Cyanogen bands

The spectroscopic data do not permit excluding cyclization reactions to a greater or lesser degree. Why the remaining cyanogen band increases must, however, still be considered unclarified. 

A beautiful example of a band system is provided by the violet cyanogen bands.1 Fig. 10 gives the positions of the null lines and... 

Since cyanogen bands are produced by reaction of carbon with atmospheric nitrogen, it is possible to eliminate the bands by arcing the sample in the absence of nitrogen. Various devices are available for this purpose, with the most common being some variation of the Stall wood jet which is arranged to permit the operation of the arc in an inert gas atmosphere. 

Copper electrodes are sometimes used if copper is not an interferent. Cyanogen bands are eliminated but spectral line sensitivity is also decreased. Graphite electrodes reach higher temperatures than copper electrodes during arcing and thus provide a higher excitation energy. 

Wang et al have made use of the lithium carbonate-graphite buffer together with controlled-atmosphere excitation to devise another method of semiquantitative analysis. An intensity gain of 1.4-3.7 was observed when the sample was arced in an argon-oxygen atmosphere and the cyanogen bands were eliminated. 

Apart from the interferences which may arise from other elements present in the substance to be analysed, some interference may arise from the emission band spectra produced by molecules or molecular fragments present in the flame gases in particular, band spectra due to hydroxyl and cyanogen radicals arise in many flames. Although in AAS these flame signals are modulated (Section 21.9), in practice care should be taken to select an absorption line which does not correspond with the wavelengths due to any molecular bands because of the excessive noise produced by the latter this leads to decreased sensitivity and to poor precision of analysis. 

The use of graphite electrodes is responsible for the observed characteristic emission lines of radicals and organic functional groups (e.g. cyanogen CN bands between 320 and 400 nm) and also for the background continuum they generate. 

The early optical spectrum and airshock from a 500-ton TNT expln has been documented (Ref 22). Spectroscopic analysis has revealed that the expl light was produced largely by impurity radiation from sodium, calcium and cyanogen and by forbidden 02 bands. The expected airshock radiation was not detected, presumably due to poor coupling between the airshock and luminosity front... 

Dichloromethyleneamino Tellurium Pentafluoride2 Equimolar quantities of tellurium chloride pentafluoride and cyanogen chloride are loaded into a 61 Pyrex flask to give a pressure of approximately 1 atm at 20°. This mixture is irradiated for 5 h with an internal low-pressure mercury lamp. The volatile products are distilled under vacuum through a series of traps at — 70°, — 110°, and —196°. The trap at — 70° contained the crude product. A series of photolysis reactions starting with 150.7 g of tellurium chloride pentafluoride yielded 82.3 g crude product that is distilled on a 100-cm spinning-band column at 76 torr yield 59.7 g (32%) b.p. 63-65776 torr. 

McGrath and Morrow " studied the reactions of both 0( D) and 0( P) with cyanogen at room temperature by flash photolysis. The 0( D) was produced by the photolysis of ozone. The reaction was monitored by absorption spectroscopy. At first, they attributed the previously unidentified ultraviolet absorption bands at 3250-3330 A to the fulminate radical (CNO), concluding that the initial step of the reaction was... 

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