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Submitted on 1 Jan 1980
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MÖSSBAUER INVESTIGATION OF
DEOXYMYOGLOBIN SINGLE CRYSTALS WITH POLARIZED γ-RAYS
H. Willems, H. Fischer, A. Trautwein, U. Gonser, F. Parak, Y. Maeda
To cite this version:
H. Willems, H. Fischer, A. Trautwein, U. Gonser, F. Parak, et al.. MÖSSBAUER INVESTIGATION
OF DEOXYMYOGLOBIN SINGLE CRYSTALS WITH POLARIZED
γ-RAYS. Journal de PhysiqueColloques, 1980, 41 (C1), pp.C1-487-C1-488. �10.1051/jphyscol:19801192�. �jpa-00219682�
JOURNAL DE PHYSIQUE Colloque C1, suppl&ment au n O 1, Tome 41, janvier 1980, page C1-487
MSSBAUER
INVESTIGATION OF DEOXYMYOGLOB IN SINGLE CRYSTALS W I T H POLAR1 ZED Y-RAYS H. Willems, H. Fischer, A. Trautwein, U. Gonser, F. Parak and+
Y. Maeda*Uniuersit8t des SaarZandes, 66 Saarbriicken, W-Germany.
+
Physik-Department, TU Wnchen, 8046 Garching, W-Germany.x Research Reactor I n s t i t u t e , Kyoto University, Osaka, Japan.
Deoxymyoglobin (MB) s i n g l e c r y s t a l s have been i n v e s t i g a t e d u s i n g p o l a r i z e d (and un- p o 1 a r i z e d ) r - r a y s . The e x p e r i m e n t a l v a l u e s o b t a i n e d w i t h u n p o l a r i z e d r a d i a t i o n were i n agreement w i t h o u r former work'. A s a p o l a r i z e d s o u r c e we u s e d c o S 7 (100 mCi) e m bedded i n @ - i r o n a t room t e m p e r a t u r e mag- n e t i z e d p e r p e n d i c u l a r t o t h e $ - r a y p r o p a - g a t i o n d i r e c t i o n . T h i s arrangement y i e l d s s i x l i n e a r p o l a r i z e d l i n e s , A , B ,
...,
F.S p e c t r a have been r e c o r d e d f o r d i f f e r e n t d i r e c t i o n s of t h e m a g n e t i z a t i o n
3
r e l a t i v t o t h e c r y s t a l a x i s b and f o r d i f f e r e n t a n g l e s of r o t a t i o n Y a r o u n d t h e b a x i s( F i g . 2 ) . Some of t h e s p e c t r a a r e shown i n F i g . 1 . The a b s o r b e r t r a n s i t i o n s a a n d 13,re- s u l t i n g from q u a d r u p o l e i n t e r a c t i o n , com- b i n e d w i t h t h e s i x e m i s s i o n l i n e s l e a d t o twelve a b s o r p t i o n l i n e s . From t h e computer f i t s we g o t i n t e n s i t y r a t i o s A O / A a
,
BO/Bg<a s a f u n c t i o n of t h e a n g l e
Y .
To d e t e r m i n e t h e EFG p a r a m e t e r s from t h e measured i n t e n s i t y r a t i o s a method on t h e b a s i s of t h e d e n s i t y m a t r i x formalism h a s been worked o u t . We e x p l i c i t l y c a l c u l a t e d
. A
t h e d e n s i t y m a t r i x
9a
f o r t r a n s i t i o n s i n pe5' n u c l e i . Using t h e f o r m u l a 2 f o r ;he r eA
s o n a n t l y a b s o r b e d i n t e n s i t y I = t r ( y e . 9 a ) ( i n t h e t h i n a b s o r b e r a p p r o x i m a t i o n ) where
ye
A i s t h e d e n s i t y m a t r i x of t h e s b u r c e r a - d i a t i o n , we d e r i v e t h e o r e t i c a l i n t e n s i t y r a t i o s f o r d i f f e r e n t p o l a r i z a t i o n s o f t h e s o u r c e r a d i a t i o n a s a f u n c t i o n o f t h e r o - t a t i o n a n g l e .Applied t o o u r e x p e r i m e n t a l d a t a t h e f o r - mulae l e a d t o a s y s t e m of e q u a t i o n s f o r
a n g l e s
a,,
[5,,
8, which depend on t h e EFG o r i e n t a t i o n r e l a t i v e t o t h e a x e s s y - stem ( x , y , z ) ( s . F i g . 2 ) , t h e asymmetrypa- r a m e t e r q and t h e s i g n of t h e main compo- n e n t V z Z of t h e EFG. Thus o n l y a manyfold o f s o l u t i o n s c a n b e o b t a i n e d ( F i g . 3 ) . T h i sa m b i g u i t y i s due t o t h e f a c t t h a t i n MB s i n g l e c r y s t a l s we have two i r o n atoms p e r u n i t c e l l , one atom b e i n g t r a n s f o r m e d i n t o t h e o t h e r by a 1 8 0 ' - r o t a t i o n around t h e b a x i s . I n t h e c a s e o f o n l y one atom p e r u n i t c e l l , w i t h p o l a r i z e d r a d i a t i o n t h e EFG pa- r a m e t e r s c o u l d be u n i q u e l y d e t e r m i n e d by r o t a t i o n around one a x i s whereas w i t h a n u n p o l a r i z e d s o u r c e one would need ( g e n e r a l - l y ) r o t a t i o n s around two n o n - c o l l i n e a r a x e s .
A s a consequence o f t h e t h e o r e t i c a l t r e a t - ment t h e i n t e n s i t y r a t i o s f o r u n p o l a r i z e d
3 - r a y s and f o r x - p o l a r i z e d x - r a y s a r e s t r i c t l y c o r r e l a t e d and t h e x - p o l a r i z e d ra- t i o s a r e c o n s t a n t ( w i t h v a l u e k ) f o r r o t a - t i o n s around t h e y a x i s , which i s i n o u r c a s e p a r a l l e l t o t h e b a x i s ( s . F i g . 2 ) . T h i s i s w e l l r e p r e s e n t e d by o u r e x p e r i - ments, b u t t h e measured v a l u e K=1.0'0.1 i s
d i f f e r e n t from t h e t h e o r e t i c a l l y e x p e c t e d v a l u e , which s h o u l d be 0.65 t o be c o n s i s - t e n t w i t h t h e i n t e n s i t y r a t i o s o b t a i n e d w i t h u n p o l a r i z e d r a d i a t i o n . The d i s c r e p a n - cy of t h e t h e o r e t i c a l and e x p e r i m e n t a l k v a l u e s i s o n l y s l i g h t l y improved by t a k i n g i n t o a c c o u n t a d e f i c i e n c y o f s o u r c e p o l a r i - z a t i o n , t h i c k n e s s e f f e c t s , a n g l e u n c e r t a i r r t i e s e t c . However, an e x p l a n a t i o n might be g i v e n by assuming t h a t a pronounced a n i s o - t r o p i c r e l a x a t i o n e f f e c t i s o p e r a t i v e s i - m i l a r t o o b s e r v a t i o n s made by Morup 3
.
R e f e r e n c e s :
1 . Gonser, U . , Maeda, Y . , T r a u t w e i n , A . , P a r a k , F . , Formanek, H . , Z . N a t u r f o r -
schung
a,
(1974) 2412. D a n i e l s , J . M . , Nucl. I n s t . Meth.
128,
(1975) 483
3. M$rup, S . , H y p e r f i n e I n t e r a c t i o n s
1,
(1976) 533
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19801192
C1-488 JOURNAL DE PHYSIQUE
- 8 -1
0
48
Velocity [ mm/s]
F i g . 1 : M i s t h e d i r e c t i o n of t h e s o u r c e m a g n e t i z a t i o n , b i s t h e t w o f o l d symmetry a x i s of t h e s i n g l e c r y s t a l . The a n g l e s g i - ven i n t h e p i c t u r e s p e c i f y t h e r o t a t i o n a- round t h e b a x i s . For a l l s p e c t r a , M and b -.
were p e r p e n d i c u l a r t o t h e r - r a y , and T was 7 7 K . Note t h a t t h e l i n e p o s i t i o n s a r e a l l
F i g . 2: Schematic of t h e o r i e n t a t i o n r e l a - t i o n s i n t h e e x p e r i m e n t s . 9 =250° c o r r e s - ponds t o f - r a y / / c , and J -340' t o t - r a y / / a ' .
90 -4
80
-
70-
-
i 60-h *
n -
-
50- n a# -
-
Cn; LO-
30-
F i g . 3: Manyfold of s o l u t i o n s o b t a i n e d by o u r t h e o r e t i c a l a n a l y s i s of t h e experimen- t a l d a t a . The a n g l e s
OEo, O 0 , Bmin(maxl d e s c r i b e t h e t r a n s f o r m a t i o n of t h e l a b o r a - t o r y system t o t h e EFG system i n t h e cas'e where t h e e x p e r i m e n t a l l y o b t a i n e d i n t e n s i -
t y r a t i o R=Il3/Ia f o r u n p o l a r i z e d r - r a y s i s minimal (maximal). The s o l i d l i n e s (un- primed a n g l e s ) c o r r e s p o n d t o Rmin=0.66, Rmax=1.18 and k=0.65, where k i s t h e con- s t a n t r a t i o f o r x - p o l a r i z e d r - r a y s . The measured v a l u e s were Rmin=0.67t0.07, Rmax=1.18~0.11 and k=1.0'0.11. I f we keep k = 1 . 0 t h e dashed l i n e s (primed a n g l e s ) a r e o b t a i n e d f o r Rmin=0.76 and Rmax=l.31.
S u p p o r t e d by Deutsche Forschungsgemein- s c h a f t
.
known from a p p r o p r i a t e c o m b i n a t i o n o f emmi- s s i o n l i n e s A,
