213
COMMUNICATIONS TO THE EDITOR Similar measurements were made a t lower pH's (Table I). Acidity was adjusted with H2S04, except a t
+
GH Calculated from G(H202) in Solutions Table I : G,,,of O2 + Hz and from G(Fe"1) in Air-Free Solutions of FeSOd, Both Irradiated with Con0 y Rays. The pH's Were Adjusted with HzS04 and Also with HClOl a t p H 0.46
a
G(HnOd
6.50 4.25 2.74 2.05 1.51 1.00 0.46" 0.46
3.66 3.66 3.69
3.21 3.21 3.25
3.88
3.46
4.07
3.67
From eq a.
Geaq-
+G H ~
PH
' From eq b.
G(FeT1I)
Gess- f GH*
7.40 7.55 7.77 7.96 8.14 8.14
3.26 3.34 3.47 3.57 3.67 3.67
HClO,.
pH 0.46. At this pH, HC1O4 was used in order to avoid complications from the reaction of OH with H2S04 (IC = 4 X lo6 M-' sec-1).6 The values of G,,,GH in the third column were calculated from has eq a, using reported values for GH~." Since not been measured in pH 0.46 HC104, we used the same value 0.40 as in p H 0.46 H2S04.'3 For comparison, G(FelI1) was measured in y-irradiGH calculated ated air-free 5 mM FeS04 and Ge,,froml9
+
+
+
The two sets of values for Get,GH agree to within 0.3%- The G(FelI1)'s are the same in pH 0.46 HClOl and H2S04.
C O M M U N I C A T I O N S TO T H E E D I T O R
Electronic Absorption Spectra of Cyclohexadienyl Radical in y-Irradiated Solids at 77°1
