REPORT tive observation of low energy elec tron diffraction a n d photoelectric emission has been described {15). Another interesting a r r a n g e m e n t is a p u l s e d - b e a m system t h a t uses electrical detection, whereby t h e r e ciprocal lattice of the surface s t r u c t u r e is obtained as an oscilloscope display (16). T h i s brief resume of t h e instru m e n t a t i o n and applications of low energy electron diffraction has been prepared by the editors of ANALYTICAL
CHEMISTRY
for
Sephadex
Laboratory Columns A product of over six years' research know-how brings you these "exclusive" column features:
the
benefit of those a n a l y t i c a l chemists who have not y e t familiarized themselves with t h e fundamentals of t h e technique and who are u n aware of its capabilities and pos sibilities. References 2, 3, and 6 furnish descriptions cf t h e method t h a t are more replete with details, and t h e m a n y references therein, n o t a b l y to the p a p e r s of F a r n s worth, Germer, L a n d e r and M o r r i son, M a c R a c , and their coworkers, supply the needed information for details of experimental procedure. W i t h the a v a i l a b i l i t y of reliable commercial instrumentation al r e a d y a reality, it is expected t h a t the technique of low energy elec tron diffraction will continue to de velop as a n i m p o r t a n t a n a l y t i c a l method for the s t u d y of surface chemistry and r e l a t e d phenomena. Literature
Especially designed for Gel Filtration Chromatography Ion Exchange Chromatography
1 AQUEOUS AND ORGANIC SOLVENT SYS TEM COLUMNS—only columns specially de signed for use in these chromatographic systems 2 MIXING CHAMBER-of less than 1/10% of bed volume minimizes sample dilution to insure optimal zone sharpness for critical separations 3 INERT NYLON OR TEFLON NETTING-on the sample applicator, bottom endplece or flow adaptor eliminates adsorption of biologic material 4 DESCENDING TO RECYCLING OR UPWARD FLOW—easily converted by replacing both endpieces with new Sephadex Flow Adaptors
STANDARD SEPHADEX LABORATORY COLUMN FOR DESCENDING CHROMATOGRAPHY
Cited
(1) Willard F . Libby, Industrial Re search, 98, 77 (January 1967). (2) Lester H . Germer, Scientific Ameri can, 212, 32 (March 1965). (3) A. U. MacBae, Science, 139, 379 (February 1, 1963). (4) A. J. Pignoeco and G. E . Pellissier, J. Eleclrochem. Soc, 112, 1188 (1965). (5) R. L. Jacobson and G. K. Wehner, J. Appl. Phys., 36, 2674 (1965). (6) J. W. May, Ind. Eng. Chem., 57, 19 (July 1965). (7) G. W. Gobeli, J. J. Lander, and J. Morrison, J. Appl. Phys., 37, 203 (1966). (8) D . C. Johnson and A. U. MacRae, J. Appl. Phys., 37, 2298 (1966). (9) G. O. Krause, J. Appl. Phys., 37, 3691 (1966). (10) N . J. Tavlor, Surface Science, 4, 161 (1966). (11) R. E . Dicker, J. Sci. Instr., 42, 887 (1965). (12) J. C. Helmer, Am. J. Phys., 34, 222 (1966). (13) C. J. Todd, J. Sci. Instr., 42, 755 (1965). (14) C. W. Caldwell, Jr., Rev. Sci. Instr., 36, 1500 (1965). (15) G. Shinoda, S. Kato, S. Fujimoto, and H . Kobayashi, Rev. Sci. Instr., 37,533 (1966). (16) Robert L. Park and H. E . Farnsworth, Rev. Sci. Instr., 35, 1592 (1964).
RECYCLING UPWARD FLOW CHROMATOGRAPHY WITH NEW FLOW ADAPTORS
5 SAMPLE APPLICATOR-distributes the sam ple evenly over the bed surface to insure sharp zones for critical separations and protects as well as stabilizes the bed 6 SPECIAL DESIGN BED SUPPORT-ellmlnates troublesome sintered glass disc
AVAILABLE SEPHADEX COLUMNS AND ACCESSORIES SEPHADEX COLUMNS AQUEOUS SYSTEMS ACCESSORIES Type K. 15/30 Κ 15/90 Κ 25/45 Κ 25/45 "Jacketed" Κ 25/100 Κ 25/100 "Jaeketed" Κ 50/100 "Jacketed"
Cooling Jacket
Size cm 1.5x30 1.5x90 2.5x45 2.5x45 2.5x100 2.5x100 5.0x100
Sample Applicator
_ — _ s — S
-_ — S
_ — Ο
S S
Ο Ο
s
-
s
ο
SEPHADEX COLUMNS "SR" RESISTANT TO ORGANIC SOLVENTS SR25/45 SR25/100
2.5x45 2.5x100 S=Stanc ard Accessories
Flow Adaptors
— _ — — 0=Optional Accessories
S
S
ε
FLOW ADAPTORS' Flow Adaptors
To fit all K 25 Sephadex Lab. Columns
"Two Flow Adaptors should be used when conducting upward flow or recycling chromatography.
Information Service A comprehensive reference list, abstract cards, and other informa tion on Sephadex products are available. Direct Inquiries on your letterhead to the local Pharmacia representative or to:
P
h P H A R M A C I A FINE C H E M I C A L S I N C . 800 Centennial Avenue, Piscataway. N. J. 08854 Pharmacia (Canada) Ltd., 110 Place Crémazie, Suite 412, Montreal 11, P. Q.
(Inquiries outside U.S.A. end Canada should be directed to PHARMACIA FINE CHEMICALS, Uppsala, Sweden.) See us a t t h e F e d e r a t i o n M e e t i n g , B o o t h s 63, 64, 79-81. Circle No. 72 on Readers' Service Card
VOL. 39, NO. 4, APRIL 1907 ·
31 A
