Longer wavelength infrared band

In contrast, the longer wavelength infrared (LWIR) band is desirable for imaging cooler bodies (such as the aircraft itself rather than just the hot engines, which can be masked ) and although LWIR detector materials and missile seekers have been... 

Nitro groups of nitroalkanes can be identified by strong infrared bands at about 1550 cm-1 and 1375 cm-1, whereas the corresponding bands in the spectra of aromatic nitro compounds occur at slightly lower frequencies. A weak n —> n transition occurs in the electronic spectra of nitroalkanes at around 270 nm aromatic nitro compounds, such as nitrobenzene, have extended conjugation and absorb at longer wavelengths ( 330 nm). 

The infrared spectra of chemisorbed molecules are markedly different from those of the unadsorbed states. This is true whether the heat of chemisorption is high or low. Although in some cases, such as ammonia on cracking catalysts, the spectrum of the chemisorbed species may resemble that of the gaseous state, this is an artificial similarity caused by the fact that only a small portion of the spectrum is observed. When longer wavelengths are scanned, differences will be noted. The ultimate experimentally defined criterion of chemisorption is observation of a band due to the bond between the surface and the adsorbed species. 

Fullerenes, fulleranes and buckyonions are expected to present weaker transitions in the optical and near infrared with their number decreasing towards longer wavelengths. These transitions may be responsible for some of the known but unexplained diffuse interstellar bands. It would be very important to obtain high sensitivity, high resolution laboratory spectra of these molecules in the optical and near infrared for a more precise comparison with the very detailed observations of DIBs. 

The visible spectrum of 4 (Table 3) contains a strong band at 396 nm and tails off to longer wavelength with a series of shoulders much like a uranocene. The infrared spectrum of the compound is nearly identical to that of the thorium analog 2a and is consistent with tridentate bonding. We are, however, unable to reproduce the nmr spectrum reported by Marquet-Ellis. 

---