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TIME-DEPENDENT PHENOMENA CAUSED BY THE EC DECAY IN Co2+ [Fe(CN)6]3-
Takayuki Kobayashi, Tetsuo Kitahara
To cite this version:
Takayuki Kobayashi, Tetsuo Kitahara. TIME-DEPENDENT PHENOMENA CAUSED BY THE EC DECAY IN Co2+ [Fe(CN)6]3-. Journal de Physique Colloques, 1980, 41 (C1), pp.C1-239-C1-240.
�10.1051/jphyscol:1980179�. �jpa-00219748�
JOURNAL DE PHYSIQUE Co//oque Cl
,
suppl&ment au n O 1, Tome 41, janvier 1980, page C1-239Takayuki Kobayashi and T e t s u o ~ i t a h a r a ' M e d i c a l C o l l e g e o f S h i g a , S h i g a , 5 2 0 - 2 1 J a p a n
+ ~ n s t i t u t e f o r C h e m i c a l R e s e a r c h , K y o t o U n i v . , K y o t o , 6 0 6 J a p a n
We have p r e v i o u s l y r e p o r t e d /1/ on t h e 0.03 and 0.4920.03 mm/sec, r e s p e c t i v e l y . time-dependence o f t h e l i n e w i d t h and r e c o i l - Those o f Fe2+ a r e - 0 . 9 5 5 . 0 6 and 2 . 1 6 s .06 less f r a c t i o n c f Fe2+ i n a 57c02+
[Fe (CN) I 3- sample, t h e s p e c t r a o f which were o b s e r v e d
by u s i n g t h e d e l a y e d - c o i n c i d e n c e t e c h n i q u e 0.95
-
/ 2 , 3 / . I n t h e p r e s e n t work, we a n a l y z e t h e r e s u l t s o b t a i n e d by t h e f u r t h e r meas- u r e m e n t s w i t h t h e same sample a s b e f o r e f o r s e v e r a l t i m e i n t e r v a l s a f t e r t h e EC d e c a y o f 5 7 ~ o .
The o b s e r v e d s p e c t r a a r e shown i n f i g u r e 1. The s p e c t r a were a n a l y z e d i n a c c o r d a n c e w i t h t h e method p r o p o s e d by one
0.95
-
o f t h e a u t h o r s (T.K.) / 4 / , i n which a com- p o n e n t peak i n t h e s p e c t r u m i s c o n s i d e r e d as a c o n v o l u t i o n o f a G a u s s i a n a n d a t i m e -
0.95
-
f i l t e r i n g peak d e v e l o p e d by Hamermesh /5/
I I
a n d H a r r i s /6/. The p a r a m e t e r s e s t i m a t e d
-: -\ -\ i 1 2
Velocity i rnm/sec I
by t h e l e a s t - s q u a r e s f i t t i n g a r e l i s t e d i n F i g . 1 : S p e c t r a w i t h a n d w i t h o u t c o i n c i - table I. The IS and QS of Fe3+ are -0.34+ d e n c e . The s o l i d c u r v e s a r e l e a s t - s q u a r e s
f i t s t o t h e e x p e r i m e n t a l d a t a .
T a b l e I : bl6ssbauer p a r a m e t e r s
Fe 3+ Fe 2+
Delay I n t e r v a l
:
(MeanTimel
:
A:
I n t e n s i t y:
4:
I n t e n s i t y:
(mm/sec):
( %( n s e c ) (mm/sec)
i
( % I20-40 ( 2 9 . 8 )
:
0 . 6 7 5 0.14:
7 4 . 1 5 4 . 2:
0 . 7 5 2 0 . 2 5:
2 5 . 9 2 4 . 7 40-60 ( 4 9 . 8 ):
1 . 2 1 2 0.22:
8 2 . 5 2 4 . 7:
0 . 5 0 t 0 . 1 5:
1 7 . 5 5 2 . 2 60-100 ( 7 9 . 1 ):
1.192
0.14:
79.72
3 . 1:
0 . 3 12
0.13:
20.35
3.7100-224 (153)
:
1.15+
0.34:
77.02
7.2:
0.222
0.06:
23.05
2.6Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1980179
c
1-240 JOURNAL DE PHYSIQUEm / s e c , r e s p e c t i v e l y . The c o i n c i d e n c e spec- t r a were a n a l y z e d by f i x i n g t h e peak p o s i - t i o n s . The p a r a m e t e r h i s t h e h a l f - w i d t h o f t h e Gaussian t e r m b e i n g t h e measure of t h e e f f e c t o f t h e time-independent n u c l e a r e n v i r o n m e n t a l inhomogeneity and t h e r e l a x a - t i o n phenomena. From t a b l e I , w e can s e e t h a t t h e v a l u e o f A o f ~ e decreasies w i t h ~ + t i m e , w h i l e we do n o t r e c o g n i z e any s i g n i f - i c a n t v a r i a t i o n o f t h e v a l u e s o f A ,of Fe 3+
e x c e p t f o r t h e v a l u e i n (20-40)-nsec d e l a y i n t e r v a l . The r e l a t i v e i n t e n s i t y o f Fe 2+
d e c r e a s e s i n i t i a l l y and a f t e r t h a t i n c r e a s e s g r a d u a l l y w i t h t i m e .
A s e x p l a i n e d i n t h e p r e v i o u s r e p o r t / I / , t h e i n c r e a s e of t h e . i n t e n s i t y o f Fe 2 -b l i n e s can be u n d e r s t o o d by t h e i n c r e a s e of t h e r e c o i l l e s s f r a c t i o n o f ~ e w i t h t i m e . ~ + The l a r g e r v a l u e o f t h e i n t e n s i t y i n
(20-40)-nsec i n t e r v a l t h a n t h e v a l u e i n t h e o t h e r i n t e r v a l s may be due t o t h e e f f e c t o f t h e i n t r a m o l e c u l a r e l e c t r o n t r a n s f e r from
~ e formed by t h e decay o f 5 7 ~ o ~ + t o a f e r r i - c y a n i d e i o n / 1 , 7 / . The r e s u l t s o b t a i n e d by t h e p r e s e n t measurements s u p p o r t t h e e x p l a - n a t i o n i n o u r p r e v i o u s r e p o r t . ~ e i o n s ~ + a r e formed by t h e decay of 5 7 ~ o a t t h e 8c p o s i t i o n s o f t h e s p a c e group Fm3m/Oh and 5 i n t e r a c t w i t h t h e i r s u r r o u n d i n g s more weakly t h a n i o n s a t t h e ( 0 , 0 , 0 ) p o s i t i o n . T h i s l o o s e bonding o f Fe 2+ i o n s w i t h t h e i r s u r - r o u n d i n g s i s r e s p o n s i b l e f o r t h e i n c r e a s e o f A and t h e i n c r e a s e o f t h e i h t e n s i t y o f ~ e ~ +
w i t h t i m e . We c a n n o t e x p l a i n t h e s m a l l Gaussian w i d t h A o f ~ e i n (20-40) - n s e c ~ + i n t e r v a l . However, t h e a p p r o x i m a t e l y con- s t a n t v a l u e o f h i n t h e o t h e r i n t e r v a l s can be p r o b a b l y a t t r i b u t e d t o t h e i n h e r e n t
c h a r a c t e r i s t i c o f t h e sample c r y s t a l , a s e x p l a i n e d i n r e f . 1. Assuming t h a t h
changes w i t h mean t i m e 'i a s A =a+bexp
(-S/T)
( a and b a r e c o n s t a n t s ) , t h e r e l a x a t i o n t i m e T was e s t i m a t e d t o be 30526 n s e c . I n f i g u r e 2 t h e Gaussian w i d t h A o f F,e2+ a r e p l o t t e d v s mean t i m e .
Mean Time Insecl
F i g . 2 : Gaussian w i d t h A p l o t t e d v s mean t i m e . The f i t i s shown by t h e s o l i d c u r v e .
I n t h e p r e s e n t s t a g e o f s t u d y , i t i s n o t c l e a r why t h e l i n e w i d t h d e c r e a s e s w i t h t i m e more r a p i d l y t h a n a s e x p e c t e d from t h e t i m e - f i l t e r i n g t h e o r y / 5 , 6 / . However i f t h e l i n e w i d t h i s i n v e s t i g a t e d i n more d e t a i l , it w i l l g i v e u s v a l u a b l e informa- t i o n s on t h e a f t e r e f f e c t .
R e f e r e n c e s
/1/ Kobayashi, T . , e t a l . , J . Physique C o l l o q .
40
(1979) C2-411./2/ Hoy, G. R . , e t a l . , "M6ssbauer E f f e c t Methodology", I . J . Gruverman e d . ,
(Plenum P r e s s , New York) 1971, p . 109.
/3/ Kobayashi, T. and Shimizu, S., Phys.
L e t t .
54A
(1975) 311./ 4 / Kobayashi, T., e t a l . , J . Physique C o l l o q .
40
(1979) C2-415./5/ Lynch, F. J , , e t a l . , Phys. Rev.
120
(1960) 513.
/6/ H a r r i s , S . M., Phys. Rev.
124
(1961) 1178./7/ Alekseev, V. P . , e t a l . , JETP L e t t .
16
(1972) 43.