ULTRAVIOLET SPECTROSCOPIC TECHNIQUE V2') 



instrumental limitations establishes the value for the remaining products 

 and thereby the technical nMjuirements for all other optical components 

 in the system. 



This treatment has been limited but is intended to indicate the frame- 

 work within which an intelligent choice of a source of radiant energy is 

 made. 



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sz, / 



Fig. 4-1 



PRACTICAL ASPECTS 



The last important group of factors in the choice of a particular source 

 are the practical considerations which include simplicity of construction 

 and operation, ruggedness, useful life, availability, and cost. In the past 

 two decades the commercial availability of many ultraviolet sources 

 together with the power supplies for their operation from domestic mains 

 has increased greatly. Because of the importance of the ready avail- 

 ability of many sources a separate section has been given over to the 

 description of these (see p. 126). 



To avoid repetition of the descriptive data contained in the general 

 references noted earlier in this section, Table 4-1 has been prepared. 

 This table constitutes a summary of the various types of experimental 

 and laboratory commercial light sources which have been found useful in 

 radiation studies in the ultraviolet range of the spectrum. No effort has 

 been made to summarize all the data on the subject, but rather to give 

 leads to the literature on some of the older sources which have certain 

 useful characteristics and to give more detailed data on the more recent 

 developments. The reader is again advised to consult the following 

 references for a detailed description of the older sources of ultraviolet 

 light: Forsythe, 1937; Ellis ct al., 1941; Harrison et al., 1948; and Roller, 

 1952. 



DETECTORS OF ULTRAVIOLET RADIATIONS 



Ultraviolet radiations may be observed by the use of fluorescent 

 screens, or such radiations may be detected and quantitatively measured 

 by means of the thermal, chemical, or electrical effects they produce. 

 Visual detection is of value in instances where qualitative observations are 

 adequate, as in the alignment of optical systems; thermal and photochem- 

 ical effects may be employed to determine absolute quantities of radia- 

 tion; because of their susceptibility to amplification, some photochemical 



