Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.elch.chem.msu.ru/rus/fnm/fnm12_f.pdf Äàòà èçìåíåíèÿ: Mon Oct 29 22:37:19 2012 Äàòà èíäåêñèðîâàíèÿ: Sun Feb 3 00:55:59 2013 Êîäèðîâêà:

:

, ,
( «» «»)
: feldman@rc.chem.msu.ru


C..

( )


:
· W. Weyl (1864): ( ?) · C.A. Seely (1871): ( !) ??? · C.A. Kraus (1908): « » ­ (> 8%) ­ ( - Li : = 1.5 . 106 /) ­ « » (?) - , « » (??)

?
(. « » .: , 1979)


...
· · · · · : "digger" or "seeker" ? · · e-aq · · · ( )


Why do we care about solvated electron ?
· Basic understanding of electron transport and localization in condensed media, related to molecular electronics, chemical physics and biophysics · One of the key species in radiation chemistry, photochemistry and photoelectrochemistry in solutions · Preparative chemistry and environment-friendly technologies: unique chemical reagent (clean and very efficient reducing agent) · Unique probe for microscopic properties of disordered media (including confined environment, organized assemblies and interfaces) ­ electric, optical and magnetic response



· (excess) ­ , ( , .) · «» (e-qf), : E = V0 (V0 ­ ­ )

V0 · 1) : V0 = liq- vac
· 2) : V0 = Ig ­ Iliq ­ P+ P+ = (e2/80r )(1 ­ -1)


V0
- - V0, 1.0 0.6 ~0.2 ~0 ~0 u, c2 /(. )* 0.02 0.002 0.014 0.15 0.09




~0
- 0.14 - 0.43 - 0.6 - 0.65 - 0.65 - 1.3 (?)

400
0.1 70 100 2200 0.0003 0.002

*u = v/E, EA = 0.02 ­ 0.5 ( EA< 0)


.
· ­ ­ . ( « », ) «» : m* > m (m ­ , m me) : .. , .. ; H. FrÆlich C ( <<1 ­ , - ):

· · ·

2e 2 m1/ 2 1 1/ 2 3 / 2 ( 1 ) 2l
· ( 5): (rl ­ ~ 1 ) )

m* 0.023 m

4

· ·

«», , , , ...



· P.W. Anderson (1958; , 1977): , () · , ,



U

(« »
: g ­ ( g < F)

· (t ), (R) ~ const R<>L
· () : = 0 T = 0 K; «» T > 0


( )
· «» () M (s) + e-qf M-.(s) · O2 (s) + e-qf O2-.(s) (1) · CO2 (s) + e-qf CO2-.(s) (2) · CH3COCH3 (s) + e-qf CH3COCH3 -.(s) (3) · : (EAg 0, 3), . . |Gs(M)|<< |Gs(M-.)| · : Mn (s) + e-qf Mn -.(s)

· -


:
· (, ) ( ) · ·




(1962): 1 ­
, 2 ­ , 3 ­ , 4 ­ , 5 ­ , 6 ­ , 7 ­ , 8 ­ )

(.) = 2 , 5 ; 300 ­ 880
(pulse-probe) :

(.) = 10 , 1 (Orsay, France, 2006) (.) = 100 , 250 (Osaka, Japan, 2009)



· J.W. Boag, E.J. Hart (1962): (max ~ 720 ) (e-aq) [ ~ 20 ] H2O --/\/\- H2O +., H2O *, e H2O +.+ H2O H3O+ + OH. e- e-aq H2O * H. + OH. (?)
-

: (1) : (., .OH, H2O2, H3O+, OH-) (2) ( : O2, O2,N2O)
J.W. Boag, E.J. Hart, Nature, 1963, 197, 45; J.P. Keene, Nature, 1963, 197, 47


e
· : z = -1, S = ½ ( ­ -) · (298 ): max = 715 (Emax = 1.73 ) max = 1.85 . 104 M -1-1 1/2 = 0.93 F 0.7 ( )* · (283 , ) g = 2.00043 ( ge) B < 0.01 mT ( ?)
*)F ­ , ; F = 4.315 * 10-9 d ( = 1/)
e
-

-

aq

e

-

aq

298 ()

(Jeevarandan & Fessenden J. Phys. Chem., 1989, 93, 3511) ­ in situ

aq

296


: e-s

max

,

Emax , 1.96 1.77

, D 1.67 1.70

33.6 25.1

630 700




820
580 ~2100

1.5
2.1 ~0.6

1.65
2.28 1.63

19
38 7.3

-
(225 )

> 1600
1400 715

< 0.8
0.89 1.73

0.08
1.44 1.83

1.89
22 80

Emax ­ ( e-s) Emax (. ) ()


,
1. , : CH3COCH3 + e- CH3COCH3 -. RX + e- R. + X- (X = Cl, Br, I,...) ( - ) 2. , ( ) : CH4, (CH3)4C, (CH3)4Si ( , «» )


() 77
­ , «», ­ «» ( / ~ 1015 ­ 1030) e-tr (e-tr)

2-



max

,

Emax , 2.38 2.28 1.92 2.41 1,0

B, ()
~1.4 ~1.2 ~1.0 ~1.5 0.4

520 540 645 500 1250

3-
()*

1650
630

0.75
1.96

0.3
~1.5

e-s e-tr . Emax (e-tr) > Emax (e-s) (E ~ 0.2­0.4 ). B Emax ( e- )
*


:
· : · 1. ( ): , . · 2. - () · 3. Molecular dynamics simulation : - ( ) - () - ? - - () ­


( 1960)
· · · . . (1948, .. ): : V = - e2/r ( = -1- -1) : 1s 2p

Emax ( ) E E2 p E1s 1.93
· · · · ·

2

m* m

m*/m: 1.5 (); 2.7 () ( ?) (-) m* (-) Emax (T, p) (-) (-)



Jortner et al. (1964): «» R0 · : V = - e2/r (r > R0) V = - e2/ R0 (r < R0) 1s 2p . Emax R0 · R0 = 0.30 ­ 0.34 ( NH3) · ( ) R0 = 0.14 ­ 0.15 · e-aq : · dEmax/dT = - 2.9 . 10-3 / (<0, ) · dEmax/dp = 8 . 10-7 / (>0, ) · Emax () c B () ­ , . ?


- ()
· («») + : ( Xn- .)solv · : - (H2O) - ( , )
n ( ): n = 6 (), n= 4 (), n = 3 ()
-.

n


e-tr 77

2- (L. Kevan, Acc. Chem. Res., 1981, 14, 138)


Molecular dynamic simulation

The structure of hydrated electron as revealed by ab initio MD simulation for excess electron embedded in a water cluster (n = 32) at 300 K. Radial density of the excess electron averaged over the angular variables (green) and radial distribution function of water oxygen (red) and hydrogen (black) atoms relative to the center of the excess electron from equilibrium configurations at T = 300 K.

(Marasalek et al., Acc. Chem. Res., 2012)


MD simulation: preliminary conclusions
Effect of temperature:

· · ·

30 K: "cushion-like" state ? 300K: cavity A cavity model can be adopted as a rough approximation Cavity is more flexible and accessible to water molecules (as compared to those containing negative ions) The configuration of solvated electron at low temperature (in frozen ice) may be significantly different (?) (Marasalek et al., Acc. Chem. Res., 2012) ...still far from being clear


: "digger" or "seeker" ?
· Digger: «» · Seeker: «» ( ), (preexisting trap, pre-trap)

· : (J.H. Baxendale, P. Wardman, Nature, 1971, 230, 449) (, 1- 2-, = 150 ­ 180 K)
e-loc(, max>1350 ) e-s (max= 700 ­ 800 ) e-loc ­ ( «» )

· : S = 3 (166 ) · 1- S = 5 (178 ); 60 (152 ) · 2-: S = 6 (186 ) · 1- : S = 4 (184 ) 1 = 10-9


... both "digger" and "seeker" ?
e-qf e-loc e-s
seek .... dig

2- : «» ( ­ "digging") ( ) ?



300 (G.A. Kenney-Wallace, 1982)



S, 11 18

2,, * 12 20

, 0.55 1.10

1-
1- 1- 1-

24
30 45 51

22
27 39 48

2.00
2.60 8.95 14.1

*

(, )
S (e
aq

S ~2 ("digging" ?)

) = 0.54 (Yoshida et al., 2010) 1 = 10-12



· 1. - ( , . ): · M + . + e-qf (e-qf e-loc e-s) () · 2. , Fe(CN)64- , , SO32- ( = 220 ­ 500 )

· 3. ( )
· 4. ( ): · Na + NH3 Na+ + e-s · Na(Hg) + H2O Na+ + e-aq · U3+ + H2O U4+ + e-aq ...


e
· · · · · 0 = - 2.87 G0 = -157 / H0 = -136.4 / S0 = 69.8 / (. ) S0hydr = 49 / (.K)

-

aq

G0 (e-aq ) e-aq + H+aq ½ H2 (aq · ½ H2 (aq) ½ H2 (g) · ½ H2 (g) Hg · H g e -g + H + g · H+g H+aq --------------------e-aq e-g

)


e

-

aq

: 0- (e-aq) = 185 2/( . -)
(.: -: 198; Cl-: 70)

u- (e-aq) = 1, 92 .10 -3 c2 /(. ) D (e-aq) = 4.96 .10 -5 c2 /
( , «» )



·

e

-

aq

­ «» ( , , «» )


e

-

aq

· e-aq + Mn+ M(n-1)+ (k kdiff) e-aq + Ni2+ Ni+ e-aq + Ag+ Ag0 e-aq + Cu+ Cu0 e-aq + NO3- NO32e-aq + MnO4- MnO42 e-aq + O2 O2-. e-aq + CH3COCH3 CH3COCH3-. e-aq + C6H6 C6H6-. : e-aq + N2O N2 + O-. e-aq + RBr R. + Br-


e
· > 1500 e-aq ( , , , ...)

-

aq

k, M-1c-1* Cd(II) Ag (I) Cu(II) MnO O
4 -

5.1.10 3.9.10 3.5.10 3.3.10 3.10
10

10 10 10 10

: · - () · - «» · -


2

1.9.10 9.1.10 7.7.10

10 9 9

N2O CO
2




6.6.109
1.2.107( pH=11- 13) < 10
4

*pH = 7,


- e-aq:
1. -) A + B: k kdif ( )

k

d if

4rDN 1000

A

r = RA + RB; D = DA + DB ( )

k

d if



4reff DN 1000

A

( , ) k
dif

exp (U / kT ) reff dx 2 x r



~ 1010 M-1c

-1

e-aq «» e-aq ( - ) R ~ 0.25


e-aq:
· 2. : k << k e e
aq aq dif 6 -.

+ C 6H 6 C 6H

(k =1.2 .107 M-1c-1)
.

+ CH3 OH CH3 O- + H

(k < 104 M-1c-1)

, ·3. («» ): k > k
dif

e-aq + Cu2+ Cu+ (k = 3.5 .1010 M-1c-1) r > RA + RB ( 1 ­ 1.5 ) ( )


:

· , · : Cd(I), Zn(I), Hg(I), In (II), Eu (II), Yb (II), Sm (II), Am (II) · : Pb0 , Ag0 ·


e-aq
e-aq + Mn+ M(n-1)+ ....Mkr+ (r
, ( )


:
· · , - ( ) · () · , (), ,



· (: , , ) · - («-») : ( OH) + (e-aq ) () e-aq + RCl R. + ClR. + R . R-R ( ) e
aq

+M

n+

M(n

-1)+

....Mkr+ (r





e-aq c D2O p (Jay-Gerin et al., JCP, 2008,129,141511)

e-aq R4NNTf2 (Wishart & Neta, JPC B, 2003, 107, 7261)


:
· (, ) · ( , ) · · «» «» · «» ·