ION-INDUCED K-SHELL IONIZATION IN ELEMENTS 19≤Z≤39

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ION-INDUCED K-SHELL IONIZATION IN ELEMENTS 19 ≤ Z ≤ 39

P. Kotze, D. Mingay

To cite this version:

P. Kotze, D. Mingay. ION-INDUCED K-SHELL IONIZATION IN ELEMENTS 19 ≤ Z ≤ 39. Journal

de Physique Colloques, 1987, 48 (C9), pp.C8-673-C8-675. �10.1051/jphyscol:19879117�. �jpa-00227225�

JOURNAL DE PHYSIQUE

Colloque

C9,

supplBment au n012, Tome 48, dBcembre 1987

ION-INDUCED K-SHELL IONIZATION I N ELEMENTS 19 S Z S 39

P.B. KOTZE and D.W. MINGAY

Atomic Energy Corporation of South Africa Ltd. Private Bag X256, Pretoria 0001, South Africa

ABSTRACT

The r e l a t i v e t r a n s i t i o n p r o b a b i l i t i e s of c h a r a c t e r i s t i c K and K a X-rays produced by ion-beam bombardment were measured s y s t e m a t i c a l l y i n t h i n t a r g e t s f o r e l e m e n t s 1 9 2 Z 2 39. R e s u l t s f o r p r o t o n and a l p h a p a r t i c l e induced K /K, e m i s s i o n r a t e r a t i o s compare f a v o u r a b l y w i t h photon-induced d a t a , w t i l e t h e d e u t e r o n - i n d u c e d r e s u l t s d e v i a t e i n c e r t a i n Z r e g i o n s . I n t h e c a s e o f n i t r o g e n - i o n i m p a c t on Ti and V, t h e K , and KB l i n e s were found t o b e s h i f t e d a p p r o x i m a t e l y 45 eV and 90 eV, r e s p e c t i v e l y , r e l a t i v e t o t h e proton-induced s p e c t r a . Hartree-Fock c a l c u l a t i o n s show t h a t t h e o b s e r v e d s h i f t s r e s u l t from m u l t i v a c a n c y p r o d u c t i o n w i t h two o r more a d d i t i o n a l L - s h e l l v a c a n c i e s , w h i l e d o u b l e K-shell i o n i z a t i o n i s t o t a l l y r u l e d o u t .

INTRODUCTION EXPERIMENTAL METHOD

I n n e r - s h e l l i o n i z a t i o n p r o c e s s e s have enjoyed u n p r e c e d e n t e d a t t e n t i o n and c o v e r a g e i n r e c e n t y e a r s , b o t h t h e o r e - t i c a l l y [ l ] and e x p e r i m e n t a l l y 121.

The i n t e r e s t i n i n n e r - s h e l l p h y s i c s h a s been s t i m u l a t e d by t h e o r i e s which d e s c r i b e t h e i o n i z a t i o n phenomena, a s w e l l a s by a growing, body of e x p e r i - m e n t a l d a t a . The m a j o r i t y o f s u c h measurements have been performed f o r p r o t o n bombardment, and a s m a l l e r number f o r a l p h a - p a r t i c l e beams, w h i l e d e u t e r o n - and h e a v i e r ion-induced measurements a r e c o m p a r a t i v e l y r a r e . The most s u c c e s s f u l t h e o r e t i c a l p r e d i c t i o n s o f K B /K, r a t i o s f o r e l e m e n t s 10 5 Z 2 98 have been performed by S c o f i e l d 131, u s i n g a r e l a t i v i s t i c Hartree-Fock d e s c r i p - t i o n . I n c o n t r a s t t o X-ray e m i s s i o n g e n e r a t e d by e l e c t r o n o r p r o t o n e x c i t a t i o n , X-ray l i n e s produced by heavy-ion bombardment a r e s h i f t e d t o h i g h e r e n e r g i e s . T h i s c a n r e a d i l y b e u n d e r s t o o d i n t e r m s o f a d d i t i o n a l L - s h e l l v a c a n c i e s produced by heavy-ion impact.

The 3.75 MeV Van d e G r a a f f a c c e l e r a t o r and PIXE beam l i n e [ 4 1 a t t h e Atomic Energy C o r p o r a t i o n was used t o s t u d y t h e X-ray p r o d u c t i o n by beams o f p r o t o n s , d e u t e r o n s , a l p h a p a r t i c l e s and n i t r o g e n i o n s w i t h e n e r g i e s between 0.6 and 3.0 MeV. An i n t r i n s i c germanium d e t e c t o r h a v i n g a r e s o l u t i o n o f 1 5 3 eV a t 5.9 keV, was used t o d e t e c t X-rays, e m i t t e d from t a r g e t s w i t h t h i c k n e s s e s between 30 and 110 pg/cm2. Dynamic beam p u l s i n g backed by e l e c t r o n i c p i l e - u p r e j e c t i o n was used t o a f f e c t p i l e - u p s u p p r e s s i o n i n t h e X-ray s p e c t r a . Energy c a l i b r a - t i o n s were performed b e f o r e and a f t e r e a c h n i t r o g e n s p e c t r u m t o e n s u r e e n e r g y s t a b i l i l y t o w i t h i n

+

^{2 eV over}

t h e d u r a t i o n of t h e measurements.

RESULTS AND DISCUSSION

K / K Intensity Ratios

B a

The r e l a t i v e i n t e n s i t y r a t i o s f o r K B and K,, t r a n s i t i o n s a s measured f o r 2.4 MeV p r o t o n s , d e u t e r o n s and a l p h a p a r t i c l e s a r e shown i n F i g u r e 1 t o g e t h e r w i t h t h e t h e o r e t i c a l

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19879117

C9-674 JOURNAL DE PHYSIQUE

E N E R G Y ( k e V ) .20.

19.

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816.

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Figure

2 : K

X-ray spectra of T i r e s u l t i n g from proton and nitrogen bombardments.

Protons 'IDeuterons

.

Alpha particles

- Scofield

-

^-Photons

. . .

15 20 3 0 35 40

Figure

1:

Relative i n t e n - s i t y o f

K

t o

K

t r a n s i - t i o n s meahred For

2.4

MeV protons, deuterons and alpha p a r t i c l e s and com- pared with the t h e o r e t i c a l predictions of Seofie Zd

[ 3 1

and t h e photon-induced e x c i t a t i o n r e s u l t s of S l i v i n i s k i and B e r t

[ 5

I.

25

z

Figure

3:

Hartree-Fock

K

a d

K

X-ray

snergy s h i f t s for various 9leetrofi con-

figurations i n T i .

p r e d i c t i o n s o f S c o f i e l d and t h e photon- e x c i t a t i o n r e s u l t s o f S l i v i n i s k y and E b e r t [51. The s m a l l b u t w e l l - d e f i n e d d i p s i n t h e K R /K r a t i o s p r e d i c t e d a t Cr and Cu by S c o f i e l d a r e s e e n i n t h e e x p e r i m e n t a l r e s u l t s f o r p r o t o n s , d e u t e r o n s and a l p h a p a r t i c l e s . A major d i s c r e p a n c y is s e e n , which i s n o t u n d e r s t o o d , i n t h a t t h e d e u t e r o n - induced e x c i t a t i o n s l i e above b o t h p r o t o n - and alpha-induced r e s u l t s and photon-induced v a l u e s f o r z 5 26 and d r o p below t h e s e r e s u l t s f o r Z > 26.

The a n o m a l i e s o b s e r v e d a t Z = 24 ( C r ) and Z = 29 (Cu) c a n p o s s i b l y b e e x p l a i n e d by t h e e l e c t r o n "shake-off"

t h e o r y of Levinger [ 6 1 and C a r l s o n a l . 171.

-

MuZtivacancy Production in Ti and V T h i n t a r g e t s of T i and V were bombarded by 3.0 MeV ~ + 3 i o n s . R e l a t i v e t o t h e p r o t o n e x c i t a t i o n s a t 2.4 MeV, t h e K

,

l i n e s produced by n i t r o g e n bombardment were s h i f t e d h i g h e r by 49 eV f o r T i and by 40 eV f o r V. The K a l i n e s s h i f t e d h i g h e r by 9 1 eV f o r Ti and by 86 eV f o r V. The e x p e r i m e n t a l r e s u l t s f o r T i a r e shown i n F i g u r e 2. Hartree-Fock c a l c u - l a t i o n s were performed t o e s t i m a t e t h e e x p e c t e d s h i f t s of t h e K , and K

a

l i n e s a s a r e s u l t o f m u l t i v a c a n c y p r o d u c t i o n . D e t a i l s o f t h e c a l c u - l a t i o n s a r e g i v e n by Froese-Cischer [81. R e s u l t s f o r Ti can b e s e e n i n F i g u r e 3. The r e q u i r e m e n t o f a s i m u l t a n e o u s agreement f o r t h e K

,

^and

K

B

s h i f t p r o v i d e s a s t r i n g e n t t e s t f o r t h e p o s s i b l e c o n f i g u r a t i o n . The p r o d u c t i o n o f two o r more a d d i t i o n a l L - s h e l l v a c a n c i e s r e s u l t s i n a p p r o x i - mately t h e e n e r g y s h i f t s o b s e r v e d , w h i l e d o u b l e K-shell i o n i z a t i o n c a n b e r u l e d o u t c o m p l e t e l y .

CONCLUSIONS

The K B /Kcl i n t e n s i t y r a t i o s o b t a i n e d f o r b o t h p r o t o n and a l p h a p a r t i c l e induced e x c i t a t i o n s a r e i n good agreement w i t h b o t h photon-induced r e s u l t s and S c o f i e l d ' s c a l c u l a t i o n s . T h i s i n c l u d e s t h e s m a l l d i p s o b s e r v e d f o r e l e m e n t s Cr and Cu where s i n g l e 4 s e l e c t r o n s a r e l o o s e l y bound. I n t h e c a s e of n i t r o g e n - i n d u c e d e x c i t a t i o n s i t s h o u l d be n o t e d t h a t t h e c a l c u -

l a t i o n s p r o v i d e an e s t i m a t e o f t h e e x p e c t e d s h i f t s w h i l e more r i g o r o u s c a l c u l a t i o n s a r e n e c e s s a r y t o under- s t a n d more f u l l y t h e o r i g i n o f such s h i f t s .

REFERENCES

[ l ] Chen M H, Crasemann B, A t . Data Nucl. Data T a b l e s 33 (1985) 217 [ 2 ] G e r e t s c h l g g e r M, Benka 0 , Phys.

Rev. A34 ( 1 9 8 6 ) 866

[ 3 1 S c o f i e l d J H, Phys. Rev. A9 (1974) 1041

141 Mingay D W, J o n k e r W D, Smith B J , pei-259 (1978)

r 5 ] ~ l i v i n i s k y V W, E b e r t P J , Phys.

Rev. A5 ( 1 9 7 2 ) 1 5 8 1

161 L e v i n g e r J W, Phys. Rev. 90 (1953) 11

171 C a r l s o n T A, Krause M 0 , ~ h y s . Rev. A140 ( 1 9 6 5 ) 1057

[ 8 1 F r o e s e - F i s c h e r C, The Hartree-Fock Method f o r Atoms (Wiley, New York, 1977)