Photosynthesis in the Shortest Ultraviolet 137 



also allows a direct observation of their further reactions, which is very important 

 for disentangUng the complicated path from the primary radicals to the stable 

 final products. We studied recently with the aid of this method the reaction of 

 the excited amino radical (NH2*) with methane by observing the quenching 

 of its luminescence. 



When a mixture of gases is present, there is in principle the possibility to 

 activate only one component by light, for example the one possessing its threshold 

 at the longest wavelength, e.g. ammonia, not affecting the others. In general, 

 however, the radiation used activates more or less all the components of the gas 

 mixture. 



The strong monochromatic radiation of the xenon lamp (at 1295 Â) permitted 

 Groth to activate the carbon monoxide molecules in mixtures with hydrogen 



col III i i 



cH4ir~^i:3 



C+O - CO2 CO* 



CH^+H >" Hp»CpH^,CpH^, CgHp 

 od s 



H + OH' H + OH ^-H2,02,H202 



ads 



NHai 



NH2 + H -^N2,H2,N2H4 



10 



1200 



1 \ r 

 9 



1400 

 1295 1470 



Xe Xe 



1 \ \ I ] 1 1 — 



3 7 6 5eV 



1650 1850 2000 2537 Â 



Fig. I. Spectral ranges of photochemical sensitivity for gases 



and methane [5]. In the last case however methane was also activated [6]. The 

 final products in these cases, according to Groth, were : 



CO + H2 > CO2, H2O, H2O2, H2CO, (HC0)2 



CO + CH4 > H2CO, (HC0)2, aldehydes, H2 



Formaldehyde, glyoxal and other aldehydes are thus the products of photo- 

 synthesis from simple stable gases under the action of the shortest ultraviolet 

 radiation. The quantum yield for the aldehydes from CO + CH4 is about o-i. 

 Formaldehyde can also be produced by the action of the same shortest radiation 

 upon a mixture of gaseous water with carbon dioxide [7]. 



Formamide can be obtained by the action of the ordinary short ultraviolet radia- 

 tion (A > 1850 Â) on a mixture of anmionia and carbon monoxide [8], only 

 the former being activated, according to Fig. i. 



It must be mentioned that, although nitrogen is regarded as photochemically 

 inert in this spectral range, since it is dissociated at much shorter wavelengths 

 than the Schumann range, nevertheless metastable nitrogen molecules are here 

 produced, as has been recently proved by Soviet scientists. They have observed 

 in nitrogen irradiated by wavelengths in the Schumann range the emission of 



