Ultra violet radiation spectra

It has been shown that acetylene when submitted to a high frequency electric discharge yields some diacetylene 75. The action of ultra-violet radiation of wavelength 2,378-2,100 A on acetylene also produced diacetylene, and Cherton considered that the primary step must be the photodissociation of acetylene to C2H and H. At sufficient pressure the absorption spectrum of acetylene shows a continuous absorption in this region superimposed in the band structure. This gives an upper limit of 121 kcal to D(HC C-H). 

Burning stars, such as those originating from Roman candles or shells (Figure 8.5), emit radiation in the ultra-violet, the visible, near-infrared and mid-infrared regions of the electromagnetic spectrum, as displayed in Figure 8.6. 

Electromagnetic radiation of such high energy falls within the Vacuum ultra-violet (VUV), X-ray and y-ray regions of the spectrum. They are called ionizing radiations and their effects on matter are part of the science of radiation chemistry. 

Aliphatic polyamides (PA) and products on their base are polymers with low stability to ultra-violet irradiation and under the effect of solar radiation they destruct less than in a year [1]. In natural conditions ultra-violet part of solar spectrum with wave-length 290-350 nm is more dangerous for these polymers, though aliphatic PAs in this field have very weak absorption of chromophore amide group [2, 3], That is why while examining the problem of PA phototransformations, unlike other polymers, both possibility of light absorption by impurities and self-absorption should be taken into consideration [4],... 

Studying ultra-violet spectrums of indan derivatives let us make a supposition about their "shield" mechanism, which causes light stabilizing effect, as indan sulphuryl amide additions (as carbazolsulphonamides) absorb radiation in the same wave length interval as cellulose diacetate. 

The energy of the emitted radiation is strongly dependant on the material composition and may be somewhere in the total spectrum from the very ultra violet to the far infra-rad. Not all these wavelengths are suited for imaging, since low noise detection with a photomultiplier has to be possible as well therefore imaging is restricted to those wavelengths which are in the detectable range of the photomultiplier. 

The sun emits thermal radiation with wavelengths primarily in the range from 0.3 x 10 m fo 3 x 10 m. In general, abouf 47% of fhe radiafion from fhe sun (af fhe surface of fhe earfh) falls in the visible spectrum, 46% falls in the infrared specfrum and abouf 8% in the ultra violet spectrum [5]. 

Light in the visible and ultra-violet region of the spectrum can be lethal to bacteria although spores and some viruses such as foot and mouth disease virus and polio virus are quite resistant to sunlight. The sensitivity of micro-organisms, contained in an aerosol, to radiation is also dependent upon the degree of desiccation, the oxygen tension, the particle size and the nature of the spray fluid. Dry disseminated bacteria are also affected by... 

Ultra-violet stabilizer As for light stabilizers, but active in the ultra-violet part of the spectrum, and used especially in outdoor applications to preserve polymers against harmful radiation which would otherwise cause degradation. 

---