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Photoinduced charge separation across surfactant interfaces of micelles and vesicles
280
Symposium Abstracts
CHENIS~TRY
RADIATION
72.
PNOTOINDUCED
CHARGE ~EPARATION OF MICELLES AND
ACROSS ~RFACTANT VESECLES~
INTERFACES
LARRY KEVAN Department
of Chemlstry~ Univereity Houston, Texas 77204-5641
of
Houston
The s t r u c t u r a l aepects controlling photoinduced charge s e p a r a t i o n of solutes i n m i c e l l e s and v e s i c l e s a r e b e i n g s t u d i e d t o o p t i m i z e t h e storage of light energy. E l e c t r o n s p i n r e s o n a n c e (ESR) i s used to detect the paramagnetic p h o t o l n d u c e d c a t i o n s and t o p r o b e t h e i r s u r r o u n d i n g s . I n t e r a c t i o n s between t h e p h o t o i n d u c e d c a t i o n and w a t e r as w e l l as o t h e r s t r u c t u r a l information can be studied by electron spin echo modulation ( E S E M ) which enables the determination of weaker e l e c t r o n - n u c l e a r hyperflne interactions than one n o r m a l l y d e t e c t s by ESR. Photolonizatlon of a solute in m i c e l l e s or vesicles requires electron transfer to or through the interface region. How modifications of this interface r e g i o n p r o v i d e s a p o t e n t i a l c o n t r o l mechanism f o r t h e p h o t o i o n i z a t i o n process w i l l be d i s c u s s e d i n c u r r e n t w o r k , l o c a t i o n c o n t r o l of electron donors and acceptors with respect to a micelle or vesicle interface are being i n v e s t i g a t e d by a d d i n g a l k y l c h a i n s o f variable length to such molecules. Alkylmethylviologens are proving effective for this purpose. ESEM e n a b l e s assessment of the Location relative to the mlcelle or vesicle interface.
73.
STUDY OF THEPJ~ALIZATION ANIONS IN POLAR LIQUIDS A.M.
Institute
RAITSIMRING, of
LENGTHS AND LIFETINES O F RI~)ICAL BY PNOTOINJECTION METHODS'"
A.I.
KALUGIN,
Chemical K i n e t i c s
V.V.
KONOVALOV
and C o m b u s t i o n , N o v o s i b i r s k
The method o f e l e c t r o n p h o t o i n j e c t l o n f r o m a m e t a l t o an e l e c t r o l y t e solution (PIMES) has been used t o s t u d y t h e dependences o f thermalizatlon lengths of s l o w e l e c t r o n s on t h e i r e n e r g i e s i n w a t e r and m e t h a n o l . The r a n g e o f maximum e n e r g i e s w i t h i n w h i c h t h e measurements w e r e u n d e r t a k e n was 0 . 2 - 5 eV and the r a n g e o f mean e n e r g i e s , 0 . 1 - 3 eV. The e n e r g y o f i n j e c t e d e l e c t r o n s was changed by v a r y i n g b o t h t h e p o t e n t i a l and t h e l i g h t wave l e n g t h which illuminated a p h o t o c a t h o d e , w i t h i n 427-193 nm. Four d i f f e r e n t v a r i a n t s o f t h e PIMES method have been employed in the measurements. These were acceptor, kinetic, recombination and a m e t h o d b a s e d on t h e m e a s u r e m e n t of phatocurrents in dilute electrolyte solutions. In the energy range under~ discussion, the t h e r m a l i z a t l o n l e n g t h s o f e l e c t r o n s v a r i e d f r o m 5 t o 120 A i n w a t e r , and from 5 t o 40 o a i n m e t h a n o l . The dependence o f t h e r m a l i z a t l o n l e n g t h on energy is i n t e r p r e t e d in terms o f the t h e o r y o f n o n - l o c a l losses, taking into account the elastic scattering o f electrons during thermalization. This method has also been used to study the lifetimes of aromatic radlcal-anions of halobenzoic acid. The t i m e s ranged from 10 4 to 109s. Having s t u d i e d a few tens of objects we c o n c l u d e that the lifetime of r a d i c a l - a n i o n s depends on t h e n a t u r e o f t h e h a l o g e n ano i t s position in the r i n g r e l a t i v e t o a c a r b o x y l a t e group. I t i n c r e a s e s i n t h e s e r i e s F>CI>Br and m e t a > p a r a > o r t h o ( C l , B r ) and m e t a < p a r a < o r t h o ( F ) . The PIMES method has been compared t o t h e c o n v e n t i o n a l method o f p u l s e d r a d i o l y s l s .
Symposium Abstracts
CHENIS~TRY
RADIATION
72.
PNOTOINDUCED
CHARGE ~EPARATION OF MICELLES AND
ACROSS ~RFACTANT VESECLES~
INTERFACES
LARRY KEVAN Department
of Chemlstry~ Univereity Houston, Texas 77204-5641
of
Houston
The s t r u c t u r a l aepects controlling photoinduced charge s e p a r a t i o n of solutes i n m i c e l l e s and v e s i c l e s a r e b e i n g s t u d i e d t o o p t i m i z e t h e storage of light energy. E l e c t r o n s p i n r e s o n a n c e (ESR) i s used to detect the paramagnetic p h o t o l n d u c e d c a t i o n s and t o p r o b e t h e i r s u r r o u n d i n g s . I n t e r a c t i o n s between t h e p h o t o i n d u c e d c a t i o n and w a t e r as w e l l as o t h e r s t r u c t u r a l information can be studied by electron spin echo modulation ( E S E M ) which enables the determination of weaker e l e c t r o n - n u c l e a r hyperflne interactions than one n o r m a l l y d e t e c t s by ESR. Photolonizatlon of a solute in m i c e l l e s or vesicles requires electron transfer to or through the interface region. How modifications of this interface r e g i o n p r o v i d e s a p o t e n t i a l c o n t r o l mechanism f o r t h e p h o t o i o n i z a t i o n process w i l l be d i s c u s s e d i n c u r r e n t w o r k , l o c a t i o n c o n t r o l of electron donors and acceptors with respect to a micelle or vesicle interface are being i n v e s t i g a t e d by a d d i n g a l k y l c h a i n s o f variable length to such molecules. Alkylmethylviologens are proving effective for this purpose. ESEM e n a b l e s assessment of the Location relative to the mlcelle or vesicle interface.
73.
STUDY OF THEPJ~ALIZATION ANIONS IN POLAR LIQUIDS A.M.
Institute
RAITSIMRING, of
LENGTHS AND LIFETINES O F RI~)ICAL BY PNOTOINJECTION METHODS'"
A.I.
KALUGIN,
Chemical K i n e t i c s
V.V.
KONOVALOV
and C o m b u s t i o n , N o v o s i b i r s k
The method o f e l e c t r o n p h o t o i n j e c t l o n f r o m a m e t a l t o an e l e c t r o l y t e solution (PIMES) has been used t o s t u d y t h e dependences o f thermalizatlon lengths of s l o w e l e c t r o n s on t h e i r e n e r g i e s i n w a t e r and m e t h a n o l . The r a n g e o f maximum e n e r g i e s w i t h i n w h i c h t h e measurements w e r e u n d e r t a k e n was 0 . 2 - 5 eV and the r a n g e o f mean e n e r g i e s , 0 . 1 - 3 eV. The e n e r g y o f i n j e c t e d e l e c t r o n s was changed by v a r y i n g b o t h t h e p o t e n t i a l and t h e l i g h t wave l e n g t h which illuminated a p h o t o c a t h o d e , w i t h i n 427-193 nm. Four d i f f e r e n t v a r i a n t s o f t h e PIMES method have been employed in the measurements. These were acceptor, kinetic, recombination and a m e t h o d b a s e d on t h e m e a s u r e m e n t of phatocurrents in dilute electrolyte solutions. In the energy range under~ discussion, the t h e r m a l i z a t l o n l e n g t h s o f e l e c t r o n s v a r i e d f r o m 5 t o 120 A i n w a t e r , and from 5 t o 40 o a i n m e t h a n o l . The dependence o f t h e r m a l i z a t l o n l e n g t h on energy is i n t e r p r e t e d in terms o f the t h e o r y o f n o n - l o c a l losses, taking into account the elastic scattering o f electrons during thermalization. This method has also been used to study the lifetimes of aromatic radlcal-anions of halobenzoic acid. The t i m e s ranged from 10 4 to 109s. Having s t u d i e d a few tens of objects we c o n c l u d e that the lifetime of r a d i c a l - a n i o n s depends on t h e n a t u r e o f t h e h a l o g e n ano i t s position in the r i n g r e l a t i v e t o a c a r b o x y l a t e group. I t i n c r e a s e s i n t h e s e r i e s F>CI>Br and m e t a > p a r a > o r t h o ( C l , B r ) and m e t a < p a r a < o r t h o ( F ) . The PIMES method has been compared t o t h e c o n v e n t i o n a l method o f p u l s e d r a d i o l y s l s .