C—H absorption bands

For each alkylated extract, there was an absorption at 1700 cm which was absent in the untreated extract. This absorption may be attributed to esters that form from alkylation of carboxylic acids. This interpretation is consistent with the NMR analysis described below. For each O-alkylated extract, there was an increase in the intensity of the C-H absorption bands at 2800-3000 cm consistent with the introduction of aliphatic carbon. 

Light absorption at specific wavelengths is another principle often employed for the online measurement of gaseous pollutants. For example, the absorption of 03 in the ultraviolet at 254 nm can be used, though this experiences cross sensitivity to S02 and PAHs, and C02 in the infrared at 4.26 pm (2,350 cm-1), which has little cross sensitivity to other gases. The most common C-H absorption bands are in the range of 3.33-3.57 pm (2,800-3,000 cm-1). 

Polluted sea slicks were found to be characterised by variable and often very appreciable lipid content as evidenced by C—H absorption bands at 2950 and 2850 cm (Fig- 6c). Hydrocarbons and highly esterified oils dominated the surface films of water associated with shipping, this type of activity frequently giving rise to very thick (>100 nm) surface films. The surface films studied by Morris (1974) were also very thick, between 5 and 30 accounting easily for his observation that surface films consist... 

The anesthetic procaine (Novocaine) has the formula C13H20N2O2. In the proton NMR spectrum, each pair of triplets at 2.8 and 4.3 ppm has a coupling constant of 6 Hz. The triplet at 1.1 and the quartet at 2.6 ppm have coupling constants of 7 Hz. The IR spectrum was determined in Nujol. The C—H absorption bands of Nujol at about 2920 cm in the IR spectrum obscure the entire C—H stretch region. The carbonyl group appearing at 1669 cm in the IR spectrum has an unusually low frequency. Why ... 

Thus polyethylene homo- and copolymers may be analysed using o-dichlorobenzene solvent at 145°C, with the IR detector set to monitor the C-H absorption band at 3.4 jum. 

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