Abstract:On May 3, 2000 Canada lost one of its pre-eminent spectroscopists, Professor Murray Brooker of Memorial University, Newfoundland. Murray grew up in Toronto, obtained his B.Sc. from the University of Toronto in 1963 and his Ontario Teacher Certificate from OISE in 1964. During that period he was to say later that his first love was sports-a love he never lost. After two years of teaching at the secondary school level he enrolled for the Ph.D. at the University of Waterloo and I had the good fortune to become hi… Show more
“…Band E at 1370 cm -1 can be assigned to metal NO 3 - complexes and is found in the Raman and IR spectrum. , In the spectral region around 625 cm -1 , peak G assigned to the Cu−O stretch of Cu 2 O is observed . Band F at 850 cm -1 and band H at 1240 cm -1 are attributed to the bending mode and symmetric stretching of nitrite ions. , The band H persists until −0.45 V and then disappeared at −0.55 V. 9 SER spectra from Cu(poly) + 0.1 M HClO 4 + 0.5 mM HNO 3 (a) and Cu(poly) + 0.1 M HF + 10 mM HNO 2 (b) in Ar atmosphere. The cathodic sweep is shown.…”
Nitrate adsorption and reduction on Cu(100) in acidic solution is studied by electrochemical methods, in situ electrochemical scanning tunneling microscopy (EC-STM), surface enhanced Raman spectroscopy (SERS), and density functional theory (DFT) calculations. Electrochemical results show that reduction of nitrate starts at -0.3 V vs Ag/AgCl and reaches maximum value at -0.58 V. Over the entire potential region interrogated adlayers composed of nitrate, nitrite, or other intermediates are observed by using in situ STM. From the open-circuit potential (OCP) to -0.22 V vs Ag|AgCl, the nitrate ion is dominant and forms a (2 x 2) adlattice on the Cu(100) surface while nitrate forms a dominantly c(2 x 2) structure from -0.25 to -0.36 V. The interconversion between the nitrate and nitrite adlattices is observed. DFT calculations indicate that both nitrate and nitrite are twofold coordinated to the Cu(100) surface.
“…Band E at 1370 cm -1 can be assigned to metal NO 3 - complexes and is found in the Raman and IR spectrum. , In the spectral region around 625 cm -1 , peak G assigned to the Cu−O stretch of Cu 2 O is observed . Band F at 850 cm -1 and band H at 1240 cm -1 are attributed to the bending mode and symmetric stretching of nitrite ions. , The band H persists until −0.45 V and then disappeared at −0.55 V. 9 SER spectra from Cu(poly) + 0.1 M HClO 4 + 0.5 mM HNO 3 (a) and Cu(poly) + 0.1 M HF + 10 mM HNO 2 (b) in Ar atmosphere. The cathodic sweep is shown.…”
Nitrate adsorption and reduction on Cu(100) in acidic solution is studied by electrochemical methods, in situ electrochemical scanning tunneling microscopy (EC-STM), surface enhanced Raman spectroscopy (SERS), and density functional theory (DFT) calculations. Electrochemical results show that reduction of nitrate starts at -0.3 V vs Ag/AgCl and reaches maximum value at -0.58 V. Over the entire potential region interrogated adlayers composed of nitrate, nitrite, or other intermediates are observed by using in situ STM. From the open-circuit potential (OCP) to -0.22 V vs Ag|AgCl, the nitrate ion is dominant and forms a (2 x 2) adlattice on the Cu(100) surface while nitrate forms a dominantly c(2 x 2) structure from -0.25 to -0.36 V. The interconversion between the nitrate and nitrite adlattices is observed. DFT calculations indicate that both nitrate and nitrite are twofold coordinated to the Cu(100) surface.
“…40,41 The unperturbed nitrate ion is a triangular planar species of D 3h symmetry with four fundamentals: 1 (A′ 1 , Raman active at ~1050-1070 cm −1 ), 2 (A″ 2 , only IR active at ~830 cm −1 ), 3 (E′, Raman and IR active at ~1380 cm −1 ), and 4 (E′, Raman and IR active at ~715 cm −1 ). 36,42 The band positions depend somewhat on the cation and the crystal phase, see e.g. experimental data on nitrates.…”
The existing evidence for the nature of the phase diagram for the binary system sodium nitrate-potassium nitrate is reviewed and in particular whether the system is of the continuous solid solution type, as has often been stated in the last 80 years, or whether this system is of the eutectic type as was earlier believed and has again been asserted recently. Additional evidence from Raman spectroscopy and Raman mapping on the 50 : 50 mol%(minimum melting point) composition is now presented, supporting the eutectic classification. Abrupt changes in wavenumber, or in the wavenumber-temperature gradient of five Raman bands indicate a solid-state transition at about 115 degrees C and are attributed to a phase transition in KNO(3)-rich areas. On a fast cooled sample, Raman bands attributed to sodium nitrate-rich and potassium nitrate-rich areas were found to persist up to and slightly beyond the melting point, and although their wavenumber-positions converged, the apparent single band could still be resolved into the two bands which could be attributed to the Na-rich and K-rich areas. On cooling, the reverse change took place quickly. Measurements with the initially slow cooled sample, where these areas were bigger, showed that the spectral bands reverted to the room-temperature wavenumber values, after holding at 22 degrees C for only 60-90 min.
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