- Email: [email protected]
Lifetime measurement of argon III levels
Volume29A, number4
PHYSICS LETTERS
LIFETIME
MEASUI~EMENT
OF
5May1969
AI~GON III
LEVELS
A. DENIS and M. DUFAY Laboratoire de Physique de l'Atmosph~re, Facult$ des Sciences de Lyon, France ($quipe de recherche associ$e au C. N. R. S.) Received 2 April 1969 The lifetime of some argon III levels has been measured using the 'beam foil technique'.
s$ sp
A b e a m of a r g o n i o n s w i t h 1.3 MeV e n e r g y , p a s s i n g t h ro u g h a thin c a r b o n foil (10 gg/cm~2), i s i o n i z e d and e x c i t e d . T h e i n t e n s i t y of a t r a n s i tion a f t e r the t a r g e t d e c r e a s e s e x p o n e n ti a l ly with the d i s t a n c e x as
sF
1= a exp(..x/vT) + ~ b n e x p ( - x / v ' f n) n
/"
t
w h e r e ~ is the l i f e t i m e of the u p p e r l e v e l and v the s p e e d of the ions. T h e second t e r m stands f o r the c a s c a d e s on the u p p e r l e v e l . T h e r a d i a t i v e de c a y of the t r a n s i t i o n s i s m e a s u r e d by m e a n s of a m o n o c h r o m a t o r with a p h o t o m u l t i p l i e r . We h a v e p r e v i o u s l y studied with this method the e x c i t e d l e v e l s in an i o n iz e d neon b e a m [ 1]. Most of the m u l t i p l e t s c l a s s i f i e d by C. M o o r e [2] a r e observoed, but the u n c l a s s i f i e d m u l t i p l e t 3509-3511 A i s c a l c u l a t e d f r o m e n e r g y l e v e l s given by C. M o o r e [3]. F u r t h e r m o r e , the v a r i a t i o n s with e n e r g y of the i n t e n s i t i e s of two unknown t r a n s i t i o n s (3639 and 4173 A) i n d i c a t e that they a r e due to A IH. T a b l e 1 g i v e s the l i f e t i m e of the u p p e r l e v e l s of the o b s e r v e d t r a n s i t i o n s . T h e a c c u r a c y of the m e a s u r e m e n t s i s about 10%. T h e e n e r g y l o s s , c a l c u l a t e d a f t e r the data of F a s t r u p et al. [4]
4
)S rl
4 Fig. 1. Partial term diagram for the measured transitions in A III. a m o u n t s to 70 keV. Th e m e a s u r e d l i f e t i m e s in neon HI [1] a r e a p p r o x i m a t e l y t w i c e as long as in ar g o n HI f o r t r a n s i t i o n s between h o m o l o g o u s s t a t e s in the two s p e c i e s . Such a b e h a v i o u r has to be r e l a t e d to p r e v i o u s r e g u l a r i t i e s pointed out by W i e s e and W e i s s [5]. 1. A. Denis, Compt. Rend. 268 (1969) 383, and to be published. 2. C. Moore, A multiplet table of astrophysical interest. N.B.S. (1945). 3. C. Moore, Atomic energy levels, N.B.S. (1958). 4. B. Fastrup, P. Hvelplund and C. A. Sautter, Mat. Fys. Medd. Dan. Vid. Selsk. 35, no. l0 (1966). 5. W.L.Wiese and A.W.Weiss, Phys.Rev. 175 (1968) 50. Table 1
Wavelength (~)
170
Transition
N° multiplet ref. 2
Upper level
Lifetime (ns)
3285
4s 5 S ° - 4 p 5p
1
4p 5p
2.4
3336
4s ~3D°- 4p' 3F
3
4p, 3F
2.5
3481
4s' 3D°- 4p' 3D
2
4pt 3D
2.6
3509-11
4s 3 S ° - 4 p 3p
-
4p 3p
2.4
3639
unidentified
-
4173
unidentified
3.2 3.0
PHYSICS LETTERS
LIFETIME
MEASUI~EMENT
OF
5May1969
AI~GON III
LEVELS
A. DENIS and M. DUFAY Laboratoire de Physique de l'Atmosph~re, Facult$ des Sciences de Lyon, France ($quipe de recherche associ$e au C. N. R. S.) Received 2 April 1969 The lifetime of some argon III levels has been measured using the 'beam foil technique'.
s$ sp
A b e a m of a r g o n i o n s w i t h 1.3 MeV e n e r g y , p a s s i n g t h ro u g h a thin c a r b o n foil (10 gg/cm~2), i s i o n i z e d and e x c i t e d . T h e i n t e n s i t y of a t r a n s i tion a f t e r the t a r g e t d e c r e a s e s e x p o n e n ti a l ly with the d i s t a n c e x as
sF
1= a exp(..x/vT) + ~ b n e x p ( - x / v ' f n) n
/"
t
w h e r e ~ is the l i f e t i m e of the u p p e r l e v e l and v the s p e e d of the ions. T h e second t e r m stands f o r the c a s c a d e s on the u p p e r l e v e l . T h e r a d i a t i v e de c a y of the t r a n s i t i o n s i s m e a s u r e d by m e a n s of a m o n o c h r o m a t o r with a p h o t o m u l t i p l i e r . We h a v e p r e v i o u s l y studied with this method the e x c i t e d l e v e l s in an i o n iz e d neon b e a m [ 1]. Most of the m u l t i p l e t s c l a s s i f i e d by C. M o o r e [2] a r e observoed, but the u n c l a s s i f i e d m u l t i p l e t 3509-3511 A i s c a l c u l a t e d f r o m e n e r g y l e v e l s given by C. M o o r e [3]. F u r t h e r m o r e , the v a r i a t i o n s with e n e r g y of the i n t e n s i t i e s of two unknown t r a n s i t i o n s (3639 and 4173 A) i n d i c a t e that they a r e due to A IH. T a b l e 1 g i v e s the l i f e t i m e of the u p p e r l e v e l s of the o b s e r v e d t r a n s i t i o n s . T h e a c c u r a c y of the m e a s u r e m e n t s i s about 10%. T h e e n e r g y l o s s , c a l c u l a t e d a f t e r the data of F a s t r u p et al. [4]
4
)S rl
4 Fig. 1. Partial term diagram for the measured transitions in A III. a m o u n t s to 70 keV. Th e m e a s u r e d l i f e t i m e s in neon HI [1] a r e a p p r o x i m a t e l y t w i c e as long as in ar g o n HI f o r t r a n s i t i o n s between h o m o l o g o u s s t a t e s in the two s p e c i e s . Such a b e h a v i o u r has to be r e l a t e d to p r e v i o u s r e g u l a r i t i e s pointed out by W i e s e and W e i s s [5]. 1. A. Denis, Compt. Rend. 268 (1969) 383, and to be published. 2. C. Moore, A multiplet table of astrophysical interest. N.B.S. (1945). 3. C. Moore, Atomic energy levels, N.B.S. (1958). 4. B. Fastrup, P. Hvelplund and C. A. Sautter, Mat. Fys. Medd. Dan. Vid. Selsk. 35, no. l0 (1966). 5. W.L.Wiese and A.W.Weiss, Phys.Rev. 175 (1968) 50. Table 1
Wavelength (~)
170
Transition
N° multiplet ref. 2
Upper level
Lifetime (ns)
3285
4s 5 S ° - 4 p 5p
1
4p 5p
2.4
3336
4s ~3D°- 4p' 3F
3
4p, 3F
2.5
3481
4s' 3D°- 4p' 3D
2
4pt 3D
2.6
3509-11
4s 3 S ° - 4 p 3p
-
4p 3p
2.4
3639
unidentified
-
4173
unidentified
3.2 3.0