In the present work, the experimentally determined oscillator strengths of the 3p 2 P → nd D 2 (16 ≤ n ≤ 43) Rydberg transitions of lithium have been reported for the first time. The experiments were performed using two dye lasers simultaneously pumped by the second harmonic (532 nm) of an Nd:YAG laser, and the vapor containment and detection system was a thermionic diode ion detector. The first frequency-doubled dye laser excites the groundstate atoms to the 3p 2 P excited state at 325.35 nm, and the second dye laser was scanned up to the first ionization threshold. The f -values of the aforementioned transitions have been determined using the threshold value of the photoionization cross section (30 4.8 Mb) from the 3p 2 P excited state. A complete picture of the oscillator strengths from n 3 to 43 has been presented, including the previously known oscillator strength and determined in this work.

No abstract

No abstract

No abstract

D o c t o r o f P h i l o s o p h y o f t h e U n i v e r s i t y o f L n d i t s d e t u n i n g ( A ) f r o m t h e a t o m i c t r a n s i t i o n f r e q u e n c y (wQ ) . T h e l a s e r f i e l d i s a s s u m e d t o b e m o n o c h r o m a t i c a n d l i n e a r l y p o l a r i z e d . I t i s c o n s t a n t o v e r t h e c o l l i s i o n d u r a t i o n a n d i t s f r e q u e n c y i s s l i g h t l y d e t u n e d f r o m t h e a t o m i c t r a n s i t i o n f r e q u e n c y . T h e a t o m s a r e a s s u m e d t o f o l l o w c l a s s i c a l r e c t i l i n e a r p a t h s a n d o n l y u n d e r g o b i n a r y c o l l i s i o n s . T h e r e s o n a n c e i n t e r a c t i o n i s t a k e n t o b e t h e f i r s t o r d e r d i p o l e -d i p o l e i n t e r a c t i o n a c t i n g w i t h i n t h e g r o u n d a n d r e s o n a n c e l e v e l s o f a p a i r o f a t o m s w h o s er e s p e c t i v e a n g u l a r m o m e n t a a r e (Fg= 0) a n d (Fe = l ) . Q u a l i t a t i v e e x p l a n a t i o n s a r e o f f e r e d f o r t h e r e s u l t s o b t a i n e d . T h e y i n v o l v e s p l i t t i n g t h e H a m i l t o n i a n i n t o p a r t s t h a t r e p r e s e n t t h e f r e e e v o l u t i o n o f t h e s y s t e m a tt h e R a b i f r e q u e n c y , t h e " n o r m a l " r e s o n a n c e i n t e r a c t i o n , a n d t h e " p e r t u r b a t i v e " i n t e r a c t i o n r e s p o n s i b l e f o r o p e n i n g n e w s c a t t e r i n g c h a n n e l s d e p e n d i n g u p o n t h e r e l a t i v e s t r e n g t h s o f t h e r e s o n a n c e i n t e r a c t i o n ( R ) , t h e g e n e r a l i s e d R a b i f r e q u e n c y (O') a n d t h e r a t i o ( Q / A ) . T h e s e e x p l a n a t i o n s s a t i s f a c t o r i l y d e s c r i b e t h e m a j o r i t y o f t h e r e s u l t s o b t a i n e d . O t h e r p o s s i b l e e x p l a n a t i o n s a r e g i v e n w h e r e t h e s i m p l e p e r t u r b a t i o n t h e o r y i s i n a d e q u a t e .3 ACKNOWLEDGMENTS