Report for Analytical
an ion beam passes through a crys talline lattice, large attenuations in yield, such as those in Figures 7, 8, 10, may occur if the beam direction should inadvertently coincide with a crystal axis or plane. The result ing analytical error in extreme cases can be as large as a factor of 100 and (as we saw in Figure 10) it depends critically on where the foreign atoms are located within the lattice structure. Furthermore, it is not restricted to the elastic scattering process described here, but applies equally to all analytical methods requiring violent collisions William D. Mackin tosh, although born and raised in Canada, received hisB.Sc.attheUniversity of Glasgow, Scotland, in 1941. He spent the re mainder of the war years flying with the R.C.A.F. in the European Theatre of Operations. The five years following the war were spent in the rubber industry. He joined Atomic Energy of Canada in 1952. His work has been in the fields of isotope production, neutron activation analysis, and reactor chemistry. His pres ent interests are the exploitation of ac celerated particles and channeling for analytical purposes.
Literature
(1) S. Rubin, T . O. Passell, and L. E . Bailey, ANAL. C H E M . , 2 9 , 736 (1957).
(2) R . F . Sippel, Phys. Rev., 1 1 5 , 1441 (1959). (3) R. A. Semmler, J . F . Tribby, and J. E . Brugger, A.E.C; COO-712-89 (1964). (4) M. Peisach and D. O. Poole, ANAL. C H E M , 3 8 , 1345 (1966). (5) O. U. Anders, ANAL. C H E M . , 3 8 , 1442
(1966). (6) A. Turkevieh, K . Knolle, R. A. Emmert, W. A. Anderson, J . H . Patter son, and E . Franzgrote, Rev. Sci. Instrum., 37, 1681 (1966). (7) E. B0gh and E . Uggerh0j, Nucl. Instrum. Meth., 3 8 , 216 (1965). (8) J . A. Davies, J . Denhartog, and J . L. Whitton, Phys. Rev., 1 6 5 , 345 (1968). (9) J . H . Patterson, A. L. Turkevieh, and E. J . Franzgrote, J. Geophys. Res., 7 0 , 1311 (1965). (10) D. A. Thompson, H . D . Barber, and W. D . Mackintosh, Appl. Phys. Let ters,, in press. (11) D . Powers, W. K . Chu, and P . D . Bourland, Phys. Rev., 1 6 5 , 376 (1968).
Chemists
between the incident beam and the target atoms. Hence, analytical data obtained in a single crystal by charged-particle activation or by X-ray generation are also sus ceptible to serious error unless channeling is carefully avoided— a fact thrat has not yet been univer sally recognized by analysts. Even in polycrystalline material, similar (but smaller) errors can arise if the crystallites exhibit any significant degree of preferred orientation, as was clearly demonstrated by the range studies of McCargo et al. {20) in polycrystalline tungsten. John Davies was born in Prestalyn, North Wales, in 1927, but at the age of thirteen he emigrated to Can ada. He obtained his Ph.D. in phy sical chemistry at the University of Toronto in 1950, and since then has been working in the Research Chemistry branch at CRNL, investigating the pen etration of energetic atomic particles in matter. In 1963, he was one of the first experimentalists to observe the exist ence of "channeling." His subsequent research interests have centered around this channeling phenomenon and partic ularly on its application to other fields. The success of these researches led to the Noranda award from the Chemical Institute of Canada in 1965 and the T.D. Callinan award from the Electrochemical Society in 1968.
Cited
(12) J . Lindhard, Mat. Fys. Medd. Dansk. Vid Sekk, 3 4 (1965). (13) J . V . Andersen and E . Uggerh0j, Can. J. Phys., 4 6 , 517 (1968). (14) L. Eriksson, J . A. Davies, H . J . Denhartog, H . Matzke, and J . S. Whit ton, Can. Nucl. Technol., 5, 40 (1966). (15) J . A. Davies, J . Denhartog, L. Eriks son, and J . W. Mayer, Can. J. Phys., 45,4053 (1967). (16) E . B0gh, Proceedings of the Inter national Conference of Solid State Physics Research with Accelerators, BNL. 5O083 ( C - 5 2 ) , 76 (1967). (17) W. M . Gibson, F . W . Martin, R. Stensgaard, F . Palmgren Jensen, Ν . Τ . Meyer, G. Galster, A. Johansen, and I. Solsen, Can. J. Phys., 4 6 , 675 (1968). (18) L. Eriksson, J . A. Davies, N . G. E . Johansson, and J . W. Mayer, J. Appl. Phys., in press. (19) J . W. Mayer, J . A. Davies, and L. Eriksson, Appl. Phys. Letters, 1 1 , 365 (1967). (20) M . McCargo, J . A. Davis, and F . Brown, Can. J. Phys., 4 1 , 1231 (1963).
Doping G a s Mixtures. Arsine, Phosphine, Silane, Diborane in Ar gon, Helium, Hydrogen, Nitrogen. In various amounts and concen trations. For this year's catalog, write: Rare and Specialty Gases Dept., Airco Industrial G a s e s , ISO East 42nd Street, New York, N.Y. 10017.
AlRCO Industrial Gases
Circle No. 200 on Readers' Service Card
VOL. 4 1 , NO. 4 , APRIL 1 9 6 9 Φ 3 5 A
