Plasma chemistry in electrical discharges - ACS Publications

e.g., open k e n t e r 2-electron band and t,he closed 3-center 2-eleclron bond as in t,he. Lipscomb bonding thoories for t,he boron hydrides. No atte...
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properties of this fundamentally distinct state of matter, and t o the realization t h a t electrical discharges provide a convenient method for the laboratory synthesis of evidenre agrees, e.g., icosohedral UnHnZ-, unusual compounds and the preparation the stroct,ore is stated unequivocally. of free radicals. As the first book in Others, less certain, m e p~.esented as a English in thirty years devoted specifically "highly probable stroctnre," with occat o this subject, Dr. McTaggart's work is sional alternatives discussed. Qnalitative most welcome. expositions of the bonding theories for I n spite of its general title, this work is electron-deficient compounds are given, almost exclusively concerned with lowe.g., open k e n t e r 2-electron band and t,he pressure, "cold" plasmas, which can he closed 3-center 2-eleclron bond as in t,he produced by low-power, laboratory-scale Lipscomb bonding thoories for t,he boron apparatus. The first two chapters pprehydrides. No attempt is made t o consent a brief history uf plasma research and sider quantitatively the extrapolat,ion to a. qualitative descripbiun of t h e properties the addit,ionsl sophistication of higher of the chemical species within electrical multi-center bonds. Excellent discussions discharges. Included are references t o are presented, very well illustrated, of earlier texts and descriptions of the older possible mechanism of stereochemical t,echnical terms. Chapters 3 and 4 derearrangements, e.g., sqllRre alltiyrism scribe laborat,ory devices for the generation into dodecahedron, ete. I t is refreshing of plasmas. Emphasis is placed on to see public admission t h a t the qnantitamodern radiofrequency and microwave tive relationship between structure and apparatus. Chapter 5 is an excellent retheory lacks a rigorom theoretical basis a t view of the techniques used t o investigate present. atomic and free radical conceut,rations in Chapter 4 presents a general piet~lreof discharges. The largest portion of the the react,ivity of the class of compounds, book, Chapters 6 through 9, describe the thermal stability, hydrolytic stability, etc. I t is amssing t o find t h a t CSPB~~FIL*reactions of dissociated hydrogen, oxygen, nitrogen, and halogens. Nmphnsis is is stable in vacua a t 810" and that the placed an the kinetics of atomic species R , 2 H , ~ 1ion is stable in strong aqueous extracted from the plasma. The mt,hor is base or acid, and can even be coriverled selective in his choice of material and (in solution) t o the dibasic acid, II&lHn, critically reviewu most of the recent pubwith pZC E H1S04. On the other hand lished literature. exosubsbituted polyhedral chemistry is extensive, e.g., carborylio acids, diaaoninm The lasl thl.ee chapters briefly discuss salts, k e t o ~ e s ,mercsptans, nitriles, etc. the reactions of simple organic radicals, I t is reporled that compounds containing synthesis of covdent hydrides and halides, s,htit,ntion of boron by carbon, snlfw, and the dissacintian of ga.seo,~s oxides. and phasphorw have been prepared. As These sections are each qnile short. The well, irou, cobalt, and nirkel form eomplexes with severs1 polyhedra, in which the mot$ atom oceupiss n vwtex in one or more borane polyhedra. to tho ~eact,ionsof aramat,ic ~pecies or Chapters 3 and 6 are used io describe polymeria~tionst~ldies. the synthesis and chemical pl.operties of A mnmber of minor criticisms can be the eut,ire class of compounds. Chapter 7 offered. I n his discussion of apparatos, int,roduces the uome~~elalore, whieh is a. t,echnical jargon is ovenlsed. The survey bit confusing, but apparently not, settled of deactivation of excited species omits a as yet. Chapter 8 was sn nfterthooghl major process in laboratory plasmas, amw d simply adds 2 pages of reccut developbipolar diffnsion. S e v e ~ d unlikely rcmonts. I t is suspected that il was obsoact.ion mechanisms are presented without lete before the type was set. reference t o the original papers. Several The anthors have presented a s~tperb sections of bhe text appear misplaced, sneh small monograph h y meaw of whieh the as the discussion of activation energy of matwe chemist or even a 3rd or 4th year the graphite-oxygen sysiem lisbed wider "miscellaneous t o p i d ' rat,her than oxygen ~mdergradoato call ohtnin a very clear chemistry. IIowwer, (Ire overall quality pietnre of (as well ns iutrodnction to) R of this book is quite high. Dr. McTaggsrt fascinntiug new field of chemistry. I t has succeeded ill bringing together a large is all outstnndil~gexample of the truly high q d i t y which is chamcleriatic of RIuctlerbody of disconnected literature in a coherties' p ~ ~ b l i e s t i o ~ , ~ . ent and highly readable manner. The relationship of electronics and physics lo S. Y. TYREE,JR. plasma chemistry is made clear, and the College of William and Man1 reader is alerted t o the special problems, VirilIiamsbarg, Virginia s m h a3 the meaning of temperature, which have created diffiadty for plasma chemists. Plasma Chemistry in This work cannot be considered as Electrical Discharges either a textbook or a comprehensive t,reatise, but rather a monograph reflecting F . K . Mel'aggarl, llivisiorr of Mineral the author's own field of research: reChemistry, C.S.I.R.O., Melbourne, actions of simple inorganio molecules Australia. Elsevier l'ublishi~rg Co., within and extract,ed from noll-eauilibrium Amst,erdam, New York, 1967. xi 246 pp. Figs. and tables. 14 X 21.5 om. $17.50. ~

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Research related t o the chemistry of partially ionmed gases is rapidly increasing. This is due both t o an interest in the

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lourno1 o f Chemiml Education

ist who wishes t o become acquainted with current basic research in this interdisciplinary field. The clarity of presentation suggests t,hat this book would be stimulatine to senior undereraduate students wish-

proposed reactron mechanisms of considerable interest. I n addition, this book can be highly recommended to the ehem-

CHESTERE. GLEIT Norlh Carolina Slale Uniuersily Raleigh

The Application of Plasmas t o Chemical Processing Edited by Raymond P. Baddour and Roberl S. Timmins. The hl.1.T. P1.ess, Massachusetts Insiitule of Teahnology, Cambridge, 1967. svii 206 pp. Figs. aud tables. 1 X 23.3 rm. 312.1,0.

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High power eloctricnl discharges provide a convenient means of studying chemistry a t high temperatures. A typical plasma lorch employs a cantinuow stream of gaseous reactant, consumes several kilowatts of electricity, and produces temperatures ill the range of 2,000 to 20,000"K. Applications of these devices include the deposition of metallic films, production of crystals, and spheroidiaing of refractory compounds. Chemical engineers are cmrently iovestigntiug the eommercinl feasibility of employing high power plasmas t,o prodoce compounds such as nitric oxide, acetylene, eyanogen, and tetrafluoroethylene. This hook, a collection of nine papers, describes selected aspects of this research. Several papers, generally less than ten pages long, are brief reviem. Chapter 1 discusses t,he general physical characteristics of electrical discharges. Chapter 3 explores the application of high temperature discharges to chomical synthesis. Chapter 6 describes studies of microwave discharges and contains a three-page review of reactions in low pressure systems. The longer chapters a m reports of current research projects. These include: the arc fixation of nitrogen (Chapter 7); the conversion of graphite and hydrogen t o hydl.ocarbons a t high temperature (Chapter 8); and the preparation or flnarine componnds in plasma reactors (Chapter 9). The remaining pap el^ inehtde s. description of techniques used to mcmure the physical properties of thermal plasmas and a report of megawatt plasma generator design. Those who wish t o be inbroduced to this branch of chemical engineering will find this collection of papers to be quite useful. The text. is well writtell and well edited. Although n firm background in undergraduate physics and thermodynamics is a w m e d , the special lerminology of the subject. is carefully defined. Each chapter is self-eontaiued, and there is little dnplicatiml of material. Wheu applicable, caeh a i ~ t h o rrealistically appraises the associated economic and eugineeringproblems. The casual reador will probably find this book too weighty for browsing. On

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