Spatial Resolution Microspectroscopy the ability to view two closely spaced points as distinct objects Diffraction the bending (or scattering ) of light/energy by an opening of an optical element (lens, aperture)
IR Microspectroscopy Sampling Modes Transmission Reflection
IR Microspectroscopy Sampling Modes Transmission Secondary mirror Reflection Primary mirror
IR Microspectroscopy Sampling Modes Transmission transparent samples, thin layers Reflection ATR reflection - absorption, specular reflection, grazing angle
IR Microspectroscopy Sampling Modes Reflection - ATR simplifies sample preparation simplifies sample thickness problem (0.4-2.0 μm penetration depth) View Mode position sample on stage adjust for contact alert contact sensor IR Mode
IR Microspectroscopy Sampling Modes
IR Microspectroscopy Sampling Modes Reflection grazing angle View Collect
Fig. 5. A) Photomicrograph of pressed fragment of sample BMM035 from Cave N(a), Bamiyan, showing a multi-layered structure: 1 = yellowish transparent layer, 2 = green layer, 3 = black layer, 4 = white ground, 5 = transparent brownish layer, and earthen rendering. B) Chemical mappings obtained by SR-μFTIR, showing the distribution of three particular ingredients: in red, proteins; in green, carboxylates; in blue, hydrocerussite. Map size: 190 170 μm 2 ; step size: 10 10 μm 2. C) Average FTIR spectra obtained in the green layer (#2), the white ground layer (#4) and the transparent brownish layer (#5). The gray rectangles highlight the vibrational bands used to generate chemical mappings displayed in B). FTIR mikrospektroskopie synchrotronové záření
FTIR mikrospektroskopie srovnání s dalšími metodami
Povrchová vibrační spektrometrie Pavel Matějka
Povrchová vibrační spektrometrie 1. Povrchem zesílená Ramanova spektroskopie - SERS 1. Princip metody 2. SERS subtráty 3. Interpretace dat 2. Povrchem zesílená infračervená spektroskopie - SEIRA 1. Princip metody a instrumentace 2. Interpretace dat 3. Infračervená reflexně absorpční spektroskopie - IRRAS 1. Princip metody a instrumentace 2. Interpretace dat
Povrchová vibrační spektrometrie
Úvod k vibrační spektroskopii svrchní tón - overton fundametální přechod fundametální přechod 13
SERS 70. léta objev povrchem zesíleného Ramanova rozptylu (SERS) A new field is born, apparently in full adulthood, and complete with a name. Such was the case with the Mössbauer effect and with polywater, and so, too, was the case with SERS. The first resulted in Nobel Prize, the second was shown to be spurious; SERS, I believe, has settled in the territory between. Martin Moskovits
SERS 70. léta objev povrchem zesíleného Ramanova rozptylu (SERS) Fleischmann M., Hendra P.J., McQuillan A.J.; Chem. Phys. Lett. 26, (1974) 163. - pozorování velmi intenzivního spektra pyridinu na stříbrné elektrodě vysvětleno nárůstem plochy povrchu elektrody po jejím zdrsnění Fleischmann Martin - nar. 29.3. 1927 - Karlovy Vary - od 1938 v Anglii - 1973-74 - prezident - the International Society of Electrochemistry
A schematic representation of a SERS experiment with pyridine adsorbed on silver, showing the incident laser and Raman scattered light, the intensities of which are both influenced by the enhanced field at the silver surface resulting from surface plasmon excitations. 2009 by The Royal Society McQuillan A J Notes Rec. R. Soc. 2009;63:105-109
SERS surface enhanced povrchem zesílený zesílený signál od specií adsorbovaných na povrchu stříbra, zlata a mědi faktor zesílení více než 10 4 (lokálně i více než 10 12 ) - až k detekci jednotlivých molekul zesílení závisí na morfologii povrchu hrubý (nerovný) povrch nanostrukturovaný, nanočástice p E dva mechanismy elektromagnetický (povrchová plasmonová resonance), chemický chemisorpce, komplexy s přenosem náboje ( molekulární resonance), sorpce barevných látek SERRS SERS-aktivní substráty zdrsněné elektrody, koloidní částice, ostrůvkové filmy, mezifázové filmy
SERS Elektromagnetický mechanismus vybuzení lokalizovaného povrchového plasmonu (plasmon-polaritonu) zesílení závisí na morfologii povrchu hrubý, (nerovný) povrch nanostrukturovaný, nanočástice Modely koule, elipsoid řada (dotýkajících se) koulí dvojice koulí s proměnlivou vzájemnou vzdáleností
SERS Chemický mechanismus vybuzení molekulového rezonančního Ramanova rozptylu pro povrchový komplex přenos náboje mezi adsorbátem a povrchem kovu Modely HOMO LUMO analogická koordinační sloučenina zahrnutí několika atomů (nabitého) klastru vliv povrchového potenciálu
SERS giant enhancement of Raman signal two mechanisms involved electromagnetic - long range, depends on metal-substrate properties (surface plasmons are involved) coin metals Au, Ag, Cu chemical - local, molecular structure plays an important role (formation of surface complex)) 20 Electromagnetic Excitation of surface free electrons of the metal plasma oscillation Surface-plasmon resonance SERS effect Chemical Excitation of charge-transfer transition of surface-complex species Molecular resonance
SEIRA Spectroscopy less enhanced signal than in the case of SERS - up to three orders of magnitude two mechanisms proposed electromagnetic - long range, depends on metal-substrate properties chemical - local, molecular structure plays an important role
SEIRA Spectroscopy The first report about surface-enhanced infrared absorption was published by Hartstein et al. in 1980 The study was entitled Enhancement of the infrared absorption from molecular monolayers with thin metal overlayers The experiment was carried out using p-nitrobenzoic acid (PNBA) and recorded with attenuated total reflectance (ATR) technique Nevertheless, the presented results correspond to some aliphatic impurity, not to PNBA. However, the intensity of bands increased steadily with the thickness of silver overlayer, from 0 to 6 nm. The largest enhancement factor was about 20.
SEIRA Spectroscopy The first report about surface-enhanced infrared absorption was published by Hartstein et al. in 1980
SEIRA Spectroscopy isolated spheroids 90 x 30 nm
The complement of surface Raman spectroscopy, with vibrations showing a dipole moment change prependicular to the surface being reinforced and enhanced advantages: a wealth of molecular information on the level of a single chemical bond
Infrared spectroscopy on membrane proteins. Jiang X et al. PNAS 2008;105:12113-12117 2008 by National Academy of Sciences
Advantages: extremely high sensitivity narrow spectral bands inherent molecular specificity of unlabeled targets opens interesting opportunities for large biomolecules sensitivity and selectivity for similarly structured molecules Advantages SERS uses as a read-out method spectrum shows very specific and narrow Raman lines minimizing the spectroscopic overlap of different labels not sensitive to any quenching process or photobleaching