On the basis of different types of experiments, the authors develop implicitly the model of surface-enhanced Raman scattering (SERS) of adsorbates on metal surfaces. The long-range enhancement by resonances of the macroscopic laser and Stokes field is separated quantitatively from the metal electron-mediated resonance Raman effect. The latter mechanism proceeds by increased electron-photon coupling at an atomically rough surface and by temporary charge transfer to orbitals of the adsorbates. This model can account for the chemical specificity and vibrational selectivity of SERS and (partly) for the SERS specificity of the various metals.

https://iopscience.iop.org/article/10.1088/0953-8984/4/5/001/pdf

Surface-enhanced Raman scattering

Vibrational spectra for a single molecule adsorbed on a solid surface have been obtained with a scanning tunneling microscope (STM) Inelastic electron tunneling spectra for an isolated acetylene (C2H2) molecule adsorbed on the copper (100) surface showed an increase in the tunneling conductance at 358 millivolts, resulting from excitation of the C-H stretch mode An isotopic shift to 266 millivolts was observed for deuterated acetylene (C2D2) Vibrational microscopy from spatial imaging of the inelastic tunneling channels yielded additional data to further distinguish and characterize the two isotopes Single-molecule vibrational analysis should lead to better understanding and control of surface chemistry at the atomic level

http://science.sciencemag.org/content/sci/280/5370/1732.full.pdf

Single-Molecule Vibrational Spectroscopy and Microscopy

Information about regional carbon sources and sinks can be derived from variations in observed atmospheric CO2 concentrations via inverse modelling with atmospheric tracer transport models. A consensus has not yet been reached regarding the size and distribution of regional carbon fluxes obtained using this approach, partly owing to the use of several different atmospheric transport models. Here we report estimates of surface-atmosphere CO2 fluxes from an intercomparison of atmospheric CO2 inversion models (the TransCom 3 project), which includes 16 transport models and model variants. We find an uptake of CO2 in the southern extratropical ocean less than that estimated from ocean measurements, a result that is not sensitive to transport models or methodological approaches. We also find a northern land carbon sink that is distributed relatively evenly among the continents of the Northern Hemisphere, but these results show some sensitivity to transport differences among models, especially in how they respond to seasonal terrestrial exchange of CO2. Overall, carbon fluxes integrated over latitudinal zones are strongly constrained by observations in the middle to high latitudes. Further significant constraints to our understanding of regional carbon fluxes will therefore require improvements in transport models and expansion of the CO2 observation network within the tropics.

/pdf/towards-robust-regional-estimates-of-co2-sources-and-sinks-5zu9uccwzd.pdf

Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models.

Polymers for flexible displays: From material selection to device applications

Surface infrared spectroscopy

FT-rairs, eels and leed studies of the adsorption of carbon monoxide on Cu(111)

The adsorption of DCl, CCl4, CFCl3, CF2Cl2 and CF3Cl on thin D2O ice films at 110 K has been studied using reflection–absorption infrared spectroscopy (RAIRS). These compounds interact to varying degrees with the ice surface via the OD bonds dangling into the vacuum. DCI was found to dissociate ionically, evidenced by a strong band attributable to D3O+ and the absence of any absorption band for molecular DCl.

Adsorption of stratospherically important molecules on thin D2O ice films using reflection absorption infrared spectroscopy

The chemisorption of ethene, propene, but-1-ene, cis- and trans-but-2-ene and but-2-yne has been studied on a Pt(111) surface using reflection absorption infrared spectroscopy (RAIRS). The results have been compared with transmission infrared spectra of the alkenes adsorbed on a finely divided impregnated Pt/SiO2 catalyst.On the Pt(111) surface ethene, propene and but-1-ene are adsorbed in the corresponding n-alkylidyne form CH3(CH2)nCPt3(n= 0, 1, 2) at room temperature. The cis- and trans-but-2-enes are adsorbed in the form of but-2-yne bonded to the surface in a di-σ/π fashion, as was confirmed by adsorption of but-2-yne itself.The room-temperature spectra of ethene, propene and but-1-ene on Pt/SiO2 all exhibited prominent absorptions from the n-alkylidyne, but other adsorbed species also contributed to the spectra, considered to be predominantly the appropriate di-σ species PtCH2CH(R)Pt (R = H, CH3, C2H5) together with smaller amounts of the relevant π-complexes. In the case of the cis- and trans-but-2-enes, virtually identical spectra were obtained on Pt/SiO2 but with many of the same prominent features as from but-1-ene. Clearly the finely divided catalyst had sites which led to double-bond isomerization. A smaller proportion of di-σ/π bonded but-2-yne was also present.The infrared spectra proved to be very effective at delineating the similarities and differences between the species chemisorbed on Pt(111) and on the Pt/SiO2 catalyst.

Infrared spectroscopic comparison of the chemisorbed species from ethene, propene, but-1-ene and cis- and trans-but-2-ene on Pt(111) and on a platinum/silica catalyst

Michael A. Chesters

Papers

FT-rairs, eels and leed studies of the adsorption of carbon monoxide on Cu(111)

Adsorption of stratospherically important molecules on thin D2O ice films using reflection absorption infrared spectroscopy

Infrared spectroscopic comparison of the chemisorbed species from ethene, propene, but-1-ene and cis- and trans-but-2-ene on Pt(111) and on a platinum/silica catalyst

The adsorption and reaction of methanol on oxidized copper(111) studied by Fourier transform reflection-absorption infrared spectroscopy

The reflection-absorption infrared spectra of n-alkanes adsorbed on Pt(111)