Near-IR wavelengths

Recently, by using improved nanosecond pulse radiolysis with the monitoring wavelength region from 300 to 1600 nm [44], absorption spectra due to main reactive intermediates such as the intramolecular dimer cation radical in the near-IR wavelength region were clearly observed in the pulse radiolysis of polystyrene in various solutions [47]. For example. Fig. 1 shows the absorption spectra observed in the pulse radiolysis of polystyrene solutions in CH2CI2. 

Optical Transparency of Fluorinated Polyimides at Near-IR Wavelengths... 

Because many compounds of biological interest absorb light in the UV, visible, and/or near-IR wavelengths, spectrophotometry can be a very useful technique in identifying unknown compounds. When given a sample of a pure compound, an ab-... 

In the 1980s, the discovery of spectral windows allowed Earth-based IR observations of the subcloud atmosphere on Venus nightside (Allen and Crawford, 1984). High-resolution IR spectroscopy in these windows led to the discovery of carbonyl sulfide (OCS) and the first measurements of HCl and HF below the clouds (Bezard et al., 1990). The Galileo and CASSINI flybys of Venus (see Table 1) utilized these spectral windows to image the surface at near IR wavelengths. 

The photodecomposition of AgNa with UV light (X < 365 nm) leads to absorption bands in the visible region that have been identified as colloidal metal centers [91,97] (Section D). Photoconductivity accompanied the decomposition, and after about 0.1% decomposition such that colloidal centers have formed, photoconductivity was also observed in the visible and near-IR wavelengths [236]. AgNa is considered an ionic conductor in which mobile interstitial cations predominate. 

A similar two-step process, i.e., HP followed by HIP, has been used to prepare optically transparent poly crystalline spinel ceramics [193, 195]. The elfect of HP temperature on optical properties of the final ceramics HIP sintered at 1900 °C for 1 h under a pressure of 189 MPa was studied. Three HP temperatures, 1400, 1450, and 1500 °C in vacuum of 10 Pa for 1 h at 50 MPa, were examined. The sample HP pre-sintered at 1400 °C had the maximum transmittance of over 60 and 70 % in the UV-visible and near-IR wavelength regions, respectively. The light transmittance was well correlated with the microcracked grain boundary surface area per unit volume of the samples. 

Fig. 5.22. Comparison of response at visible and near IR wavelengths of best classical and NEA InGaAsP photoemitters [S.124]...

Since the absorption band strength decreases about one order of magnitude with each increase in the order of harmonics (i.e., the vibrational quantum number), the losses at visible and near-IR wavelengths can be appreciably reduced by substituting deuterium or fluorine for hydrogen atoms. Kaino etal have produced low-loss optical fibers at visible wavelengths from deuterated... 

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