8kb IRT CORP SAN DIEGO CALIF F/S 20/8 MOLECLJt.AR BEAM STUDIES OF LOW ENERGY REACTIONS. (U) OCT 78 B H NEYNABER, S V TANG

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1 r AD A059 8kb IRT CORP SAN DIEGO CALIF F/S 20/8 MOLECLJt.AR BEAM STUDIES OF LOW ENERGY REACTIONS. (U) OCT 78 B H NEYNABER, S V TANG N0001U 7k C OO11 UNCLASSIFIED IRT NL I END! 9845 I DAtt A1 onc Nj L.

2 IRT-81 3-øO8 j 00 1 OF 7 MOLECULAR BEAM STUDIES OF LOW ENERGY REACTIONS: /,. ) rf 1. >-/ DDC - r r Pnnfl Efl I 1UF T 13 E QNR CONTRACT No.LNAøø1 _?4_C : øø / II B PRINCIPAL INVESTIGATOR:,, R. H./NEYNABER /1 1 I RT Corporation -tti (/1 r OctØ F TfiThUTION STATEMZNf T1 Instrumentation 1 I IibthUeOD UuMmltSd Research Technology I c. - \ 7650 Convoy Court P.O Box ) San Diego. California 92138, C, Telex

3 p.... UNCLASSI FlED SECURI TY CLASSIFICA TION OF THIS PAGE (When Data Ent., d) E I IIAA E hjtatirtij OA READ INSTRUCTIONS tjm E i U BEFORE COMPLE TiNG FORM I REPORT NUMBER 2 GOVT ACCESSION NO. 3. RECIPIENTS CATALOG NUMBER 4 TITLE ( d SubIltS.) S. TYPE OF REPORT & PERIOD COVERED ANNUAL SUMMARY OF MOLECUL AR BEAM STUDIES OF Annual LOW ENERGY REACTIONS 6. PERFORMING ORG. REPORT NUMBER IRT_8lO3 OO S 7 AUT$OR(s B. CONTRACT OR GRANT NUMBER(.) R. H. Neynaber N C-OOlf S. Y. Tan g 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK AREA & WORK UNIT NUMBERS IRT Corporation P. 0. Box NR San Diego, CA II. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE ONR 2 October N. Quincy St. u. NUMBER OF PAGES Arlington, VA IA MONITORING AGENCY NAME 6 AOORESS(,1 d lk,.nt Icon. ContrOl Sing Office) IS. SECURITY CLASS. (of raped ) 16. DISTRIBUTION STATEMENT (of 1I,IO R apori) S C S Approved for public release; distribution unlimited. ISa. Unclassified OECLASS IFICATION DOWN GRAD ING SCHEDULE Ii. DISTRIBUTION STATEMENT (of the abstract ente,.d in Block 20, II difl.rant from R.port) 19 SUPPLEMENTARY NOTES A X EY WORDS (Continue on reverse a,de.1 necessar y and identif y by block nun.bec) Chemi-ionization Ion-molecule reactions Cro ss sec tions Molecular beams Reaction rates 20 ABSTRACT (Continue on r.v.ra. side if necess ary and identify by block n.omber) The annual summary of the resear ch performed under ONR Contract No. N C-0Oll is given. The report describes merg ing and crossed-beam studie of chemi-ionization and/or ion-molecule reactions. Included are investi- + * * * * * * + * gations of the Ne -He, He -He, He -0, Ne -Xe, He -Na, and He -Ne system. A description is also given of how this research helps resolve unknown aspec ts of the areas inves tigated. DD I EDITION OF I NOV SS IS OBSOLETE _ ,

4 SECURITY CLASSIFICATION OF THIS PAGE(Wh.n Data Ent.,.d) a.. c. SE CURITY CLAS SIrICAT ION F THIS PAGE Wh.n Data ne ed)

5 ACCE3SION for NTIS White Section V DOC Buff Section 0 UNANNOUNCED 0 JUSTIFICATION BY.. IJSTRIBUIION 1AVAIEABIUIY CODES Dist. AVAIL and/or SPECIAL Annual Summary of Molecular Bean Studies of Low Energy Reactions ONR Con tract No. N C-00ll 1. Contract Descrip tion Chemi-ionization and ion-molecule reactions involving metastable and ground-state atoms are studied by both cro ssed and merging beans at low relative energies (i.e., 0.01 to 10 or 20 ev). 2. Sc ientific Problem Some theories exist for chemi-ionization involving collisi6ns of metastable and ground-state rare gases. There is very l ittl e experimental data to test these theories over a range of relative kinetic energy from 0.01 to 10 or 20 ev. We will supp ly such data. Theoretical work for collis ions between two metastables is almost non-existent, and exper imental data is scant. We will supply experimental information such as absolute and relative cross sections and branching ratios for associative to Penning ionization. This information should establish pattern s to test those calculations that do exist and will stimulate further theory. Our chemi ionization data also will produce some information on unknown potentials * ** for the systems A B and C 0, where A, B, C, aid 0 are atoms and asterisks denote metastables. This information includes wel l depths and the dependence of the long range potential on internuclear separation. The composition of kev neutral rare gas beams formed by charge transfer of the rare gas paren t ion beam in alkali s i s unkn own. The beams consis t of rare gas metas tables (generally in two s tates) and ground-state atoms. The technique for generating such beams is common, and information on the compos ition is needed in analyzing data obtained through their use. We have developed a method for obtaining the fraction of ground-state atoms n such beans by s tudying appropriate ion-molecule reactions. We will apply this method to determine unknown compositions. 5_ 55

6 No experimental information exists on low-energy resonant or near-resonant charge-transfer reactions between rare gas ions and metastables. Our experiments will supply such information. The data can be used to see if existing theories for charge transfer between ions and ground-state atoms can be extended to this case. We also will investigate energy distributions of product ions from which information on the reaction kinetics can be obtained. 3. Scientific and Technical Approach Merging-beams techniques will be used for most of the studies. The two reactants of the process under investigation will be merged. Their velocities will be adjusted with respect to each other so that the desired relative energy in the center-of-mass system will be obtained. Product ions resulting from the reaction will be collected to give relative and absolute cross sections, and branching ratios will be obtained when appropriate. Some crossed-beams measurements will be made of the ion-molecule reactions at relative energies above 1 ev. Again product ions will be measured to obtain cross sections. 4.. rogress We have made the following progress during the past contract period. * * * * a) Chemi-ionization studies have been made for the Ne -He and He -He systems, and the results have been published. b) Chemi-ionization studies of the 11e D system hav e been repea ted. Th e new work covers a wider energy range and has produced more accurate results. Comparisons with current theory are made. c) We have determined that the fraction of ground-state atoms is 0.06 in composite helium beams generated by charge transfer of He in Na at ion energies of 1100 and 4000 ev. d) Experimental and theoretical cross sections were obtained for the charge- + * $ + * transfer reaction He (IS) + Ne - He + Ne where Ne in a composite of the 3 3 P and P0 states and EIe 2 represents a variety of excited states of He. 2

7 e) We have modified the detector magnet in our merging-beams apparatus in * order to study the chemi-ionizat i on of the Ne -Xe system. Previously the magnet could not he used to mass analyze ions as heavy as Xe + and NeXe at the desired energ ies. 5. Publications a) R. I-I. Neynaber and C. 0. Magnuson, Cheiai-ionization in Collisions of Metastable Argon with Sodium, J. Chem. Phys. 67, 430 (1977). b) R. H. N eynaber and S. Y. Tang, Chemi-ionization in Collision s of Metastable Uelium with Metastable Neon, J. Chem. Phys. 67, 5619 (1977). c) R. H. Neyn aber, C. D. Magnuson, and S.. Tang, Chemi-ionization in Collisions of Metastable Helium with Metastable helium, J. Chem. Phys. 68, 5112 (1978). 6. Extenuating Circumstances None Investi gators Dr. R Neynaber was the Principal Inves tigator during the past contract period. Dr. S. Y. Tang was also associated with the project.