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XUV EMISSION FEATURES FROM THE
LIVERMORE SOFT X-RAY LASER EXPERIMENTS
M. Eckart, J. Scofield, A. Hazi
To cite this version:
M. Eckart, J. Scofield, A. Hazi. XUV EMISSION FEATURES FROM THE LIVERMORE SOFT X-RAY LASER EXPERIMENTS. Journal de Physique Colloques, 1988, 49 (C1), pp.C1-361-C1-364.
�10.1051/jphyscol:1988178�. �jpa-00227592�
JOURNAL DE PHYSIQUE
C o l l o q u e C 1 , S u p p l 6 m e n t au n03, Tome 4 9 , Mars 1 9 8 8
XUV EMISSION FEATURES FROM THE LIVERMORE SOFT X-RAY LASER
EXPERIMENTS( )
M.J. ECKART, J . H . SCOFIELD and A.U. HAZI
Lawrence Livermore National Laboratory, Livermore, C A 94550, U.S.A.
A b s t r a c t .
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The measured w a v e l e n g t h s i n t h e s o f t x-ray r e g i o n f o r 3p t o 3 s and 3d t o 3p t r a n s i t i o n s i n neon-, sodium-, and magnesium-like s e l e n i u m a r e p r e s e n t e d . The e x p e r i m e n t a l r e s u l t s f o r t h e neon-like i o n s a r e compared t o t h e o r e t i c a l wavelength v a l u e s a n d w i t h v a l u e s e x t r a p o l a t e d a l o n g t h e i s o e l e c t r o n i c s e q u e n c e . The i o n s were c o n t a i n e d i n a plasma h e a t e d i n a l i n e - f o c u s o f a Nd-glass l a s e r . The measurements were made w i t h a time-gated m i c r o c h a n n e l - p l a t e - i n t e n s i f i e d g r a z i n g i n c i d e n c e s p e c t r o g r a p h .E x p e r i m e n t s a t t h e Lawrence Livermore N a t i o n a l L a b o r a t o r y have s u c c e s s f u l l y produced a m p l i f i e d s t i m u l a t e d e m i s s i o n i n neon-like i o n s o f s e l e n i u m , y t t r i u m , and molybdenum c o n t a i n e d i n plasmas h e a t e d i n t h e l i n e f o c u s o f Nd-glass l a s e r s . l s 2 As a n i n t e g r a l p a r t o f t h e s e e x p e r i m e n t s , t h e r e have b e e n measurements, i n t h e s o f t x-ray r e g i o n , o f t h e s p e c t r u m produced by t r a n s i t i o n s between t h e nu3 s t a t e s , and a l s o o f t h e x-ray s p e c t r a due t o t h e n=3 t o n=2 t r a n s i t i o n s . A s a p a r t o f t h i s e f f o r t , we have i d e n t i f i e d and measured t h e w a v e l e n g t h s o f t h e n=3 t o n=3 t r a n s i t i o n s i n neon-, sodium-, and magnesium-like i o n s o f Se. Y , and Mo. We p r e s e n t h e r e t h e measured v a l u e s f o r t h e neon-, sodium-, and magnesium-like t r a n s i t i o n s i n s e l e n i u m .
Measurements i n t h e s o f t x-ray r e g i o n were o b t a i n e d w i t h two time-gated m i c r o c h a n n e l - p l a t e - i n t e n s i f i e d g r a z i n g i n c i d e n c e s p e c t r o g r a p h s , o n e p o s i t i o n e d t o l o o k a l o n g t h e plasma column a x i s and t h e o t h e r a t a n a n g l e t o i t . Time g a t i n g i s accomplished by sub-200ps s w i t c h i n g of t h e m i c r o c h a n n e l - p l a t e b i a s v o l t a g e i n a m i c r o s t r i p geometry.l The d i s p e r s i o n o f t h e i n s t r u m e n t was c a l i b r a t e d by
m u l t i p l e h i g h - r e s o l u t i o n e x p o s u r e s o f known s p e c t r a f e a t u r e s of O I V , OV. N I V , and A l I V from a m i n a t u r e 2-pinch. Non-linear l e a s t - s q u a r e s f i t t i n g was used t o d e t e r m i n e l i n e p o s i t i o n s r e p o r t e d h e r e t o 2.021.
I n c l u d i n g d a t a t a k e n i n 1984, around 200 s p e c t r a have been d i g i t i z e d . F i g u r e 1 shows a good r e s o l u t i o n s p e c t r a t a k e n from a 1 c e n t i m e t e r column o f s e l e n i u m plasma. Under l a s i n g c o n d i t i o n s , t h e on-axis s e c t r a o b t a i n e d from t a r g e t s o f two
9
c e n t i m e t e r s and l o n g e r a r e dominated by f i v e 2 s 2p53p
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2 ~ ~ 2 ~ 5 3 s l a s i n g l i n e s . 1 S p o n t a n e o u s e m i s s i o n l i n e s coming from neon-, sodium-, andmagnesium-like i o n s a r e o b s e r v e d i n t h e o f f - a x i s s p e c t r a and as a component o f t h e o n - a x i s s p e c t r a . A s m a l l number o f f l u o r i n e - l i k e l i n e s have a l s o been t e n t a t i v e l y i d e n t i f i e d i n t h e s e l e n i u m s p e c t r u m . A l i s t i n g o f t h e sodium-like s e l e n i u m l i n e s a r e g i v e n i n t a b l e 1 and compared w i t h o t h e r measurements and i s o e l e c t r o n i c f i t s t o t h e l i n e p o s i t i o n s .
The i d e n t i f i c a t i o n of most o f t h e e x p e c t e d neon-like e m i s s i o n l i n e s h a s been a s s u r e d by c a r r y i n g o u t r e l a t i v i s t i c m u l t i c o n f i g u r a t i o n Hartree-Fock c a l c u l a t i o n s and e x t r a p o l a t i n g t h e small s y s t e m a t i c d i f f e r e n c e s between t h e o r y and measurements a t l o w e r a t o m i c numbers ( 2 ' s from 1 4 t h r o u g h 28) t o t h e i o n s o f c u r r e n t i n t e r e s t . The d i f f e r e n c e between t h e c a l c u l a t e d and measured t r a n s i t i o n e n e r g i e s have been f i t t o t h e form:
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("Work performed under t h e auspices o f t h e U S Department o f E n e r g l by t h e Lawrence Livermore National Laboratory under contract W-7405-ENG-48
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1988178
C1-362 JOURNAL
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PHYSIQUES o f t X-Ray Selenium Spectrum
r r
WAVELENGTH (i)
F i g . 1. On a x i s spectrum o f 1 c e n t i m e t e r column o f selenium plasma t a k e n w i t h t h e McPigs time g a t e d s p e c t r o m e t e r . The f e a t u r e a t 173 A i s due t o oxygen. The o t h e r f e a t u r e s a r e due t o magnesium-, sodium-, neon- and f l u o r i n e - l i k e selenium.
There is e x c e l l e n t agreement between t h e e x t r a p o l a t e d l i n e p o s i t i o n s and t h o s e measured. The p r e s e n t measurements i n S e , Y , and Mo and o t h e r r e c e n t measurements i n N i and CUT, Cu and Cie8, and S r by J.F. Wyart and h i s coworkers a t Orsay
e x t e n d t h e r a n g e of 2 o v e r which t h e neon-like n=3 t o 3 s p e c t r a have been observed.
Table 1. Sodium-like selenium wavelengths i n Angstroms.
I s o e l e c t r o n i c f i t s
I
Experimental v a l u e s Ref. 3 Ref. 41
Ref. 5 Ref. 6 p r e s e n texperiment
3 ~ 1 1 2
-
3d312 156.442 156.451 156.468 156.485 156.463 ~ 3 1 2
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3d512 174.076 174.101 174.118 174.124 174.103p312
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3d3/2 178.591 178.611 178.643 178.622 178.6439112
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3 ~ 3 1 2 200.992 201.019 201.07 201.060 201.0839112
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3 ~ 1 1 2 239.088 239.124 (239.23) 239.161 239.22Two f a c t o r s , i n a d d i t i o n t o wavelength p o s i t i o n , have been t a k e n i n t o a c c o u n t i n making t h e l i n e assignments. We have compared t h e l i n e s t r e n g t h s w i t h
t h e o r e t i c a l p r e d i c t i o n s f o r t h e i n t e n s i t i e s and t h e s y s t e m a t i c v a r i a t i o n o f t h e i n t e n s i t i e s of l i n e s from t h e same i o n i c c h a r g e w i t h changing plasma c o n d i t i o n s . Other t h a n t h e l a s i n g l i n e s and t h o s e o r i g i n a t i n g from s t a t e s having allowed x-ray t r a n s i t i o n s t o t h e ground s t a t e , t h e s t r e n g t h s o f t h e spontaneous e m i s s i o n l i n e s f o l l o w r o u g h l y t h e g f v a l u e of t h e corresponding t r a n s i t i o n s . The s y s t e m a t i c v a r i a t i o n of t h e l i n e i n t e n s i t i e s w i t h plasma c o n d i t i o n s a l l o w s t h e s e p a r a t i o n o f l i n e s from d i f f e r e n t i o n i c charge and t h e i d e n t i f i c a t i o n o f t h e neon-like l i n e s w i t h 2s h o l e s f o r which r e l a t i v e l y l i t t l e p r e v i o u s d a t a e x i s t .
The p r e s e n t a b i n i t i o c a l c u l a t i o n s u s e t h e r e l a t i v i s t i c m u l t i c o n f i g u a t i o n Hartree-Fock code by Grant and h i s coworkers.9 The energy v a l u e s f o r most o f t h e l e v e l s a r e i n s e n s i t i v e t o t h e b a s i s s t a t e s used i n t h e c a l c u l a t i o n . The J=0 even s t a t e s , though, show v a r i a t i o n s around 1.5eV w i t h d i f f e r e n t c h o i c e s o f b a s i s s t a t e s . We have n o t y e t o b t a i n e d convergence f o r a t e r m - s p e c i f i c o p t i m a l l e v e l c a l c u l a t i o n f o r t h e 2 ~ 5 1 1 2 3p112 s t a t e . We h e r e f o l l o w Cogordan and
coworkerslG and used t h e a v e r a g e - l e v e l o p t i o n f o r t h e J=O e v e n - p a r i t y e x c i t e d s t a t e s . The e x t r a p o l a t e d energy v a l u e s a r e i n s e n s i t i v e t o t h e a b i n i t i o d a t a s e t .
Table 2. Wavelengths i n Ingstroms f o r observed t r a n s i t i o n s o f neon-like
selenium. S t a t e s a r e l a b e l e d by major j j components, t h e vacancy i n t h e n=2 s h e l l i s l i s t e d f i r s t . The l a s i n g t r a n s i t i o n s are marked by a and completely dominate t h e s p e c t r a f o r plasma columns o f 3 c e n t i m e t e r s o r g r e a t e r . L i n e s marked by a x a r e p r e d i c t e d t o be weakly a m p l i f i e d and i n some s h o t s show s t r e n g t h s l a r g e r t h a n t h o s e p r e d i c t e d by g f v a l u e s .
s t a t e # ' a l o w e r s t a t e u p p e r s t a t e e x p e r i m e n t e x t r a p o l a t e d a b i n i t i o
vac
.
J vac. Jx 3 1 5 2 ~ 3 1 2 39112 1 2 ~ 1 1 2 3 ~ 1 1 2 0 113.4 113.14 6 20 2 ~ 3 1 2 3 ~ 1 1 2 1 2 ~ 3 1 2 36512 2 161.73 161.70 161.65 7 2 1 2 ~ 3 1 2 3 ~ 1 1 2 2 2 ~ 3 1 2 3d312 2 162.29 162.25 161.92 1 2 24 2 ~ 1 1 2 3 ~ 1 1 2 1 2p112 3d312 2 167.58 167.60 167.33 x 3 11 2 ~ 3 1 2 33112 1 2 ~ 3 1 2 3 ~ 3 1 2 0 168.67 7 168.67 167.70
a ) Using o n l y t h e d a t a f o r 2=26 and below. A f i t , e x c l u d i n g t h e p r e s e n t Se d a t a , but i n c l u d i n g t h a t f o r Mo and t h o s e f o r Cu and Ge from r e f . 9 g i v e s a v a l u e o f 182.44.
b) blended.
Table 3 p r e s e n t s t h e wavelengths o f t h e i d e n t i f i e d magnesium-like emission l i n e s . The t h e o r e t i c a l v a l u e s a r e t h o s e from t h e RAC code w r i t t e n by one o f t h e a u t h o r s (JHS) uhioh c a r r i e s o u t a r e l a t i v i s t i c configuation-interaction c a l c u l a t i o n u s i n g b a s i s s t a t e s from an average-configuation Hartree-Fock c a l c u l a t i o n .
R e s u l t s f o r t h e y t t r i u m and molybdenum s p e c t r a w i l l be g i v e n i n t h e f u t u r e . Table 3. Magnesium-like selenium wavelengths i n 8ngstroms.
J1 J2 a b i n i t i o p r e v i o u s exp. t h i s e x p e r i m e n t RAC code r e f . 11
3s3p-3s3d 0 1 139.7 140.85 a
1 2 142.3 143.36 a 143.12
144.14 s e v e r a l l i n e s p r e d i c t e d 146.90
i n t h e r e g i o n 147.64
a C a l c u l a t e d v a l u e s
b r e s o l v a b l e blend w i t h neon-like l i n e s
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