Characterization of Nitrogen Oxides by Vibrational Spectroscopy

Routes of formation and composition of NOx complexes adsorbed on palladium-promoted tungstated zirconia

“…This behavior can be explained by assuming that at high temperatures, reaction (2) shifts to the left. This assumption is supported by the fact that N 2 O 3 is stable at low temperature [53]. The gas phase spectrum recorded at 623 K (Fig.…”

“…The Zr-OH hydroxyls at 3740 and 3693 cm −1 are perturbed giving rise to positive absorption in the region of H-bonded OH groups. The gas phase spectrum obtained in the presence of zirconia contains bands due to N 2 O 4 (ν as (NO) at 1747 cm −1 and ν s (NO) at 1264 cm −1 ) and NO 2 (ν as (NO 2 ) at 1617 cm −1 ) [53]. The weak absorption at 2224 cm −1 belongs to the ν(NN) mode of N 2 O, whereas that at 1876 cm −1 corresponds to the ν(NO) stretching of NO [53].…”

“…The gas phase spectrum obtained in the presence of zirconia contains bands due to N 2 O 4 (ν as (NO) at 1747 cm −1 and ν s (NO) at 1264 cm −1 ) and NO 2 (ν as (NO 2 ) at 1617 cm −1 ) [53]. The weak absorption at 2224 cm −1 belongs to the ν(NN) mode of N 2 O, whereas that at 1876 cm −1 corresponds to the ν(NO) stretching of NO [53]. NO 2 and N 2 O 4 are formed by the reaction of NO with O 2 in the gas phase (2NO + O 2 = 2NO 2 /N 2 O 4 ).…”

Nature, Density, and Catalytic Role of Exposed Species on Dispersed VOx/CrOx/Al2O3 Catalysts

“…Four bands are observed at 1907, 1879, 1788, and 1733 cm -1 that can be assigned to cis-ONNO dimers (OdN-NdO) based their positions. 49,50 The infrared bands for NO dimers on Al 2 O 3 are observed on 3VAl (1.9 V nm -2 ), but their intensities are slightly lower than those on pure Al 2 O 3 . Infrared bands for NO adsorbed on V 5+ appear at 1683 and 1775 cm -1 .…”

Electronic Mechanisms of SERS

“…Figure 13 shows the SERS spectra of 5 different Cu films, deposited at 30 K, annealed at the indicated temperatures, recooled to 30 K and exposed to 5 L NO (nitric oxide) [63]. The 1284 cm −1 and 2228 cm −1 bands are assigned to the N-O and N-N stretch frequency of N 2 O (nitrous oxide) (this molecule has the configuration NNO); the 585 cm −1 structure on [64]. The bands at 2283 cm −1 and 2109 cm −1 can be safely assigned to adsorbed neutral and partially negatively charged N 2 , because these bands were observed after exposing a colddeposited Cu film to N 2 [65].…”