SURFACE POLARITONS IN IRRADIATED α-QUARTZ

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SURFACE POLARITONS IN IRRADIATED α-QUARTZ

V. Umadevi, R. Kesavamoorthy, A. Sood, G. Venkataraman

To cite this version:

V. Umadevi, R. Kesavamoorthy, A. Sood, G. Venkataraman. SURFACE POLARITONS IN IRRADIATED α-QUARTZ. Journal de Physique Colloques, 1981, 42 (C6), pp.C6-81-C6-83.

�10.1051/jphyscol:1981625�. �jpa-00221337�

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JOURNAL DE PHYSIQUE

CoZloque C6, suppZ6ment au n O12, Tome 42, de'cembre 1981 page C6-81

SURFACE POLARITONS IN IRRADIATED a-QUARTZ

V. Umadevi, R. Kesavamoorthy, A.K. Sood and G. Venkataraman Reactor Research Centre, Kalpakkam 603 102, T a d 2 Nadu, India

P b s t r a c t . - S r f a c e p o l a r i t o n s ( S P ) i n c h a r g e d p a r t i c l e i r r a d i a t - e d d - q u a r t z a n d f u s e d q u a r t z h a v e b e e n s t u d i e d u s i n g t h e

a t t e n u a t e d t o t a l r e f l e c t i o n (ATR) method. It i s f o u n d t h a t o n i r r a d i a t i o n S P f r e q u e n c y d e c r e a s e s a n d l i n e w i d t h Y n c r e a s e s .

Some e v i d e n c e s p o i n t o u t t h a t o n i r r a d i a t i o n &-and f u s e d q u a r t z t e n d t o become d i s o r d e r e d i n a s i m i l a r way.

1. I n t r o d u c t i o n . - It i s b y now w e l l known t h a t a t a b o u n d a r y b e t w e e n two m e d i a w i t h d i e l e c t r i c c o n s t a n t s - E l >'t ) 0, s u r f a c e p o l a r i - t o n s ( S P ) p r o p a g a t e down t h e s u r f a c e . bk r e p o r t b e l o w o u r s t u d i e s o n t h e s u r f a c e p o l a r i t o n s i n - q u a r t z a n d f u s e d q u a r t z b y ATR t e c h n i q u e i n t h e s p e c t r a l o f 1400-180 C3n-l.

2. E x p e r i m e n t a l

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I r r a d i a t i o n s w e r e d o n e i n Sames & 1 5 , 1 5 0 k e V

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n e u t r o n g e n e r a t o r m o d i f i e d f o r c h a r g e d p a r t i c . i e - , r k . 100 k e V a r g o n , h e l i u m and d e u t e r i u m i o n s h a v e b e e n u s e d i n t h i s stud;b--a;-:ose

4 1017 i o n s / C h 2 , ATR s p e c t r a o f s i n g l e c r y s t a l s o f 4 -quartG.'=ut w i t h t h e o p t i c a x i s l y i n g i n t h e p l a n e o f t h e s a m p l e w e r e r e c o r d e d i n a B r k i n - E l m e r model 580 s p e c t r o p h o t o m e t e r b e f o r e and a f t e r i r r a d i a - t i o n . The ATR set u p u s e d i s a 25 r e f l e c t i o n s u n i t w i t h a KRS5 c r y s t a l . All t h e s p e c t r a r e p o r t e d h e r e a r e r e c o r d e d a t a f i x e d a n g l e

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o f i n c i d e n c e (30 1, c o r r e s p o n d i n g t o a f i x e d wave v e c t o r .

3. & s u l t s . - f i g u r e 1 shows t h e ATR s p e c t r a o f d - q u a r t z b e f o r e and a f t e r c h a r g e d p a r t i c l e i r r a d i a t i o n . The o r d i n a r y E t y p e SP a t 1 1 6 0 , 1145, 8 0 5 , 690, 485 a n d 400 Ch-I a r e s e e n c l e a r l y i n t h e u n i r r a d i a t e d s p e c t r u m . B u t e r i u m i o n s seem t o be more e f f e c t i v e t h a n a r g o n o r h e l i u m i o n s i n c a u s i n g damage. The g e n e r a l f e a t u r e o b s e r v e d o n irra- d i a t i o n i s t h a t t h e SP f r e q u e n c i e s s h i f t t o l o w e r v a l u e s and t h a t t h e l i n e s a r e b r o a d e n e d . It c a n a l s o be s e e n ( f i g u r e 2 ) t h a t t h e SP i n t h e s p e c t r a l r a n g e o f 1200-1000 ,&I-' c h a n g e s i g n i f i c a n t l y c o m p a r e d t o t h e modes i n t h e o t h e r r e g i o n s .

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1981625

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C6-82 JOURNAL DE PHYSIQUE

Fiq. 1 : A T R s p e c t r a o f u n i r r a d i a t e d a n d i r r a d i a t e d OC -

q u a r t z .

Shown i n f i g u r e 3 a r e t h e A T R s p e c t r a o f f u s e d q u a r t z r e c o r d e d s i m i -

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l a r l y . & h e a l s o t h e SP f r e q u e n c i e s d e c r e a s e a n d l i n e w i d t h s i n c r e a s e o n i r r a d i a t i o n c a n be s e e n d i s t i n c t l y . The asymmetry o n t h e h i g h e r f r e q u e n c y s i d e o f t h e SP a t

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¹¹⁴⁰ ^C~I" s u g g e s t s t h e p o s s i b l e p r e - s e n c e o f a n o t h e r mode s i m i l a r t o & - q u a r t z . I n d i c a t i o n s a r e t h a t b o t h d, - q u a r t z and f u s e d q u a r t z a t t a i n a common d i s o r d e r e d s t r u c t u r e o n i r r a d i a t i o n . b e c o u l d s p e c u l a t e t h a t t h i s i s a random s t r u c t u r e

F'iq. 2 : A T R s p e c t r a o f u n i r r a d i a t e d and i r r a d i a t e d @ - q u a r t z i n s p e c t r a l r a n e

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1300 - ¹⁰⁵⁰ On-

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Fiq. 3 : ATR s p e c t r a o f u n i r r a d i a t e d f u s e d q u a r t z .

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w i t h d a n g l i n g bonds.

4. D i s c u s s i o n . - I r r a d i a t i o n c h a n g e s t h e s p e c u l a r r e f l e c t i v i t y s p e c t r a a l s o 1

.

D i e l e c t r i c c o n s t a n t ( < I c a l c u l a t e d f r o m t h e b u l k r e f l e c t i v i t y d a t a u s i n g Kramers- Kronig a n a l y s i s d o e s n o t a c c o u n t f o r t h e o b s e r v e d c h a n g e s i n t h e ATR s p e c t r a . ?he same c o n c l u s i o n was a r r i v e d a t b y

Z h i z h i n e t a 1 2 i n n i t r o g e n i r r a d i a t e d & - q u a r t z . As t h e p r o j e c t e d r a n g e o f t h e p a r t i c l e s u s e d f o r i r r a d i a t i o n i s s m a l l e r t h a n t h e s k i n d e p t h o f i n f r a r e d r a d i a t i o n a t t h e s e f r e q u e n c i e s , i t i s p r o p o s e d t o a n a l y z e t h e b u l k r e f l e c t i v i t y d a t a i t s e l f o n t h e b a s i s o f a two l a y e r model. The o b t a i n e d t h u s s h o u l d b e u s e d t o g e n e r a t e ATR s p e c t r a c a l c u l a t e d f o r a t h r e e i n t e r f a c e c a s e . M t e r g e n e r a t i n g c o m p l e t e d i s p e r s i o n c u r v e d a t a , e f f o r t s w i l l b e made t o a n a l y z e o u r d a t a o n t h e s e l i n e s .

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REFERENCES

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1. linadevi, U., Sahu, H K., S o d , R K. a n d Venkatararnan, G , R o c . NIC. h y s . a n d S l i d S t a t e Fhys. a m p . %2 S o l i d % a t e b y - s i c s , p. 755 (1979 ).

2. Z h i z h i n , G.N., Yakolev, V.A. a n d S h i r m e r , G , JETP Lett. 29, 315 (1979 I.

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