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Submitted on 1 Jan 1979
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STATIONARY AFTERGLOW STUDY OF THE SINGLY CHARGED ATOMIC IONS IN PURE AR
AND KR
M. Grössl, H. Helm, M. Langenwalter, T.D. Märk
To cite this version:
M. Grössl, H. Helm, M. Langenwalter, T.D. Märk. STATIONARY AFTERGLOW STUDY OF THE
SINGLY CHARGED ATOMIC IONS IN PURE AR AND KR. Journal de Physique Colloques, 1979,
40 (C7), pp.C7-51-C7-52. �10.1051/jphyscol:1979725�. �jpa-00219234�
JOURNAL D E Ph'YSIQUE CoZZoque C7, suppZdment au n07, Tome 40, JuiZZet 2979, nape C7- 51
STATIONARY AFTEROLOW STUDY OF ME m Y CHARGED ATOMIC IONS I N M E AR AND KR
M. Grossl, H. Helm, M. Langenwalter and T.D. Mark.
I n s t i t u t f. ExperimentaZphysik, Abt. F. exp &rn- n-nd PZasmaphysik, Leopold Franzens U n i v e r s i t t ~ t , A 6020 Innsbruck, Osterreich (Austria).
INTRODUCTION: The t r a n s p o r t phenomena and s t a t e than f o r t h e ground s t a t e i o n . I n r e a c t i o n mechanism of r a r e gas i o n s i n their a d d i t i o n , a strong dependence of the E t a s t a b l e p a r e n t g a s e s have been s t u d i e d with different i o n p o p u l a t i o n on t h e n e u t r a l impurity techniques by a l a r g e number of investigators: c o n c e n t r a t i o n has been observed. Hmever only The q u a n t i t a t i v e knowledge of t r a n s p o r t data one q u a n t i t a t i v e experimental r e s u l t about have been improved enormously by means of t h e r e a c t i v i t y of t h e 2~ i 6 n s t a t e i s
1/2
p r e c i s i o n d r i f t t u b e experiments s o t h a t r e p o r t e d s o f a r . Liu and Conway 19 75 report t h e o r i e s i n c l u d i n g f i n e s t r u c t u r e phencmena a n upper l i m i t , because t h e y cannot t o t a l l y may be t e s t e d . exclude s i d e r e a c t i o n s w i t h i m p u r i t i e s f o r
+ 2 t h e d e s t r u c t i o n frequency of in ( P
N e v e r t h e l e s s , t h e understanding of the reaction in in.
mechanisms i s s t i l l poor. For i n s t a n c e i n EXPERIMENTAL METHOD AND RESULTS: The i o n s argon v a l u e s given i n t h e l i t e r a t u r e for the were produced i n a pulsed hollowcath& glocv e f f e c t i v e 3-body r e a c t i o n r a t e c o e f f i c i e n t discharge and monitored w i t h a mass
f o r t h e conversion of t h e s i n g l y charged meter a s a f u n c t i o n of time a s d e s c r i b e d atomic i o n i n t o t h e dimer i o n elsewhere (Langemalter e t a1.1977). C a r e f u l
( 1 1 ~ r + + 2 A r + A r 2 + + A r a t t e n t i o n was payed t o minimize the inpurity l e v e l i n t h e g a s e s used. Measurements have s c a t t e r between 0.6 and 4 . 7 . 1 0 - ~ ~ a n ~ s - ~ .
been made a t n e u t r a l gas p r e s s u r e s between Hyatt and Kn-tubb 19 72 and Liu and Camay 1975
0 . 3 and 3 T o r r a t 297 K . a t t r i b u t e d an observed a n w l y i n the reaction
behaviour of t h e atomic argon i o n s t o t h e I n A r two d i f f e r e n t e x p o n e n t i a l decays of presence of i o n s i n t h e two f i n e S t ~ U c t u r e t h e Ar'-signal could be observed a t redu&
+ 2
s t a t e s , t h e ground s t a t e A r ( P3,2) and the m e t a s t a b l e s t a t e A ~ * ( ~ P , , ~ ) . A d e f i n i t e d i f f e r e n c e i n r e a c t i v i t y of t h e two f i n e
+ +
s t r u c t u r e s t a t e s of Ne and K r i n t h e i r p a r e n t g a s e s could be observed experimentally i n swarm experiments by Helm and E l f o r d 1978 A s a common evidence a l l m t i o n e d investigators observed a much lower d e s t r u c t i o n efficiency, due t o r e a c t i o n s f o r t h e m e t a s t a b l e i o n i c
gas p r e s s u r e s h i g h e r than 1.6 Torr, as is s h m in Fig. 1 f o r i n s t a n c e . From t h e measurements a t low gas p r e s s u r e s ( < 1 . 5 T o r r ) , where only one e x p o n e n t i a l decay has been observed, a v a l u e f o r t h e zero field nmbility of 1.55 a2/vs could be deduced i n very good agreement with d r i f t tube d a t a . Using t h i s v a l u e e f f e c t i v e 3-body r a t e c o e f f i c i e n t s f o r a l l p r e s s u r e s a r e c a l c u l a t e d and p l o t t e d versus gas pressure
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1979725
( F i g . 2 ) i n a s e m i - l o g a r i t h m i c diagram. The f u l l d o t s , which a r e r e l a t e d e i t h e r t o t h e s i n g l e e x p o n e n t i a l decay mode o r a t h i g h p r e s s u r e s t o t h e f a s t decay d u r i n g t h e e a r l y a f t e r g l o w , l i e between + l o % of a mean v a l u e of t h e r a t e c o e f f i c i e n t of 2 . 4 * 1 0 - ~ ~ c m ~ s - ' . E v i d e n t l y t h i s l o s s r a t e c o r r e s p o n d s t o t h e c o n v e r s i o n p r o c e s s ( 1 ) o f t h e 2 ~ 3 / 2 ground s t a t e i o n s . The open c i r c l e s , c o r r e s p o n d i n g
A r f in Ar
~ ~ ' 2 . 3 1 Torr h2 -
0.162cm2
tlrne I n
the a f t e r g l o w
F i g . 1 Measured time dependent Ar+ ion current a t high pressures: The double expnential decay curve f o r instance a t po = 2.31 Tarr.
t o t h e slow decay a t h i g h p r e s s u r e s , show a very s t r o n g p r e s s u r e dependence. T h i s slow decay p e r i o d i n t h e l a t e a f t e r g l o w may b e
+ 2
dominated by r e a c t i o n s o f A r ( i o n s f o r which H e l m and Varney 1978 proposed a r e a c t i o n model. F o r t h e i r model the effective 3-body r a t e c o e f f i c i e n t s v e r s u s pressure are
p, in Torr
0 1 2 3
-30 p
I I I4
J
0
-
0
'a
0 9 0
