316 



T. V. Shcherbakova 



APPARATUS FOR OBSERVING LUMINESCENT RADIATION 



Observations on the intensity and spectral constitution of the lumines- 

 cent radiation from the driUing fluid were conducted on an apparatus devel- 

 oped by N. 0. Chechik. The apparatus consists of a measuring and a power 

 unit. 



The measuring unit consists of a source of ultra-violet radiation and 

 a photosensitive element placed in a light-tight chamber. 



A UFO^A lamp with a UFS-3 filter, transmitting rays with wavelengths 

 less than 420 m/^ (maximum about 365 mju), is used as the source of ultra 

 violet radiation. In order to ensure constant illumination, the supply to the 

 lamp is stabilized by a baretter. 



^' 



r- 



Fig. 1. Optical scheme of photoelectric luminoscope. 1 — source of ultra-violet 



radiation UF0-4A; 2 — filter UFS-2; 3 — vessel contaiaing fluid; 4 — narrow-band 



filter; 5 — ^prism; 6 — filter; 7 — ^photomultipUer. 



The sample of hquid under investigation is placed in a quartz cell which 

 is put into the chamber so that its bottom is irradiated by ultra-violet rays. 

 The luminescent emission thus excited is detected by the photosensitive 

 element, for which an FEU-19 photomultipher is used (Fig. 1). The photo- 

 multiplier cathode is protected from the ultra-violet radiation by a yellow- 

 green filter, which stops rays with wavelengths less than 420 m^ and trans- 

 mits radiation in the visible region of the spectrum. 



The radiation received by the photomultipher is converted into an electric 

 current, which is amplified by a direct-current amplifier (Fig. 2). 



The direct -current amplifier consists of a bridge, two arms of which are 

 the internal resistances of the anode circuit of the valve L^ and the resis- 

 tances i?oK — i?oq and the two other arms are the anode resistances R 



"-39 



27 



and i?28- The current from the output of the photomultipher varies the 



