IR band intensity

Fig. 7 Dependence of IR band intensities on H2 partial pressure during ethene hydrogenation catalyzed by Ir4/y-Al203 at 288 K and 760 Torr (40 Torr C2H4, 50-300 Torr H2, and the balance He). The bands at 2990 (diamonds) and 2981 cnr (squares) were chosen to represent di-cr-bonded ethene and that at 1635 cnr (circles) to represent water on the y-AbOs support. These IR bands were chosen as the best ones to minimize error caused by overlap with other bands. The triangles represent the reaction rate expressed as a turnover frequency (TOF), the rate of reaction in units of molecules of ethene converted per Ir atom per second. The data indicate a correlation of the band intensities with the TOF, consistent with the suggestion that the ligands represented by the bands are reaction intermediates (but the data are not sufficient to identify the reaction intermediates) [39]...

The variation of the IR band intensities upon nitrogen incorporation for RF plasma-deposited a-C(N) H films is shown in Figure 26, as reported by Schwan et al. [53], As mentioned before, the intensity of the C—H stretching band decreases upon nitrogen incorporation, at the same time that an increase in the N —H stretching band intensity is observed. This suggests that hydrogen preferentially... 

Absolute i>(CO) IR band intensity measurements and interpretation for a variety of cis W(CO)4LL species... 

Figure 2-7 A diagram for IR calibration (Equation 2-86). The data for each given H20t content is obtained by heating the sample to different temperatures to vary the species concentrations. For a perfect calibration, all the trends would lie on a single straight line. However, there is some scatter. Furthermore, the slope defined by data for one fixed H20t content does not equal that for another. Hence, the calibration results (8523 = 0.168 8452 = 0.166) shown in this diagram have a relative precision of only about 10%, whereas the relative precision of IR band intensity data is about 1%.

Figure 9. Coverage dependence of the surface potential and of the IR band intensity of CO on Cu(lll) compared with Q X and Q X 2 where Q is based on the polarizabilities of the free CO molecule and d = 1.07A. All curves have been normalized to pass through the circled point.

Figure 10. (Top) experimental values (X) of the relative IR band intensity compared with Q2 X , where Q is based on ay = 0.18A3 and d = 1.85A (bottom,) coverage dependence of the dipole coupling shift (experimental points) compared with theoretical shifts for random (S a ) and regular (S a 3/2) distributions, assuming the same values of ay and d, and with at = 2086 cm 1...

Variation of IR band intensity of chemisorbed pyridine. Outgassing temperatures (b)100 °C (c)400 °C. Curve (a) refers to the calcined Rb-offretite crystals used. 

As IR spectroscopy is a secondary method of analysis, the development of quantitative analysis methods requires calibration with a set of standards of known composition, prepared gravimetrically or analysed by a primary chemical method, to establish the relationship between IR band intensities and the compositional variable(s) of interest. Once a calibration has been developed, it can then be used for the prediction of unknowns, provided two general conditions are met i) the spectra of the unknowns are recorded under the same conditions as employed in the calibration step (i.e., same instrumental parameters, identical means of sample handling, etc.) and ii) the composition of the calibration standards is representative of that of the unknowns. 

The Bronsted acid site FT-IR band intensity (at 1491 cm i) directly correlates with the catalytic achvity, and the maximum activity observed for 19 wt% WZ is due to the maximum number of Bronsted acid sites generated by the higher interaction of tungsten(lV) oxide with zirconia. Similar composite materials were studied in the acylation of 2-MN with AAN to selectively give the 1-acetylated product in 50% yield. ... 

It has been reported that at the HF level calculated IR-band intensities often differ from experiment by a factor of over 100 percent, but at the MP2 level are typically within 30 percent ofexperiment [159]. A few calculated (frequencies and intensities) IR... 

As a difference with the silicalite, TS-1 shows a characteristic IR band at 960 cm l. Adsorption of water shifts upwards the 960 cm peak to 970-975 cm l[15]. By increasing the Ti molar fraction in TS-1 from 0 to 0.025 a linear increase of the above mentioned IR band intensity with x was observed [15]. This means that the 960 cm l IR band is in someway related to the presence of lattice titanium. 

Figure 10.7 (a) A plot of log (IR band intensity) for on-top hydrogen versus electrode potential and (b) a plot of log (current density) for the HER versus log (IR band intensity). These plots have been used in the analysis of the HER mechanism (see text). Data recorded for polycrystalline Pt (on the ATR prism) in 0.5 M H2SO.f ( ) or 3 M H2SO.f (o). Reprinted from Ref [15] with permission from Elsevier. 

Crystalline silicon doped with carbon and implanted with hydrogen gave IR bands due to H (2967.4 cm ) and C (911.7, 654.7 cm ) localised modes. Ab initio calculations have been reported of the vibrational wavenumbers of HEBrClF, where E = C, Si or Ge. " IR band intensities for vs and V4 were used to estimate effective bond charges in EH4, where E = C, Si, Ge or Sn. Both experimental IR data and calculations are consistent with C3, symmetry for the CI-.CH4 adduct.2"... 

Fig. 12 Integrated IR band intensities of COl (atop), COb (bridge-bonded), and CO2 during the first anodic scan at Pt(l 11) in 0.1 M HCOOH/0.1 M HCIO4 as function of potential [38].

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