ABSTRACTS OF TECHNICAL ARTICLES 003 



tlian those of the atomic ions by lAttl volts in He, 0.7+°;^ volt in Ne, 0.7^2;^ 

 \()lt in A, OJlo.'j volt in Kr. These results can he interpreted, we l)elieve, only 

 l>y assumiiiii; that the process of formation of the molecular ions observed in 

 this experiment is, usinj^ helium as an eNami)le, an excitation by electron impact, 

 He + G + K.K. — > He* + e, followed by the collision process, He* + He —' 

 He-i^ + e, where He* stands for a helium atom raised to a hi{2;h-lyin}r excited 

 state. Our results differ from those of Arnot and M'Ewen on helium particu- 

 larly in that they reported the appearance potential low enough to permit meta- 

 stable atoms to form molecular ions. 



The Drift Velocities of Molecular and Atomic Ions in Heli^nn, Neon, 

 and An/on. J. A. IIoun'beck . Phys. Rer., 84, pp. 6ir)-G20, Nov. 15, 

 1951. 



Drift velocity measurements as a function of E/po , the ratio of fiekl strength 

 to normalized gas pressure, are presented for atomic and molecular ions of 

 He, Ne, and A in their respective parent gases. Identification of the molecular 

 ions is based upon the time resolution of the apparatus and the dei)endence of 

 ion concentration on pressure, appUed voltage, and gas purit}'. Extrapolation 

 of the low field measurements to zero field yields mobility values for atomic ions, 

 Mu (He+) = 10.8 cmVvolt sec, mo (Ne+) = 4.4, and mo (A+) = 1.63 in good 

 agreement with theor}': Massey and Mohr compute mo (He+) = 11, and Hol- 

 stein gives mo (Ne+) =4.1 and mo (A+) = 1.64. Drift velocitj^ data at low field 

 for the molecular ions agree within experimental error with data of Tyndall 

 and Powell (He), and Munson and Tyndall (Ne and A), which they assigned 

 to atomic ions. A qualitative description in terms of ion-atom interaction forces 

 is given for the observed field variation of the atomic ion drift velocities up to 

 high£'/po . 



Checking Analogue Computer Solutions. E. Lakatos . Proc. Inst. Radio 

 Engrs., 39, p. 1571, Dec, 1951. 



E.xperimental Heat Contents of SrO, BaO, CaO, BaCO^ and SrCOs at 

 High Temperatures. Dissociation Pressures of BaCOz and SrCOz. J. J. 

 Lander\ J. Am. Chem. Soc, 73, pp. 5794-5797, Dec, 1951. (Mono- 

 graph 1930). 



The high temperature heat contents of SrO, BaO, CaO, BaCOs and SrCOs 

 have been measured using the "drop" method. Values have been obtained for 

 the heats of the transitions of the carbonates. The dissociation pressures of the 

 carbonates have been measured to pressures below 0.1 mm and values calcu- 

 lated for lower pressures from the observed heat contents and observed disso- 

 ciation pressures at higher temperatures. 



Electron-Hole Prodnction in Germanium by Alpha-Particles. K. G. 

 McKay'. Phys. Rev., 84, pp. 829-832, Nov. 15, 1951. 



The number of electron-hole pairs i)roduced in gei'maniinn by alplia-jiarticle 



1 Bell Telephone Laboratories 



