The rate of recombination of nitrogen atoms in the nitrogen afterglow has been measured in a flow system using NO as a titrant and determining the NO content continuously by mass spectrometer. Above about 3 mm of mercury the reaction is predominantly homogeneous and third order. The rate constant, 5.7×1015 cc2 mole—2 sec—1, is independent of temperature in the interval studied (195–450°K). The rate is reduced by substituting helium or argon for N2 as the third body, the ratios of the third-order rate constants with these third bodies being about the same as those for recombination of iodine and bromine atoms. Below about 3 mm of mercury a pseudo-first-order wall recombination becomes important. The recombination coefficient was found to be 1.6×10—5 on a glass wall that undoubtedly was partly poisoned by water.

The mass spect rum of sulfur vapor has been measu red by evapo ra t in g sulfur from a heated t ube directly in to t he ionization chambe r of a mass sp ectrometer. I ons S;; w it h x ra nging fro m 1 to 8 are obse rved with St most ab unda n t. I sotopc ab undances we re comp uted f rom t he S;-ions. The appearance p otentials of S: and St are respectIvcl.v 8.9 ± 0.2 a nd 8.3 ± 0.2 electron volts. This suggests t hat t he vapor in t he ioni zation chamber is a mixture of molec ules co ntaining S2 a nd S8 and poss ibly other molecules.

P olystyren e was placed in a small t ube furnace and t he d egradation produ cts evapora ted directly into the ioniza tion chamber of a mass sp ect rom eter. At abou t 330 0 C a fairl y complica ted mass spectrum was observed , extending t o about m ass 520. Major features of t he sp ectrum are a ccoun ted for b y a mixture of mon om er, dimer, t rim er, tetramer, and pen t ame r, with th e first t wo by far t he most a bundan t . The nonvolat ile liquid fraction recovered from p yrolysis of polystyrene when heated t o 80 0 C in t he t ube furna ce gave a sp ect rum nearly identical to t he above p y rol ysis spectrum except that t h e st yrene con tribut ion is a bsent. The technique should be applicable to a wide range of poly mers.Studies of the structure of polymers by means of mass spectrometric analysis of dearadation products have b eon described previously [J ,' =' 2,3].1 It has also b ee~ dem?nstrated [4] tha t small samples of a wide vanety of complex materials could be identified by the sam e means. In previous studies, a small sample of the material was pyrolysed in an evacua ted vessel outside the mass spectrometer . Consequ en tly, when the vessel was opened to the mass spec trometer only stabl e products with appreciable vapor pressures at room temperature were observed. Altbough this o. ften simplified the spec trum , it precluded informalOn on larg: r fragmen ts and molecules of possible l1llportance III understanding tho s tru cturc of the polymer and the process of degrada tion. . Thi~ paper is a preliminary r eport on a techniqu e III wblCh vacuum pyroly is of high-molecular-weight compounds occurs inside the mass spec trometer env:lope and the degradat ion products are evaporated d.ll'ectly into the ionization chamber after comparatIvely few collisions wi t h walls and with each other.The instrument used for the pyrolysis experiments wa~ a Nier 60° mass spec trometer [5], using magnetIC sweep and provided with a high-speed r ecorder. !he connection from the sample inlet tub e to the lOll. source was r emoved , and a small furnace was supported directly above the ion source inlet by a 6~mm outside diameter Pyr ex tub e, which also proVId ed communication between the ioniza tion chamber and the furnace interior. Tbe upp er end of this P yrex tube was closed by a copper sample holder stru cture with its thelmojunction lead s. The sample holder proper was an upright cup of a few cubic millime ters capacity extending dO\VIlward from this structure and opeining directly to the P yrex-tube in terior. In the design care was taken to provide a short (approximately 1)f in.) open path from the sample to the ionization chamber. Toward this end a Pt gauze ion repeller was used in the ion source instead of the usual plate.-Aii'7ssential precaution in' analyses of this kind is the avoidance of lubr ica ted or waxed joints that must b e heated to remove or insert samples. In the s tructure used, the leads to th e sample holder and furnace structure extended through a removable 4-contact Kovar seal, which c...

The reactions of active nitrogen with acetylene, ethylene, and propylene have been studied in a flow system using a mass spectrometer to analyze the products continuously. Certain features of the mass spectra of the products can be explained on the basis of cyano radical replacement reactions.

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