MÖSSBAUER RESONANCE IN 240Pu

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Submitted on 1 Jan 1979

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MÖSSBAUER RESONANCE IN 240Pu

G. Kalvius, D. Cohen, B. Dunlap, G. Shenoy

To cite this version:

G. Kalvius, D. Cohen, B. Dunlap, G. Shenoy. MÖSSBAUER RESONANCE IN 240Pu. Journal de

Physique Colloques, 1979, 40 (C2), pp.C2-634-C2-634. �10.1051/jphyscol:19792221�. �jpa-00218602�

JOURNAL DE PHYSIQUE Colloque C2. supplkment au n

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M ~ S S B A U E R RESONANCE I N 2 4 0 ~ u

G.M. K a l v i u s 'is , D. Cohen, B.D. Dunlap and G.K. Shenoy.

Argonne National Laboratory, Argonne, IZZinois 60439, U.S. A.

REsum4.- L ' e f f e t ~ 6 s s b a u e r a 4 t 4 o b s e r v 6 pour l a t r a n s i t i o n de 42.9keV du 2 * D ~ ~ . Avec une s o u r c e de

2 2 2

CmO, e t un a b s o r b a n t de Pu02 2 4.2K ou 5 77K on a t r o u v d une r a i e d e r 6 s o n a n c e u n i q u e e t l 4 g S r e - ment d l a r g i e . Le compos6 de p l u t o n y l (VI) pu02C,04 p r e s e n t e une i n t d r a c t i o n q u a d r u p o l a i r e l e Z q q l ⁼ 9 5 m / s . Aucun dgplacement i s o m d t r i q u e n ' a d t d d e t e c t 4 .

A b s t r a c t . - The M6ssbauer r e s o n a n c e of t h e 42.9keV t r a n s i t i o n i n 2 ' 0 ~h a s b e e n o b s e r v e d . For a ~

2 4 4 ~ m 0 2 s o u r c e ,and a Pu02 a b s o r b e r a t 4.2K and 77K a s l i g h t l y broadened s i n g l e r e s o n a n c e was found.

The p l u t o n y (VI) compound Pu02C20, showed a q u a d r u p o l e s p l i t t i n g o f l e Z q q I = 95mm/s. No isomer s h i f t s c o u l d be d e t e c t e d .

F i r s t measurements w i t h t h e 42.9keV. E2, 2+-+ 0 + t r a n s i t i o n i n 2 4 0 ~ u a r e r e p o r t e d . As s o u r c e s we used 2mg o f t h e a - p a r e n t 2 r r ~ m w i t h T1/2 = 18. ly.

Although t h e s p e c i f i c a c t i v i t y o f 2 4 ' ~ m i s 83mC/mg, i t s gamma r a y e m i s s i o n i s v e r y weak due t o t h e l a r - ge i n t e r n a l c o n v e r s i o n c o e f f i c i e n t (9 a 900) o f t h e 42.9keV t r a n s i t i o n . S o u r c e compound was CmOz which h a s t h e c u b i c f l u o r i t e s t r u c t u r e and i s t h u s e x p e c t e d t o show a s i n g l e e m i s s i o n l i n e . A b s o r b e r s were p r e p a r e d from 99.9% i s o t o p i c a l l y p u r e m a t e r i a l and had a t h i c k h e s s o f -60mg/crn2 o f * ' O P U . TWO d i f - f e r e n t compounds were i n v e s t i g a t e d : ( i ) %which a l s o c r y s t a l l i z e s i n t h e c u b i c f l u o r i t e s t r u c t u r e . The e l e c t r o n i c g r o u n d s t a t e of t h e PU" i o n i n a c u b i c c r y s t a l l i n e f i e l d i s a s i n g l e t . T h e r e f o r e no e l e c t r i c f i e l d g r a d i e n t o r m a g n e t i c h y p e r f i n e f i e l d i s e x , > e c t e d a t t h e Pu s i t e . S p e c t r a t a k e n a t 4.2K and 77K b o t h gave a s i n g l e L o r e n t z i a n r e s o n a n c e

p r e s e n t a c c u r a c y . The v a l u e deduced f o r t h e e l e c - t r i c f i e l d g r a d i e n t compares w e l l w i t h eq =

= +5x1018 v/cm2 found i n i s o e l e c t r o n i c n e p t u n y l (V) compounds / I / . No i s o m e r s h i f t l a r g e r t h a n 0 . 5 m / s c o u l d be d e t e c t e d between p u b + and p u 6 + . T h i s g i v e s a l i m i t o f ~ < r ~ > / < r ~ > <lo-' a s e x p e c t e d f o r p u r e r o t a t i o n a l e x c i t a t i o n s i n n u c l e i w e l l w i t h i n t h e r e g i o n o f s t r o n g d e f o r m a t i o n . The 42.9keV r e s o n a n c e i n 2 ' 0 ~h a s p r o p e r t i e s r a t h e r s i m i l a r t o t h e w e l l ~

e s t a b l i s h e d r e s o n a n c e i n 2 3 8 ~ . Although l i m i t e d i n r e s o l u t i o n i t h a s p r o v e n u s e f u l f o r h y p e r f i n e measu- r e m e n t s . S y s t e m a t i c i n v e s t i g a t i o n s o f h y p e r f i n e p a r a m e t e r s from U t h r o u g h Am a r e now p o s s i b l e , e . g . t h e s t u d y o f t h e e l e c t r i c f i e l d g r a d i e n t i n a c t i n y l compounds / 2 / .

R e f e r e n c e s w i t h a FWHM of -46rmnIs ( a f t e r c o r r e c t i o n f o r f i n i t e

/ I / See Dunlap, B. D . , and K a l v i u s , G.M. , i n "The a b s o r b e r t h i c k n e s s ) . T h i s number e x c e e d s by 20% t h e A c t i n i d e s : E l e c t r o n i c s t r u c t u r e and R e l a t e d minimum o b s e r v a b l e w i d t h a s d e i u c e d from t h e h a l f P r o p e r t i e s " . A.J. Freeman and J.B. Da-by. J r . ,

e d s . (Academic P r e s s , New York) 1974, p. 275 l i f e o f 0.16ns o f t h e 2+ s t a t e . ( i i ) Pu02CsOr, f o r a c o m p i l a t i o n of d a t a and r e f e r e n c e s . which i s a p l u t o n y l (VI) compound c o n t a i n i n g t h e / 2 / Dunlap, B.D. and K a l v i u s , G.M., 3 r d I n t . Conf.

LO-pu6+-01 group. The l i n e a r bond i n t h e p l u t o - o n E l e c t r o n i c S t r u c t u r e o f A c t i n i d e s , G r e n o b l e , F r a n c e (Aug. 1978).

n y l p r o d u c e s a n a x i a l e l e c t r i c f i e l d g r a d i e n t a t t h e Pu s i t e . The Mzssbauer s p e c t r u m a t 4.2K c o n s i s - t e d o f a broadened r e s o n a n c e w i t h weak s t r u c t u r e . A q u a d r u p o l e i n t e r a c t i o n of l e 2 q q l = (95?4)mm/s c o u l d b e e x t r a c t e d which g i v e s / e q l =

= ( 4 . 1 2 0 . 2 ) ~ 10" v/cm2. A d e t e r m i n a t i o n o f t h e s i g n o f t h e i n t e r a c t i o n was n o t p o s s i b l e w i t h t h e

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Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792221