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Mean lives of some excited levels in N II – N IV
Vo|ume 32A, number 5
PHYSICS
LETTERS
c a u s e s that an e x p r e s s i o n p r o p o r t i o n a l to the r . h . s , of (5) a p p e a r s in the v e l o c i t y e q u a t i o n (6), w h i l e the t r a n s i t i o n r a t e in (5) b e c o m e s p r o p o r h o n a l to ( v d - Vc )2. U s i n g t h e d e f i n i t i o n s m ~ = ~ = 8 E - ~~ p a n d m ~ - = ~E J ,~p and the e x p h"c l"t
pot ~ pot , c f o r m of the p o t e n h a l e n e r g y Epo t for an i n t e r a c h n g B o s e s y s t e m , one s h o w s [5] that a l s o the v e l o m t y i n d e p e n d e n t t e r m s m (3) and (4) a g r e e f o r Pc 'P <" 1, whxch i s v a h d n e a r T k. ~ c t u r n s out to be z e r o in t h i s h m i t , and U = /~m. A g r e e m e n t b e t w e e n F r D h l i c h ' s e q u a t i o n (4) and K h a l a t m k o v ' s e q u a t m n (3 c o m b i n e d w i t h 2b) c a n , h o w e v e r , not be o b t a i n e d as long a s the e x t r a t e r m in eq. (2b) ~s f i n i t e , i . e . as long a s the t r a n -
MEAN
LIVES
OF
SOME
EXCITED
10 August 1970
s i t i o n r a t e , g i v e n in eq. (5), i s n o n - v a n i s h i n g . In c o n c l u s i o n it i s shown that P i t a e v s k i i ' s t h e r m o - d y n a m i c t h e o r y and F r b h l i c h ' s m i c r o s copically demved descriphon are equivalent near T;~, if the k i n e h c c o e f f i c i e n t A i s t a k e n to be purely imaginary.
References [1] L. P. Pltaevskn, Soy. Phys. J E T P 8 (1959) 282. [2] I M. Kha[atmkov, Sov. Phys. J E T P 30 {1970) 268. [3] H. Fr6hHch, Phys. kondens. Materle 9 (1969) 350. [4] G.J. Hy[and and G. Row[ands, Phys. Letters 30A (1969) 222. [5] H. Haug and K. Weiss, to be pubhshed.
LEVELS
IN
NII
N IV
J . A. K E R N A H A N , E . H . P I N N I N G T O N and C. C. LIN Department of Physws, University of Alberta, Edmonton 7, Canada. Received 2 June 1970
Beam-foil measurements of radiative lifehmes have been made for levels of N II - N IV.
We h a v e r e i n v e s t i g a t e d the b e a m - f o i l s p e c t r u m of n i t r o g e n in the w a v e l e n g t h r a n g e 3000 - 5600 A. R a d i a t i v e l i f e t i m e s w e r e o b t a i n e d f o r l e v e l s in N I I - N I V i n c l u d i n g s e v e r a l w h i c h had p r e v i o u s ly b e e n u n r e p o r t e d . N i t r o g e n i o n s w i t h e n e r g i e s b e t w e e n 0.8 - 1.8 MeV w e r e f i r e d t h r o u g h a c a r b o n f o i l , the r a d i a tion d o w n s t r e a m of the f o i l b e i n g a n a l y s e d and d e t e c t e d u s i n g a Spex 3,/4 m e t r e E b e r t s p e c t r o m e t e r f i t t e d with an E M I 6256S p h o t o m u l t i p l i e r . Full experimental details are available elsew h e r e [1]. We u s e d photon c o u n t i n g to o b t a i n d a t a for radiative decay curves. T a b l e 1 l i s t s the l i n e s o b s e r v e d f o r w h i c h l i f e t i m e s of the u p p e r l e v e l s c o n c e r n e d h a v e b e e n m e a s u r e d . T h e l i n e at 4290,~ i s l i s t e d by M o o r e [2] a s an u n c l a s s i f i e d N I I I t r a n s i t i o n , w h i l e F i n k [3] a s s i g n s the l i n e at 4 4 5 6 ~ to N I I I on the b a s i s of c h a r g e d e f l e c t i o n e x p e r i m e n t s . T h e o r e r ical lifetimes have been derived from transition
* Supported by the Province of Alberta and the National Research Council of Canada.
350
p r o b a b i l i t i e s l i s t e d in W i e s e et al. [4]. S t r i c t l y , t h e y a r e u p p e r l i m i t s only f o r the t h e o r e t i c a l lifetimes. When f i t t e d to a double e x p o n e n t i a l f u n c t i o n , the d a t a f o r 4607A g a v e l i f e t i m e s of 3.3 and 11.0 n s e c with e q u a l c o n t r i b u t i o n s to the i n i t i a l i n t e n s i t y . When f i t t e d to a s i n g l e e x p o n e n t i a l the v a l u e w a s 9.3 n s e c . At 4631A a d o u b l e fit g a v e 6.0 and 7.0 n s e c , the f o r m e r p r o v i d i n g the m a j o r c o n t r i b u t i o n to the i n i t i a l i n t e n s i t y , w h i l e a s i n g l e e x p o n e n t i a l fit y i e l d e d a v a l u e of 6.3 n s e c . S i n c e both l i n e s h a v e the s a m e 3p 3 p u p p e r s t a t e , c a s c a d i n g o r b l e n d i n g a p p e a r s to be an u n r e a l effect as single exponential fits give more cons i s t e n t r e s u l t s . A s i m i l a r s i t u a t i o n a r o s e f o r the l i n e at 4290A w h e r e a double e x p o n e n t i a l fit g a v e l i f e t i m e s of 1.5 and 10.7 n s e c w i t h e q u a l c o n t r i b u t i o n s to the i n i t i a l i n t e n s i t y , w h i l e a s i n g l e fit g a v e 9.0 n s e c . D e n i s et al. (5) a l l o w e d f o r c a s c a d i n g , u n l i k e L e w i s et al. (8), in o b t a i n i n g a lifetime value from this line. In g e n e r a l o u r r e s u l t s show good a g r e e m e n t w i t h t h e o r y and o t h e r w o r k e r s v a l u e s ; we f e e l t h e new v a l u e s in t a b l e 1 h a v e u s e f u l s i g n i f i c a n c e .
Volume 32A, number 5
PHYSICS L E T T E R S Table 1 Mean h v e s in N I I Measured wave length
Upper
10August 1970
NIV.
L i f e t i m e (10 -9 s e c )
level
]hls work
[5]
[6]
[7] [8]
:Iheory
3995 4042 4146 4176 4241
3plD 4f ~G 3p5S ° 4f I F 4f 3F
0.3 3.8* 6.0 5.4 3.2*
~- 0.6 ± 0.4 ~- 0.3 ± 0.3 ± 04
7.0 6.1 5.3 5.8 5.7 10.5 3.5 5.9 -
6.3 2.9 7.3 3.9 4.7
4433 4531 4607 ** 4631 ** 4992
4f 4f 3p 3p 3p
3D 1G 31) 3p 5pO
3.9* 4.3* 9.3 6.3 12.0
± 0.4 ± 0.4 ± 0.9 :~ 0.6 ± 1.2
-
5.4 3.9 9.5 9.5 13.0
5001 5005 5012
3F° 3F° 51)° 5F 5D
16.7 ± 0.8 14.0 ± 0.7 14.1 ~: 0.5
-
5179
3d 3d 3p 3d 3d
5535
3p 5D°
17.0 ± 0.7
NII
2.8 4.2
-
13.9
-
-
8.2 8.2 13.0 9.8 12.1
-
7.3 -
12.8
-
5.2 ± 0.4 17.4
NIII 3354 3367 3373 3771 4098
3p 4p 3p4p 3p~P 3p 4S 3p 2pO
5.3 5.4 7.3 8.9 4.7
4103 4200 4290 ** 4378 4456 **
3p 2 P ° 3p2D 5g 2G
5.0 2.2 1.5" 2.7" 2.4*
± :e ± ± :e
4510 4515 4860 4867
3p 3p 3d 3d
31.0 31.7 19.1 15.7
± 1.0 ~- 1.2 ± 1.0 ± 1.6
4D 4D 4F° 4F°
± 0.5 ~- 0.3 ± 0.7 ~- 0.5 ± 0.2 0.3 0.1 0.2 0.3 0.3
5.2 8.8 4.2 4.2 2.1 3.3 3.3 -
5.8 5.4 - 9.8 - 14.6 2.3
5.71 5.84 5.67 8.97 4.30
5.7 5.7 5.7 8.1 10.4
4.09 3.0 1.71 4.22 4.0 4.13
10.4 10.0 -
24.0 24.0 16.9 - 16.7
14.3 14.3 15.9 15.9
NIV 3479
3p 3 p o
11.5 ± 0.8
8.2
7.3
8.7 9.65
8.6
* Corrected for cascading ** See d l s c u s s m n m t e x t
References [1] J. A. K e r n a h a n , E . H . P i n n i n g t o n and C. C. L i n , J. Opt, Soc, Am, 60, No. 7 (1970). [2] C. E. M o o r e , A m u l t i p l e t t a b l e of a s t r o p h y s i c a l i n t e r e s t , Natl. B u r . Std. (U.S,) T e c h . Note 36, N o v e m b e r 1959. [3] U. F i n k , J. Opt. Soc. Am. 58 (1968) 937. [4] W. L. W i e s e , M . W . S m i t h and B. M. G l e n n o n , A t o m i c t r a n s i t i o n p r o b a b i l i t i e s , Vol. 1 (NSRDS-NBS 4, U.S. G o v ' t . , P r i n t i n g O f f i c e , W a s h i n g t o n D.C. 1966).
[5] A. D e n i s , J. D e s e s q u e l l e s , M. Dufay a nd M . - C . P o u l i z a c , C.R, A c a d. Sci. 266B (1968) 64; P r o c . B e a m - f o i l s p e c t r o s c o p y Conf., T u c s o n , A r i z o n a , N o v e m b e r 1967, ed. S. B a s h k i n (Gordon and B r e a c h , New Y o r k 1968). [6] E. H. P i n n i n g t o n and C. C. L i n , J . O p t . Soc. Am. 59 (1969) 717. [7] U. Fink, G.N. McIntire and S. Bashkin, J. Opt. Soe. Am. 58 (1968) 475. [8] M.R. Lewis, T. Marshall, E.H. Carnevale, F.S. Zimnoch and G. W. Wares, Phys. Rev. 164 (1967) 94,
351
PHYSICS
LETTERS
c a u s e s that an e x p r e s s i o n p r o p o r t i o n a l to the r . h . s , of (5) a p p e a r s in the v e l o c i t y e q u a t i o n (6), w h i l e the t r a n s i t i o n r a t e in (5) b e c o m e s p r o p o r h o n a l to ( v d - Vc )2. U s i n g t h e d e f i n i t i o n s m ~ = ~ = 8 E - ~~ p a n d m ~ - = ~E J ,~p and the e x p h"c l"t
pot ~ pot , c f o r m of the p o t e n h a l e n e r g y Epo t for an i n t e r a c h n g B o s e s y s t e m , one s h o w s [5] that a l s o the v e l o m t y i n d e p e n d e n t t e r m s m (3) and (4) a g r e e f o r Pc 'P <" 1, whxch i s v a h d n e a r T k. ~ c t u r n s out to be z e r o in t h i s h m i t , and U = /~m. A g r e e m e n t b e t w e e n F r D h l i c h ' s e q u a t i o n (4) and K h a l a t m k o v ' s e q u a t m n (3 c o m b i n e d w i t h 2b) c a n , h o w e v e r , not be o b t a i n e d as long a s the e x t r a t e r m in eq. (2b) ~s f i n i t e , i . e . as long a s the t r a n -
MEAN
LIVES
OF
SOME
EXCITED
10 August 1970
s i t i o n r a t e , g i v e n in eq. (5), i s n o n - v a n i s h i n g . In c o n c l u s i o n it i s shown that P i t a e v s k i i ' s t h e r m o - d y n a m i c t h e o r y and F r b h l i c h ' s m i c r o s copically demved descriphon are equivalent near T;~, if the k i n e h c c o e f f i c i e n t A i s t a k e n to be purely imaginary.
References [1] L. P. Pltaevskn, Soy. Phys. J E T P 8 (1959) 282. [2] I M. Kha[atmkov, Sov. Phys. J E T P 30 {1970) 268. [3] H. Fr6hHch, Phys. kondens. Materle 9 (1969) 350. [4] G.J. Hy[and and G. Row[ands, Phys. Letters 30A (1969) 222. [5] H. Haug and K. Weiss, to be pubhshed.
LEVELS
IN
NII
N IV
J . A. K E R N A H A N , E . H . P I N N I N G T O N and C. C. LIN Department of Physws, University of Alberta, Edmonton 7, Canada. Received 2 June 1970
Beam-foil measurements of radiative lifehmes have been made for levels of N II - N IV.
We h a v e r e i n v e s t i g a t e d the b e a m - f o i l s p e c t r u m of n i t r o g e n in the w a v e l e n g t h r a n g e 3000 - 5600 A. R a d i a t i v e l i f e t i m e s w e r e o b t a i n e d f o r l e v e l s in N I I - N I V i n c l u d i n g s e v e r a l w h i c h had p r e v i o u s ly b e e n u n r e p o r t e d . N i t r o g e n i o n s w i t h e n e r g i e s b e t w e e n 0.8 - 1.8 MeV w e r e f i r e d t h r o u g h a c a r b o n f o i l , the r a d i a tion d o w n s t r e a m of the f o i l b e i n g a n a l y s e d and d e t e c t e d u s i n g a Spex 3,/4 m e t r e E b e r t s p e c t r o m e t e r f i t t e d with an E M I 6256S p h o t o m u l t i p l i e r . Full experimental details are available elsew h e r e [1]. We u s e d photon c o u n t i n g to o b t a i n d a t a for radiative decay curves. T a b l e 1 l i s t s the l i n e s o b s e r v e d f o r w h i c h l i f e t i m e s of the u p p e r l e v e l s c o n c e r n e d h a v e b e e n m e a s u r e d . T h e l i n e at 4290,~ i s l i s t e d by M o o r e [2] a s an u n c l a s s i f i e d N I I I t r a n s i t i o n , w h i l e F i n k [3] a s s i g n s the l i n e at 4 4 5 6 ~ to N I I I on the b a s i s of c h a r g e d e f l e c t i o n e x p e r i m e n t s . T h e o r e r ical lifetimes have been derived from transition
* Supported by the Province of Alberta and the National Research Council of Canada.
350
p r o b a b i l i t i e s l i s t e d in W i e s e et al. [4]. S t r i c t l y , t h e y a r e u p p e r l i m i t s only f o r the t h e o r e t i c a l lifetimes. When f i t t e d to a double e x p o n e n t i a l f u n c t i o n , the d a t a f o r 4607A g a v e l i f e t i m e s of 3.3 and 11.0 n s e c with e q u a l c o n t r i b u t i o n s to the i n i t i a l i n t e n s i t y . When f i t t e d to a s i n g l e e x p o n e n t i a l the v a l u e w a s 9.3 n s e c . At 4631A a d o u b l e fit g a v e 6.0 and 7.0 n s e c , the f o r m e r p r o v i d i n g the m a j o r c o n t r i b u t i o n to the i n i t i a l i n t e n s i t y , w h i l e a s i n g l e e x p o n e n t i a l fit y i e l d e d a v a l u e of 6.3 n s e c . S i n c e both l i n e s h a v e the s a m e 3p 3 p u p p e r s t a t e , c a s c a d i n g o r b l e n d i n g a p p e a r s to be an u n r e a l effect as single exponential fits give more cons i s t e n t r e s u l t s . A s i m i l a r s i t u a t i o n a r o s e f o r the l i n e at 4290A w h e r e a double e x p o n e n t i a l fit g a v e l i f e t i m e s of 1.5 and 10.7 n s e c w i t h e q u a l c o n t r i b u t i o n s to the i n i t i a l i n t e n s i t y , w h i l e a s i n g l e fit g a v e 9.0 n s e c . D e n i s et al. (5) a l l o w e d f o r c a s c a d i n g , u n l i k e L e w i s et al. (8), in o b t a i n i n g a lifetime value from this line. In g e n e r a l o u r r e s u l t s show good a g r e e m e n t w i t h t h e o r y and o t h e r w o r k e r s v a l u e s ; we f e e l t h e new v a l u e s in t a b l e 1 h a v e u s e f u l s i g n i f i c a n c e .
Volume 32A, number 5
PHYSICS L E T T E R S Table 1 Mean h v e s in N I I Measured wave length
Upper
10August 1970
NIV.
L i f e t i m e (10 -9 s e c )
level
]hls work
[5]
[6]
[7] [8]
:Iheory
3995 4042 4146 4176 4241
3plD 4f ~G 3p5S ° 4f I F 4f 3F
0.3 3.8* 6.0 5.4 3.2*
~- 0.6 ± 0.4 ~- 0.3 ± 0.3 ± 04
7.0 6.1 5.3 5.8 5.7 10.5 3.5 5.9 -
6.3 2.9 7.3 3.9 4.7
4433 4531 4607 ** 4631 ** 4992
4f 4f 3p 3p 3p
3D 1G 31) 3p 5pO
3.9* 4.3* 9.3 6.3 12.0
± 0.4 ± 0.4 ± 0.9 :~ 0.6 ± 1.2
-
5.4 3.9 9.5 9.5 13.0
5001 5005 5012
3F° 3F° 51)° 5F 5D
16.7 ± 0.8 14.0 ± 0.7 14.1 ~: 0.5
-
5179
3d 3d 3p 3d 3d
5535
3p 5D°
17.0 ± 0.7
NII
2.8 4.2
-
13.9
-
-
8.2 8.2 13.0 9.8 12.1
-
7.3 -
12.8
-
5.2 ± 0.4 17.4
NIII 3354 3367 3373 3771 4098
3p 4p 3p4p 3p~P 3p 4S 3p 2pO
5.3 5.4 7.3 8.9 4.7
4103 4200 4290 ** 4378 4456 **
3p 2 P ° 3p2D 5g 2G
5.0 2.2 1.5" 2.7" 2.4*
± :e ± ± :e
4510 4515 4860 4867
3p 3p 3d 3d
31.0 31.7 19.1 15.7
± 1.0 ~- 1.2 ± 1.0 ± 1.6
4D 4D 4F° 4F°
± 0.5 ~- 0.3 ± 0.7 ~- 0.5 ± 0.2 0.3 0.1 0.2 0.3 0.3
5.2 8.8 4.2 4.2 2.1 3.3 3.3 -
5.8 5.4 - 9.8 - 14.6 2.3
5.71 5.84 5.67 8.97 4.30
5.7 5.7 5.7 8.1 10.4
4.09 3.0 1.71 4.22 4.0 4.13
10.4 10.0 -
24.0 24.0 16.9 - 16.7
14.3 14.3 15.9 15.9
NIV 3479
3p 3 p o
11.5 ± 0.8
8.2
7.3
8.7 9.65
8.6
* Corrected for cascading ** See d l s c u s s m n m t e x t
References [1] J. A. K e r n a h a n , E . H . P i n n i n g t o n and C. C. L i n , J. Opt, Soc, Am, 60, No. 7 (1970). [2] C. E. M o o r e , A m u l t i p l e t t a b l e of a s t r o p h y s i c a l i n t e r e s t , Natl. B u r . Std. (U.S,) T e c h . Note 36, N o v e m b e r 1959. [3] U. F i n k , J. Opt. Soc. Am. 58 (1968) 937. [4] W. L. W i e s e , M . W . S m i t h and B. M. G l e n n o n , A t o m i c t r a n s i t i o n p r o b a b i l i t i e s , Vol. 1 (NSRDS-NBS 4, U.S. G o v ' t . , P r i n t i n g O f f i c e , W a s h i n g t o n D.C. 1966).
[5] A. D e n i s , J. D e s e s q u e l l e s , M. Dufay a nd M . - C . P o u l i z a c , C.R, A c a d. Sci. 266B (1968) 64; P r o c . B e a m - f o i l s p e c t r o s c o p y Conf., T u c s o n , A r i z o n a , N o v e m b e r 1967, ed. S. B a s h k i n (Gordon and B r e a c h , New Y o r k 1968). [6] E. H. P i n n i n g t o n and C. C. L i n , J . O p t . Soc. Am. 59 (1969) 717. [7] U. Fink, G.N. McIntire and S. Bashkin, J. Opt. Soe. Am. 58 (1968) 475. [8] M.R. Lewis, T. Marshall, E.H. Carnevale, F.S. Zimnoch and G. W. Wares, Phys. Rev. 164 (1967) 94,
351