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Electron microscopic replica studies of porosity in fused iron catalysts
VACUUM Classified Abstracts
II - -
Vacuum
Apparatus
and Auxiliaries
~
II
Abstract No. and References
Contd.
On the Application of a Philips Ionisation Gauge Type of Ion Source in a Mass Spectrometer Leak Detector
21/I1
See A b s t r a c t No. : 4 1 / I I
Leak Detection with a Mass Spectrometer Using Hydrogen Gas
72/Ii
See A b s t r a c t No. : 4 2 / I I
23/11
Process Control by Mass Spectrometer See A b s t r a c t No. : 4 6 / I
The Electron Microscope and Its Industrial Application United Kingdom. T h e u n a i d e d eye c a n n o t s e p a r a t e l y distinguistl two p o i n t s l y i n g less t h a n 0.1 r a m . a p a r t .
O
T h e l i g h t microscope h a s a resolution l i m i t of a p p r o x i m a t e l y 0.5 A . . T h e t h e o r e t i c a l resolution limit of t h e electron microscope is 0.03A, t h e practical l i m i t is a p p r o x i m a t e l y 40A. T h e o p e r a t i o n of a n electron microscope is b a s e d o n t h e fact t h a t electrons c a n be 'deflected b y either electrical or m a g n e t i c fields, b o t h principles b e i n g u s e d in t h e f o r m of electron lenses. A n electron microscope e s s e n t i a l l y consists of a n electron g u n p r o d u c i n g e l e c t r o n s w h i c h are artificially accelerated to t h e required e n e r g y a n d t r a v e l t h r o u g h t h e c h a m b e r in a d i v e r g i n g b e a m . B y m e a n s of a n electron c o n d e n s e r lens t h i s diverging b e a m is c o n v e r t e d into a parallel b e a m directing t h e electrons to t h e specimen. Below t h e s p e c i m e n is a n objective lens m a g n i f y i n g t h e i m a g e f r o m 30x to 100x. Finally, a p r o j e c t o r lens is provided, giving a n a d d i t i o n a l m a g n i f i c a t i o n of 175x. T h u s t h e total m a g n i f i c a t i o n p r o d u c e d b y t h e i n s t r u m e n t is 17,500x. T h e p r o v i s i o n of a second p r o j e c t o r lens m a y increase t h i s figure to 100,000x. T h e t u b e is e v a c u a t e d to 10-~mm. H g d u r i n g operation. To allow for t h e m a n i p u l a t i o n of t h e p h o t o g r a p h i c plate a n d t h e s p e c i m e n w i t h o u t b r e a k i n g t h e v a c u u m in t h e t u b e air locks are fitted to t h e i n s t r u m e n t in a suitable position. Special t e c h n i q u e s h a v e b e e n developed for t h e p r e p a r a t i o n of s p e c i m e n s to be u s e d in t h e electron microscope. T h e s p e c i m e n m u s t be m o u n t e d on a sup.port w h i c h does n o t stop t h e t r a n s m i s s i o n of electrons, i.e., t h e m o u n t i n g films s h o u l d n o t be t h i c k e r t h a n 200 ~ . T h e s p e c i m e n itself h a s to w i t h s t a n d h i g h v a c u u m c o n d i t i o n s a n d m u s t be dry. Various s p e c i m e n p r e p a r a t i o n t e c h n i q u e s are discussed, i n c l u d i n g s h a d o w - c a s t i n g . Finally, replica t e c h n i q u e s are m e n t i o n e d . I n conclusion t h e a u t h o r calls for t h e d e v e l o p m e n t of n e w s p e c i m e n p r e p a r a t i o n t e c h n i q u e s w h i c h facilitate effective e x a m i n a t i o n of living o r g a n i s m s in t h e electron microscope. Sommaire : Discussion de la thdorie, de la c o n s t r u c t i o n et des a p p l i c a t i o n s du microscope dlectronique.
24/II
Article by J. W. Sharpe Chem. & Industr. 17.11.51. 976-981 25/1I
Carbon Gel as Revealed by the Electron Microscope See A b s t r a c t No. : 3 0 / I I
Electron Microscopic Replica Studies of Porosity in Fused Iron Catalysts United States. A t y p i c a l fused iron (FesO4-MgO-K30) s y n t h e t i c a m m o n i a c a t a l y s t was to be e x a m i n e d u n d e r
O
t h e electron microscope after r e d u c t i o n in h y d r o g e n . T h e r a w c a t a l y s t consisted of a solid solution of m a g n e t i t e a n d t h e s t r u c t u r a l p r o m o t e r s . Prior to t h e r e d u c t i o n t h e r e w a s v i r t u a l l y no p o r o s i t y or i n t e r n a l s u r f a c e area. .ks a result of t h e v o l u m e c h a n g e ill t h e t r a n s f o r m a t i o n f r o m m a g n e t i t e to a l p h a - i r o n d u r i n g t h e r e d u c t i o n in h y d r o g e n , a fine p o r o u s s t r u c t u r e w i t h a h i g h surface a r e a w a s formed. T h e a v e r a g e d i m e n s i o n s of t h e s e pores were e s t i m a t e d a t 370 a n d 800 ~ for r e d u c t i o n t e m p e r a t u r e s o f 450°C a n d 550°C respectively. T h e e x a m i n a tion of replicas t a k e n f r o m t h e surface of t h e r e d u c e d c a t a l y s t in t h e electron microscope r o u g h l y c o n f i r m e d t h e s e e s t i m a t e d pore sizes. D e t a i l s are g i v e n of t w o m e t h o d s e m p l o y e d for t h e p r o d u c t i o n of t h e replicas, n e g a t i v e f o r m v a r a n d positive silica replicas. Pieces of t h e c a t a l y s t were polished on one surface prior to r e d u c t i o n a n d a f t e r r e d u c t i o n d i p p e d in a 0.5% solution of f o r m v a r in e t h y l e n e dichloride. S u b s e q u e n t l y , a 10~o solution of nitro-cellulose in b u t y l a c e t a t e was s p r e a d over t h e surface, dried a n d t h e double film peeled off. T h e replica w a s s h a d o w e d w i t h c h r o m i u m e v a p o r a t e d a t a n angle of 10 ° w i t h t h e film surface. Finally, t h e s p e c i m e n screen w a s f a s t e n e d to t h e f o r m v a r side of t h e film a n d t h e a s s e m b l y dipped in a m y l acetate, in order to dissolve t h e nitro-cellulose. A f t e r d r y i n g t h e s p e c i m e n w a s r e a d y for use. I n t h e case of t h e silica replica, a 10% solution of nitro-cellulose w a s s p r e a d o n t h e m e t a l surface, dried a n d t h e film peeled off. S u b s e q u e n t l y silica w a s e v a p o r a t e d on to t h e replica a n d in s o m e i n s t a n c e s t h e replica was s h a d o w e d in a d d i t i o n w i t h c h r o m i u m . T h e nitro-cellulose was dissolved in t h e m a n l i e r described before. Sommaire : O n d o n n e des d6tails s u r les r e p r o d u c t i o n s de t e c h n i q u e s p o u r l'dtude de la porosit6 darss des c a t a l y s e u r s en fer f o n d u sous le microscope 61ectronique.
Production of Small Apertures by Evaporation Techniques
26/II
Article by L. T. McCartney & R. B. Anderson J. AppL Phys. 22, Dec. 1951 1441-1443 27/1I
See A b s t r a c t No. : 6 4 / I I I
January, 1952
Vacuum VoL I I No. I
80
II - -
Vacuum
Apparatus
and Auxiliaries
~
II
Abstract No. and References
Contd.
On the Application of a Philips Ionisation Gauge Type of Ion Source in a Mass Spectrometer Leak Detector
21/I1
See A b s t r a c t No. : 4 1 / I I
Leak Detection with a Mass Spectrometer Using Hydrogen Gas
72/Ii
See A b s t r a c t No. : 4 2 / I I
23/11
Process Control by Mass Spectrometer See A b s t r a c t No. : 4 6 / I
The Electron Microscope and Its Industrial Application United Kingdom. T h e u n a i d e d eye c a n n o t s e p a r a t e l y distinguistl two p o i n t s l y i n g less t h a n 0.1 r a m . a p a r t .
O
T h e l i g h t microscope h a s a resolution l i m i t of a p p r o x i m a t e l y 0.5 A . . T h e t h e o r e t i c a l resolution limit of t h e electron microscope is 0.03A, t h e practical l i m i t is a p p r o x i m a t e l y 40A. T h e o p e r a t i o n of a n electron microscope is b a s e d o n t h e fact t h a t electrons c a n be 'deflected b y either electrical or m a g n e t i c fields, b o t h principles b e i n g u s e d in t h e f o r m of electron lenses. A n electron microscope e s s e n t i a l l y consists of a n electron g u n p r o d u c i n g e l e c t r o n s w h i c h are artificially accelerated to t h e required e n e r g y a n d t r a v e l t h r o u g h t h e c h a m b e r in a d i v e r g i n g b e a m . B y m e a n s of a n electron c o n d e n s e r lens t h i s diverging b e a m is c o n v e r t e d into a parallel b e a m directing t h e electrons to t h e specimen. Below t h e s p e c i m e n is a n objective lens m a g n i f y i n g t h e i m a g e f r o m 30x to 100x. Finally, a p r o j e c t o r lens is provided, giving a n a d d i t i o n a l m a g n i f i c a t i o n of 175x. T h u s t h e total m a g n i f i c a t i o n p r o d u c e d b y t h e i n s t r u m e n t is 17,500x. T h e p r o v i s i o n of a second p r o j e c t o r lens m a y increase t h i s figure to 100,000x. T h e t u b e is e v a c u a t e d to 10-~mm. H g d u r i n g operation. To allow for t h e m a n i p u l a t i o n of t h e p h o t o g r a p h i c plate a n d t h e s p e c i m e n w i t h o u t b r e a k i n g t h e v a c u u m in t h e t u b e air locks are fitted to t h e i n s t r u m e n t in a suitable position. Special t e c h n i q u e s h a v e b e e n developed for t h e p r e p a r a t i o n of s p e c i m e n s to be u s e d in t h e electron microscope. T h e s p e c i m e n m u s t be m o u n t e d on a sup.port w h i c h does n o t stop t h e t r a n s m i s s i o n of electrons, i.e., t h e m o u n t i n g films s h o u l d n o t be t h i c k e r t h a n 200 ~ . T h e s p e c i m e n itself h a s to w i t h s t a n d h i g h v a c u u m c o n d i t i o n s a n d m u s t be dry. Various s p e c i m e n p r e p a r a t i o n t e c h n i q u e s are discussed, i n c l u d i n g s h a d o w - c a s t i n g . Finally, replica t e c h n i q u e s are m e n t i o n e d . I n conclusion t h e a u t h o r calls for t h e d e v e l o p m e n t of n e w s p e c i m e n p r e p a r a t i o n t e c h n i q u e s w h i c h facilitate effective e x a m i n a t i o n of living o r g a n i s m s in t h e electron microscope. Sommaire : Discussion de la thdorie, de la c o n s t r u c t i o n et des a p p l i c a t i o n s du microscope dlectronique.
24/II
Article by J. W. Sharpe Chem. & Industr. 17.11.51. 976-981 25/1I
Carbon Gel as Revealed by the Electron Microscope See A b s t r a c t No. : 3 0 / I I
Electron Microscopic Replica Studies of Porosity in Fused Iron Catalysts United States. A t y p i c a l fused iron (FesO4-MgO-K30) s y n t h e t i c a m m o n i a c a t a l y s t was to be e x a m i n e d u n d e r
O
t h e electron microscope after r e d u c t i o n in h y d r o g e n . T h e r a w c a t a l y s t consisted of a solid solution of m a g n e t i t e a n d t h e s t r u c t u r a l p r o m o t e r s . Prior to t h e r e d u c t i o n t h e r e w a s v i r t u a l l y no p o r o s i t y or i n t e r n a l s u r f a c e area. .ks a result of t h e v o l u m e c h a n g e ill t h e t r a n s f o r m a t i o n f r o m m a g n e t i t e to a l p h a - i r o n d u r i n g t h e r e d u c t i o n in h y d r o g e n , a fine p o r o u s s t r u c t u r e w i t h a h i g h surface a r e a w a s formed. T h e a v e r a g e d i m e n s i o n s of t h e s e pores were e s t i m a t e d a t 370 a n d 800 ~ for r e d u c t i o n t e m p e r a t u r e s o f 450°C a n d 550°C respectively. T h e e x a m i n a tion of replicas t a k e n f r o m t h e surface of t h e r e d u c e d c a t a l y s t in t h e electron microscope r o u g h l y c o n f i r m e d t h e s e e s t i m a t e d pore sizes. D e t a i l s are g i v e n of t w o m e t h o d s e m p l o y e d for t h e p r o d u c t i o n of t h e replicas, n e g a t i v e f o r m v a r a n d positive silica replicas. Pieces of t h e c a t a l y s t were polished on one surface prior to r e d u c t i o n a n d a f t e r r e d u c t i o n d i p p e d in a 0.5% solution of f o r m v a r in e t h y l e n e dichloride. S u b s e q u e n t l y , a 10~o solution of nitro-cellulose in b u t y l a c e t a t e was s p r e a d over t h e surface, dried a n d t h e double film peeled off. T h e replica w a s s h a d o w e d w i t h c h r o m i u m e v a p o r a t e d a t a n angle of 10 ° w i t h t h e film surface. Finally, t h e s p e c i m e n screen w a s f a s t e n e d to t h e f o r m v a r side of t h e film a n d t h e a s s e m b l y dipped in a m y l acetate, in order to dissolve t h e nitro-cellulose. A f t e r d r y i n g t h e s p e c i m e n w a s r e a d y for use. I n t h e case of t h e silica replica, a 10% solution of nitro-cellulose w a s s p r e a d o n t h e m e t a l surface, dried a n d t h e film peeled off. S u b s e q u e n t l y silica w a s e v a p o r a t e d on to t h e replica a n d in s o m e i n s t a n c e s t h e replica was s h a d o w e d in a d d i t i o n w i t h c h r o m i u m . T h e nitro-cellulose was dissolved in t h e m a n l i e r described before. Sommaire : O n d o n n e des d6tails s u r les r e p r o d u c t i o n s de t e c h n i q u e s p o u r l'dtude de la porosit6 darss des c a t a l y s e u r s en fer f o n d u sous le microscope 61ectronique.
Production of Small Apertures by Evaporation Techniques
26/II
Article by L. T. McCartney & R. B. Anderson J. AppL Phys. 22, Dec. 1951 1441-1443 27/1I
See A b s t r a c t No. : 6 4 / I I I
January, 1952
Vacuum VoL I I No. I
80