Transmission Windows

Eig. 4. Transmission profile for a siUca-based glass fiber. Region A represents electronic transitions B, the transmission window and C, molecular vibrations. Point LL is the lowest loss observed in an optical fiber. Absorption profiles for (-) OH and ( ) Fe are also shown. See text. 

Standard silica telecommunication fibre exhibits several minima of the attenuation (so-called transmission windows) 0.8, 1.3 and 1.55 pm. Special... 

Materials such as cubic zirconia, diamond and sapphire may be used for transmission windows for special applications. 

Critical other physical properties can be tailored, e.g. T, clearing temperatures, absorption/transmission windows... 

Yoshino, K., J. R. Esmond, A. S.-C. Cheung, D. E. Freeman, and W. H. Parkinson, High Resolution Absorption Cross Sections in the Transmission Window Region of the Schumann-Runge Bands and Herzberg Continuum of 02, Planet. Space Sci.., 40, 185-192... 

Fig. 17. Cross-section of the view cell at the spectroscopic level. The IR beam is directed either through the ATR crystal (bottom, solid lines) or through the transmission windows (upper part, dashed lines). The four mirrors are mounted on a motor-driven mobile attachment (76).

Similar intense bands at approximately the same frequencies are observed when other molecules of comparable proton affinity are adsorbed in HZSM-5 e.g.water [41],dimethylether [38,40,41], acetone and various carboxylic acids [41]. Pelmenschikov et al. [42,43] pointed out that these bands are very similar to the so-called A,B,C triplet of OH bands characteristic of strong molecular hydrogen bonded complexes in liquid or solid phases. The most widely accepted explanation for the A,B,C triplet in hydrogen bonded systems is that due to Claydon and Sheppard [44], who suggested that the A,B,C triplet are in fact pseudobands caused by the superposition onto a very broad single (OH) band of two so-called Evans transmission windows caused by Fermi resonance between the (OH) mode and the first overtones of in-plane ( 2 5(OH) = 2600 cm l) and out of plane ( 2 y(OH) = 1900 cm l) bending... 

In the near future this work will shift to lower and more easily accessible redshifts near z = 2.2 where all the lines of interest, from [O II] A3727 to Ha, fall in near-IR atmospheric transmission windows. Nevertheless, the determination of element abundances from nebular emission lines will remain a time consuming task until multi-object spectrographs... 

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