MÖSSBAUER AND ELECTRON SPIN RESONANCE STUDY OF ELECTRON IRRADIATED FERROCYANIDE IONS IN KCl LATTICE

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MÖSSBAUER AND ELECTRON SPIN RESONANCE STUDY OF ELECTRON IRRADIATED

FERROCYANIDE IONS IN KCl LATTICE

R. Scorzelli, J. Danon, N. Vugman

To cite this version:

R. Scorzelli, J. Danon, N. Vugman. MÖSSBAUER AND ELECTRON SPIN RESONANCE STUDY

OF ELECTRON IRRADIATED FERROCYANIDE IONS IN KCl LATTICE. Journal de Physique

Colloques, 1979, 40 (C2), pp.C2-568-C2-570. �10.1051/jphyscol:19792198�. �jpa-00218576�

JOURNAL DE PHYSIQUE

Colloque C2, supplkment au n o 3, Tome

40,

mars

1979,

page C2-568

MOSSBAUER AND ELECTRON SPIN RESONANCE STUDY OF ELECTRON IRRADIATED FERROCYAN I DE IONS IN KC1 L A T T I C E

R. S c o r z e l l i , J. Danon and N . V . vugmanX

Centro B r a s i l e i r o de Pesquisas F i s i c a s , Av. Wenceslau Braz, n o 71, 20 000 Rio de Janeiro, R.J., B r a s i l .

? n s t i t u t o de Fisica, Universidade Federal do Rio de J m e i r o , Bloco A, Cidade U n i v e r s i t a r i a , 20 000 Rio de Janeiro, R. J., B r a s i l .

REsum6.- Les i o n s F e l I ( c N ) ~ - d i l u e s d a n s un r 6 s e a u de KC1 o n t d t d i r r a d i g s

B

b a s s e t e m p e r a t u r e a v e c d e s e l e c t r o n s de 2 MeV. Les cyano-complexes d e F e I formes p a r l ' i r r a d i a t i o n , o n t 6 t d e t u d i e s 1 l ' a i - d e de l a s p e c t r o s c o p i e M6ssbauer e t RPE.

A b s t r a c t . - F e l l ( ~ N ) ; - i o n s d i l u t e d i n KC1 l a t t i c e were i r r a d i a t e d a t low t e m p e r a t u r e s w i t h 2 MeV e l e c t r o n s . The F ~ I cyanocomplexes formed by r a d i a t i o n h a s b e e n s t u d i e d by M.S. and ESR measurements.

A l k a l i - m e t a l h a l i d e s have been u s e d a s m a t r i c e s i n v a r i o u s t y p e s o f s p e c t r o s c o p i c s t u d i e s w i t h t r a n s i -

t i o n m e t a l complexes. T h i s h a s b e e n p a r t i c u l a r l y u s e f u l 1 i n t h e ESR / I - 4 / , o p t i c a l and i n f r a r e d s t u - d i e s / 5 , 6 / of n o v e l s p e c i e s formed by e l e c t r o n and X-ray i r r a d i a t i o n e f f e c t s i n t h e complex i o n s . I n t h e p r e s e n t work we i n v e s t i g a t e d t h e a p p l i c a b i - l i t y o f t h e Mzssbauer s p e c t r o s c o p y (M.S.) f o r t h e s e k i n d of s t u d i e s by comparing t h e r e s u l t s from ESR w i t h t h o s e o b t a i n e d from M.S. i n i r r a d i a t e d KuFe

(CN), i n KC1.

E x p e r i m e n t a l . - Doped samples were o b t a i n e d by c r y s - t a l l i z a t i o n of K C 1 from aqueous s o l u t i o n c o n t a i n i n g K,FeII(CN),.3H20 i n 0 . 2 5 % M p r o p o r t i o n . P o l y c r y s - t a l l i n e s a m p l e s w i t h i s o t o p i c a l l y h i g h l y e n r i c h e d complex ( 9 0 . 6 2 " ~ e ) was used i n M.S. work. F o r t h e ESR work s i n g l e c r y s t a l s were grown from a n e q u i v a - l e n t s o l u t i o n w i t h t h e non e n r i c h e d complex.

A l l samples were i r r a d i a t e d a t l i q u i d n i t r o g e n tem- p e r a t u r e w i t h a 2 MeV e l e c t r o n beam of a n e l e c t r o n l i n e a r a c c e l e r a t o r d u r i n g 15 m i n u t e s and a c u r r e n t o f 20 PA.

M.S. were r e c o r d e d w i t h a s i n u s o i d a l d r i v e coupled t o a H e w l e t t - P a c k a r d m u l t i c h a n n e l a n a l y s e r o f 1024 c h a n n e l s . A 20 ~ C ~ ~i n Rh h a s b e e n u s e d a s s o u r c e C O and t h e isomer s h i f t ( I . S . ) d a t a a r e r e p o r t e d w i t h r e s p e c t t o m e t a l l i c i r o n . Low t e m p e r a t u r e measure- ments were performed i n h e l i u m c r y o s t a t . A 370/145 IBM computer was u s e d f o r f o l d i n g and a n a l y s i n g t h e d a t a , w i t h a l o r e n t z i a n l e a s t s q u a r e f i t t i n g . The X-band ( 9 . 5 GHz) ESR s p e c t r a were o b t a i n e d w i t h a V a r i a n E-12 s p e c t r o m e t e r e q u i p e d w i t h a H e w l e t t - P a c k a r d 53406 f r e q u e n c y c o u n t e r and a D i g i t a l NMR

3193 g a u s s m e t e r . Q-band measurements (35 GHz) were p e r f o r m e d i n a V a r i a n 4500 s p e c t r o m e t e r i n o r d e r t o o b t a i n a n g u l a r v a r i a t i o n and t o check on t h e cohe- r e n c e of t h e s p e c i e s a s s i g n e m e n t s .

A l l ESR s p e c t r a have been t a k e n a t l i q u i d n i t r o g e n t e m p e r a t u r e . The c r y s t a l s were mounted i n a c o l d f i n g e r c r y o s t a t i n s u c h a way t h a t t h e y c o u l d be r o t a t e d around one o f t h e p r i n c i p a l a x e s . When any of t h e o t h e r two a x e s o f t h e c r y s t a l i s p a r a l l e l t o t h e a p p l i e d m a g n e t i c f i e l d one o b t a i n s , i n one s c a n n i n g , b o t h t h e p a r a l l e l and t h e p e r p e n d i c u l a r f e a t u r e s o f t h e s p e c t r u m . T h i s g i v e s a n immediate check on t h e a x i a l symmetry of t h e p a r a m a g n e t i c s p e c i e s under s t u d y .

R e s u l t s . - F i g u r e 1 r e p r o d u c e s t h e M.S. o b t a i n e d a t 4.2K of t h e i r r a d i a t e d samples. The s p e c t r u m i s de- composed i n t o a c e n t r a l s i n g l e t and two d o u b l e t s and from t h e computer f i t t i n g one o b t a i n s t h e c o r - r e s p o n d i n g MEssbauer p a r a m e t e r s which a r e l i s t e d i n t a b l e I.

T a b l e I

I.S. AE I-

( m / s ) (mm/s) ( m / s )

S ~ n g l c t -0.106 .38

Inner doublet +0.054 0.77 .37

Outer doublet t0.069 1.59 .37

The c e n t r a l l i n e c o r r e s p o n d s t o t h e u n i r r a d i a t e d complex and t h e two d o u b l e t s a r e formed by t h e i r r a d i a t i o n .

These d o u b l e t s p r e s e n t t h e same I . S . v a l u e , which i s s h i f t e d o f +0.15 mm/s a s compared t o t h a t of t h e F ~ ~ ~ ( c N ) : - s p e c i e s . The v a l u e s of t h e quadru-

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792198

p o l e s p l i t t i n g s (Q.S.) o f t h e i n n e r and t h e o u t e r d o u b l e t s a r e i n t h e r a t i o 1:2.

VELOCITY ( m / s I COUNTINO RATE *lo3

F i g . l : MEssbauer s p e c t r a o f e l e c t r o n i r r a d i a t e d F ~ ( c N ) ~ - i o n s i n KC1 a t 4.2K.

3 200

3000

I 2 800

The ESR s p e c t r a o b s e r v e d i n t h e i r r a d i a t e d s a m p l e s r e v e a l t h e p r e s e n c e o f t h r e e a x i a l l y s y m m e t r i c p a r a - m a g n e t i c s p e c i e s , w h i c h we l a b e l A , B and C. T h e s e

s p e c i e s h a v e a p p r o x i m a t e l y t h e same

g l 1

v a l u e w h i c h i s c l o s e t o t h e f r e e e l c t r o n v a l u e . T h i s l e a d s t o t h e s u p e r i m p o s i t i o n o f t h e i r p a r a l l e l s p e c t r a . The p e r p e n d i c u l a r s p e c t r a o f t h e s e s p e c i e s a r e v e r y w e l l r e s o l v e d and a r e r e p r o d u c e d i n f i g u r e 2 .

The p e r p e n d i c u l a r s p e c t r u m o f s p e c i e s A c o n s i s t s o f s e v e n e q u i d i s t a n t l i n e s o f r e l a t i v e i n t e n s i t i e s

1:2:3:4:3:2: 1. T h i s s p e c t r u m c a n be a t t r i b u t e d t o t h e i n t e r a c t i o n o f a n u n p a i r e d e l e c t r o n w i t h two e q u i v a l e n t c h l o r i n e n u c l e i 1 2 1 .

The p e r p e n d i c u l a r s p e c t r u m o f s p e c i e s B c o n s i s t s o f n i n e l i n e s o f r e l a t i v e i n t e n s i t i e s 1 : 1 : 2 : 1 : 2 : 1 : 2 : 1 : 1 w h i c h c a n b e i n t e r p r e t e d a s a r i s i n g f r o m t h e i n t e - r a c t i o n o f one u n p a i r e d e l e c t r o n w i t h one c h l o r i n e and o n e n i t r o g e n n u c l e u s . The s p e c t r u m c a n b e f i t t e d by a s s u m i n g t h e c h l o r i n e s u p e r h y p e r f i n e i n t e r a c t i o n t o b e t w i c e a s l a r g e a s t h a t c o r r e s p o n d i n g t o t h e n i t r o g e n i n t e r a c t i o n .

The p e r p e n d i c u l a r s p e c t r u m o f s p e c i e s C c o n s i s t s o f a d o u b l e t o f p o o r l y r e s o l v e d t r i p l e t s w h i c h c a n b e a t t r i b u t e d t o t h e i n t e r a c t i o n o f a n u n p a i r e d e l e c - t r o n w i t h one n i t r o g e n and a p r o t o n .

1

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-1 4 6 -073 0 -073 *L46

F i g . 2 : X-band (v = 9352.21 MHz) s p e c t r a

l e f t : f i r s t d e r i v a t i v e p e r p e n d i c u l a r s p e c t r u m of s p e c i e s A.

r i g h t : s e c o n d d e r i v a t i v e p e r p e n d i c u l a r s p e c t r a o f s p e c i e s B and C.

The r e l a t i v e i n t e g r a t e d i n t e n s i t i e s o f t h e s p e c i e s A and B s p e c t r a i s a p p r o x i m a t e l y I : ] .

C2-570

JOURNAL DE PHYSIQUE

S i m i l a r ESR s p e c t r a have been o b s e r v e d / 3 / a f t e r s e v e r a l h o u r s room t e m p e r a t u r e g a m m a - i r r a d i a t i o n f o l l o w e d by h e a t i n g a t 400K of p o l y c r y s t a l l i n e sam- p l e s o f K F ~ " ( c N ) .3H 0 doped i n K C 1 . S p e c i e s A

6 2

and B have been o b s e r v e d p r e v i o u s l y a f t e r t h r e e h o u r s X-ray i r r a d i a t i o n a t 77K f o l l o w e d by an annea- l i n g a t 618K of t h e same complex i n an NaCl s i n g l e c r y s t a l

/ & I .

The g l v a l u e of s p e c i e s A measured i n t h e p r e s e n t work was found t o be s i g n i f i c a n t l y l a r g e r t h a n t h a t r e p o r t e d i n / 3 / .

The s p i n - h a m i l t o n i a n p a r a m e t e r s of t h e o b s e r v e d spe- c i e s a r e l i s t e d i n t a b l e 11.

T a b l e I1

Species 81 g l l ,cl I a ,CI

, ,

^a

^4.

^{('I A!'}

⁴¹

A 2.219 1.995 4.5 8.3 - -

- -

B 2.093 2.000 4.4 b 2.0 b - -

C 2.107 ~2.00

-

^1.8 b 5.8 b

a - average values for 3 5 ~ 1 and 3 7 ~ 1 isotopes.

b

-

unresolved.

D i s c u s s i o n . - The g v a l u e s o f t h e p a r a m a g n e t i c spe- c i e s ( T a b l e 11) i n d i c a t e t h a t t h e u n p a i r e d e l e c t r o n i s l o c a t e d i n a d Z 2 o r b i t a l /1,2/'. The e l e c t r o n con- f i g u r a t i o n o f a l l t h r e e A , B and C s p e c i e s i s t h u s ( t , g ) 6 ( e g ) 1 , which c o r r e s p o n d s t o a 3 d 7 low-spin s t a t e of F e ( 1 ) . The main e f f e c t of t h e i r r a d i a t i o n i s t h e r e d u c t i o n o f F e ( I 1 ) i n t h e d i a m a g n e t i c (S=O) low-spin c o n f i g u r a t i o n 3d6 t o t h e p a r a m a g n e t i c (S= 112) low-spin c o n f i g u r a t i o n 3d7. T h i s i n c r e a s e of d - e l e c t r o n d e n s i t y i s c o m p a t i b l e t o t h e d e c r e a s e i n s - e l e c t r o n d e n s i t y i n d i c a t e d by t h e o b s e r v e d v a r i a t i o n AIS = +0.15 mm/s/7/.

The p r e s e n c e of q u a d r u p o l e h y p e r f i n e i n t e r a c t i o n i n d i c a t e s t h a t i n t h e s e new low-spin F e ( I ) cyano- complexes t h e c u b i c symmetry o f t h e F ~ I I ( c N )

z-

^{i s}

n o t p r e s e r v e d . T h i s i s i n a g r e e m e n t w i t h t h e ESR a s s i g n e m e n t s d e r i v e d from t h e l i n e i n t e n s i t i e s which i n d i c a t e s t h a t s p e c i e s A i s w e l l d e s c r i b e d by

t h e

1

F ~ I ( C N ) ~ C ~ ~

1 '-

complex w h e r e a s s p e c i e s B a s

I

F ~ ' ( c N ) ,C P ~

-

^complex.

Fkom symmetry a r g u m e n t s one e x p e c t s t o o b s e r v e a r a t i o 1:2 o f Q.S. o f a n MX,Y and a MX4Y2 c o n f i g u r a - t i o n , when M i s a low-spin d i a m a g n e t i c i o n / 7 / . T h i s h a s b e e n o b s e r v e d wich c i s and t r a n s i s o m e r s of F e ( I 1 ) and I r ( I I 1 ) complexes / 8 / . The same argu- ments a p p e a r s t o h o l d w i t h t h e p a r a m a g n e t i c F e ( 1 )

cyano-complexes, s i n c e t h e 1:2 r a t i o o f Q.S. h a s b e e n o b s e r v e d .

The s p e c i e s C o b s e r v e d i n t h e ESR s p e c t r a h a s been a t t r i b u t e d t o a p r o t o n a t e d one / 3 / . T h i s s p e c i e s i s formed i n s m a l l e r c o n c e n t r a t i o n s a s compared w i t h s p e c i e s A and B and i t i s p o s s i b l y f o r t h i s r e a s o n t h a t i t d o e s n o t m a n i f e s t i t s e l f i n t h e M.S.

Acknowledgements.- We a r e i n d e b t e d t o D r . U. Wagner f o r doped m a t e r i a l p r e p a r a t i o n , t o D r . R d e B i a s i and Mr. N.M. P i n h a l f o r a s s i s t a n c e i n t h e ESR measu- r e m e n t s .

R e f e r e n c e s

/ I / C a r i d e , A.O., Z a n e t t e , S . I . , Danon, J . , J . Chem.

Phys.

52

(1970) 4911.

/ 2 / Muniz, R.P.A., Vugman, N . V . , Danon, J., J . Chem.

Phys.

2

(1971) 1284.

/ 3 / Symons, M . C . R . , W i l k i n s o n , J . G . , J.C.S. D a l t o n (1972) 14.

/ 4 / J a i n , S.C., Reddy, K . V . , Reddy, T.Rs., J. Chem.

Phys.

62

(1975) 4366.

/ 5 / Root, K.D. J . , Symons, M.C.R., J. Chem. Soc. A (1968) 2366.

/ 6 / J a i n , S.C., W a r r i e r . A.V.R., S e h g a l , H.K., J.

Phys. C: S o l i d S t a t e Phys.

5

(1973) 193.

/ 7 / Greenwood, N . N . , Gibb, T.C., "MGssbauer S p e c t r o - scopy", (Chapman and H a l l . London) 197 1 .

/ 8 / Wagner, F.E., P o t z e l , W . , Wagner, U., Schmidtke, H . H . , Chem, Phys. f? (1974) 284.