , d xz , d yz ∆ EnergyAbsorption: Charge transfer: Absorption: Charge transfer max > 10,000 Must have an electron donor and electron acceptor Examples Thiocyanate: Fe(III)SCN 3 Fe(III) ( acceptor ) Fe(II) SCN - ( donor )SCN Quinhydrone 1:1 complex of quinone and hydroquinoneQuantitative Analysis: Quantitative Analysis Calibration curve Beer’s law: A = bc Standard Addition Multiple species A’ = 1 bc 1 + 2 bc 2 A’’ = 1 bc 1 + 2 bc 2 X equations for X unknowns Must know identity of all components Spectra must be only slightly overlappingDerivative spectra: Derivative spectra 1 rst or 2 nd derivative Reveals additional spectral details Detect minor spectral features Good for turbid solutions Decreased signal to noiseSlide 18: Absorption spectrum First derivative (x10) Second derivative (x100)