Characteristic absorption peak

The characteristic absorption peaks in the infrared (IR) spectra of the compounds available in the literature during last decade are provided in Table 1 ... 

Amide bond is an effective anchor to connect CNTs to substrate surfaces. Lan et al. [52] covalently assembled shortened multi-walled carbon nanotubes (s-MWNT) on polyelectrolyte films. The shortened MWNT is functionalized with acyl chloride in thionyl chloride (SOCl2) before self-assembling. The FTIR spectrum of self-assem-bled MWNT (SA-MWNT) adsorbed on a CaF2 plate modified with PEI/(PSS/PEI)2 shows two characteristic absorption peaks at 1646cm-1 (amide I bond) and 1524cm-1 (amide II bond) resulting from the amide bond formed between the polyelectrolyte films and s-MWNTs. 

Fig. 2.6 The characteristic absorption peak disappears (a) and the refractive index decreases (b) as the photobleaching energy density increases. The refractive index was measured at the wavelength of 1.55 pm. Reprinted from Ref. 15 with permission. 2008 Institute of Electrical and Electronics Engineers...

Fig. 2.11 Absorption spectrum of a DH6/PMMA thin film after it is exposed to DNT vapor at 65°C for various periods of time. The peak at about 630 nm is the characteristic absorption peak of the chromophore. Reprinted from Ref. 33 with permission. 2008 American Chemical Society...

Infrared analysis shows that the 3-bromothiophene contains about 0.5% of 2-bromothiophene, as measured by 2-bromo-thiophene s characteristic absorption peak at 10.26 /. The traces of this lower-boiling isomer can easily be removed by fractionation through a more efficient column. 

IR spectroscopy is useful for the identification of some of the functional groups in an organic molecule. The technique also provides a fingerprint of the molecule and its comparison with authentic specimen often confirms the structure of that molecule. The IR spectra of AHLs show characteristic absorption peaks at 1780,1710,1650 cm-1 arising from the lactone ring, 3-oxo (when present), and amide carbonyl, respectively [15,16]. 

Figure 4.41 presents the FTIR reflection spectra of ethyl xanthate adsorption on marmatite at different pH. The characteristic absorption peaks 1210, 1108, 1025 cm occurred. It has been reported that the characteristic absorption bands of dixanthogen are 1260, 1240, 1020 and 1105 cm and those bands of zinc xanthate are 1030, 1125 and 1212 cm (Mielezarski, 1986 Leppinen, 1990). It is derived from Fig.4.41 that there may exist the mixture of dixanthogen and zinc xanthate because both distinct peaks of dixanthogen and xanthate salt appeares in Fig. 4.41, which further confirms the results from the UV analysis in Fig. 4.36 and Fig. 4.37. It can also be seen from Fig. 4.41 that the intensity of the IR peaks is strong indicating the stronger adsorption of xanthate on marmatite accounting for its good floatability in weak pH media. When pH increased above 7, only a very weak peak appeared in the spectra indicating very weak or no adsorption of xanthate on marmatite accounting for its very poor floatability in alkaline pH media.

Construction effects The effects of construction were less pronounced than the effects of color. In general, cut pile carpets had larger absorbances across the entire spectrum than did loop pile carpets, but the positions of the characteristic absorption peaks were not affected. As for color, accurate calibration models could be developed on second-derivative spectra as long as sufficient variation in carpet construction was included in the library. 

The loss factor for mayonnaise is very low both at high and low frequencies due to the low amount of salt in water and high value of fat content. Tap water shows its characteristic absorption peak at 18 GHz and a small increasing tail at low frequencies due to the small amount of dissolved ions (deionized water would show no tail). Mustard shows a slightly higher value at 20 GHz than ketchup because of its higher water content and a... 

PP shows characteristic absorption peaks at 8385 cm-1 and 6094 cm-1, which correspond to the second and first overtone of the C-H methyl stretching. As the content of HDPE increases, the intensity of these two peaks decreases and a new C-H methylene peak at 6480 cm-1 appears. It can... 

The complex has a green color with a characteristic absorption peak at 670 nm. ( = 890 M-1 cm.-1). It is paramagnetic (one unpaired electron), and e.p.r. studies indicate the equivalence of the cobalt atoms and delocalization of the odd electron.7 Recent x-ray crystallographic studies 6 have shown that the bridging oxygen atoms are bond angle 118°) and that the 0—0 bond distance is 1.31 A. This is shorter than that normally found in peroxides (1.48 A.) and is close to that found for the superoxide ion in K02. Whereas in the peroxo complex there is a torsion angle of 146° about the O—O bond, the Co—0—O—Co atoms are coplanar in the superoxo complex. 6... 

Many compounds of biological importance do not have a distinct absorption maximum. Nevertheless, their concentrations can be determined if they stoichiometrically promote the formation of another compound that does have a characteristic absorption peak. 

A number of inorganic species also absorb. We have noted that many ions of the transition metals are colored in solution and can thus be determined by spectrophotometric measurement. In addition, a number of other species show characteristic absorption peaks, including nitrite, nitrate, and chromate ions, the oxides of nitrogen, the elemental halogens, and ozone. 

The characteristic absorption peaks observed in the present study, such as v no+ (2264 cm ), V] (1130 cm", NOs symmetric stretch) and V3 (1403 cm, NOs asymmetric stretch), are in excellent accord with the previous IR investigations of NO NOs conducted at atmospheric pressure and at low temperatures [88, 90, 91]. However, additional peaks were observed in... 

Figure 7 shows the transmittance of 3% La, 2% Yb co-doped yttria transparent ceramics. The highest transmittance reaches 75% at about 850 nm for 2mm thick sample. There are absorption peaks at about 950nm, which are the characteristic absorption peaks for Yb ion. 

The UV spectrum of palytoxin, as discussed earlier, shows two characteristic absorption peaks at 233 and 263 nm, contributed by the respective chromophores (Figure 29.4). The ratio of their absorbance (233 versus 263 mn), which is approximately 1.7 [3], is characteristic and indicative of the toxin s presence. The absorptions at either wavelength have been reported to be linearly related to palytoxin concentration in the range of 5-20 pg/mL. However, the disadvantage of this method is its detection limit, as the minimum detectable concentration has been reported to be 5 pg/mL (palytoxin standard in water), while toxicological and physiological effects have been observed with concentrations as low as 0.05-0.1 pg/mL [103], which limits its suitability as a regulatory analysis method. 

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