New Products
Lock-in amplifiers will never be the same. Until now you've had to use a con ventional lock-in amplifier to dig out signals buried in noise. But con ventional lock-ins have problems. Like u n w a n t e d h a r m o n i c re sponses. Like phase instability with a tuned front end. Like overloading interference with a wide-band front end. Like grounding problems. Now there's a better tool available. Dynatrac. Using an entirely new approach to lock-ins—heterodyn ing—Dynatrac provides perform ance unmatched by conventional lock-ins at any price:
Reflection t u r b i d i m e t e r d e v e l o p e d at Oak Ridge uses t w o c o n c e n t r i c g r o u p s of fiber o p t i c s . One of t h e c h a n n e l s carries l i g h t t o t h e t u r b i d l i q u i d ; t h e second car ries t h e b a c k s c a t t e r e d l i g h t f r o m t h e l i q u i d t o a p h o t o c e l l where t h e a m o u n t of l i g h t is m e a s u r e d . T h e device can be u s e d wherever in situ m e a s u r e m e n t s of t u r b i d i t y are n e e d e d . Detailed drawings of t h e c i r c u i t and optical s y s t e m are avail able. Write t o Robert H. Lafferty, Jr., U n i o n C a r b i d e Corp., P.O. Box X, Oak Ridge, T e n n . 37830, or call 615-483-8611, ext. 3-1221 High-pressure injection valve for liquid c h r o m a t o g r a p h y , M o d e l HPSV-20, for use u p t o 3000 psi has an o f f - s t r e a m s a m p l e storage loop i n t o w h i c h t h e s a m p l e is loaded prior t o i n j e c t i o n . Detachable s a m p l e storage loops hold 20,100, ΟΓδΟΟμΙ. $295. C h r o m a t r o n i x , Inc. 415-841-7221
• Only Dynatrac's exclusive front end tracking filter eliminates extreme inter ference and harmonic responses, with out the instability problems associated with manual filters. • Only Dynatrac has an isolated front end that eliminates grounding problems. • Only Dynatrac has built-in RFI protec tion at all inputs and outputs. • Only Dynatrac operates to .1 Hz. • Only Dynatrac has full-scale sensitivity to 100 picovolts with optional remote preamp. • Only Dynatrac has all of the following: • Quadrature phase accuracy of .2 degrees. • Built-in variable frequency sine oscilla tor. • 12 db/octave output filter—essential in critical applications. • Full-scale sensitivity to 100 nanovolts without preamp. • Signal frequencies of .1 Hz to 200 KHz in optimized ranges—tracks external ref erence. • Noise mode for measuring narrow-band noise versus frequency. • Multi-turn vernier controls for phase, frequency and zero suppress. • Unsurpassed noise performance, over load capability, and output stability.
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Dynatrac's price? From under $1600. Lock-in amplifiers wil] never be the same. For com plete information or to arrange a demonstration, write to ITHACO. Inc., Box 818-5, Ithaca. New York 14850. Call 607-272-7640.
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Dynatrac. A new tool from ITHACO.
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Compact refrigerated bath/circulator c o n t a i n s V4-np c o m p r e s s o r a n d 8-liter reservoir. Clear work area is 8 3 / 4 X 4 a / 4 X 9-in. d e e p . T e m p e r a t u r e range is —30 t o +100°C. External circulation of bath f l u i d is p r o v i d e d . $695. Neslab I n s t r u m e n t s , Inc. 603-436-9444 418
c h a n g e s as s m a l l as 0.0002 OD u n i t s w i t h an o p t i c a l d e n s i t y of 2.0 OD units can be d e t e c t e d . $1985. S a n d a , Inc. 215-8498100 419
ANALYTICAL CHEMISTRY, VOL. 44,
For Multipoint
B.E.T. Surf ace Area d e t e r m i n a t i o n s , pore v o l u m e , pore size d i s t r i b u tions, adsorption and desorption i s o t h e r m s and t r u e powder d e n s i t y . Fast, accurate and d e p e n d a b l e . An all-metal c o n t i n u o u s Flow S y s t e m . Measures surface areas as low as 50 cm 2 (.005 m 2 )—with no upper limit. CIRCLE 165 ON READER SERVICE CARD
Monosorb Even if you never p e r f o r m e d a Surface Area de t e r m i n a t i o n , we guarantee the Monosorb will give you a correct answer in less t h a n 10 m i n u t e s on your first try. Direct reading one point B.E.T. Sur face Area Analyzer. Measures areas as low as 0.1 square m e t e r s CIRCLE 166 ON READER SERVICE CARD
Quantector A Three Station Outgassing System for simple a n d rapid s a m p l e p r e p a r a t i o n . A Built-in d e t e c t o r — m o n i t o r s t h e evolution of i m p u r i t i e s and i n f o r m s t h e user w h e n t h e s a m p l e is c l e a n . CIRCLE 167 ON READER SERVICE CARD
QUANTA CHROME CORPORATION 337 Glen Cove Road, Greenvale, N.Y. 11548 Phone: 516-671-0680 CIRCLE 167 ON READER SERVICE CARD
CIRCLE 111 ON READER SERVICE CARD ·
Quantasorb
Model C flow colorimeter is a s p l i t - b e a m , two-color d e t e c t i o n s y s t e m and uses p h o t o m u l t i p l i e r s for d e t e c t i n g m i n u t e absorbance changes. Absorption
Filamatic Model AB-P automatic pipet ting machine o f f e r s p u s h - b u t t o n selec t i o n of v o l u m e d i s p e n s e d . Seven inter c h a n g e a b l e syringes provide a range f r o m 0.025 cc t o 49.95 liters per fill cycle. V o l u m e can be a f u n c t i o n of t i m e , p H , refractive i n d e x , t u r b i d i t y , or a n y other variable. $867. National I n s t r u m e n t Co., Inc. 301-764-0900 420
80 A
Surface Measurement Instrumentation
NO. 14, DECEMBER
1972
