PHOTOELECTRON INJECTION INTO AQUEOUS AND METHANOLIC SOLUTIONS SATURATED WITH SF6

The method of pulse laser photoelectron injection from metal into elec trolyte solutions (PIMES) has been used to study the bulk and electrod e reactions of intermediates (SF5 and SF4) obtained by reduction of SF 6 by solvated electron in aqueous and methanolic solutions. The experi mental data for both solvents were explained in the framework of the g eneral reaction mechanism. The total electron-transfer number v(0) of the photoelectrochemical process was found to depend on both the elect rode potential phi and the delay time, increasing from 2 to 6. The SF5 . radical undergoes one-electron reduction to SF4, which subsequently undergoes four-electron reduction to S. The rate constants of the homo geneous decay of the radical anion SF6-(greater than or equal to 10(10 ) s(-1)) and the reactions of the SF5. radical with water (3X10(4) M(- 1) s(-1)) and methanol (less than or equal to 2x10(4) M(-1) s(-1)) hav e been estimated. The time-resolved photopolarograms allow the followi ng stages in the electrode reactions of fast transients to be distingu ished: SF5.+e(m)(-)-->SF4+F- (occurring at delay times t<100 ns for ph i less than or equal to-0.2 V/SCE/); SF4+2e(m)(-)-->SF2+2F(-)(t less t han or equal to 100-200 ns, half-wave potential phi(1/2) is -0.6 V for water and -1.2 V for methanol); SF2+2e(m)(-)-->S+2F(-) (at times up t o 10 mu s depending on the electrode potential).